JP6527558B2 - Printing system, method of generating halftone processing rule, image processing apparatus and program - Google Patents

Description

  The present invention relates to a printing system, a method of generating halftone processing rules, an image processing apparatus, and a program, and more particularly to an image processing technique for generating a halftone image for printing from a continuous tone image.

  In a printing system in which an image is formed by a printing apparatus such as an inkjet printing apparatus or an offset printing apparatus, a halftone process is performed on data of a continuous tone image represented by multiple gradations, thereby achieving an image output method of the printing apparatus. Corresponding halftone image data is generated. Data of a halftone image is used as dot image data for printing showing a dot arrangement of halftone dots reproduced by a printing apparatus and a dot pattern in which the size of each dot is defined. The printing apparatus forms an image based on the halftone image data.

  There are various halftoning methods such as dithering, error diffusion, and direct binary search (DBS). For example, the dither method uses a threshold matrix called a dither mask, compares the magnitude relationship between the pixel value of the processing target pixel and the threshold, assigns dot on when the pixel value is equal to or greater than the threshold, and In the case of less than the threshold value, the multi-value continuous tone image data is converted into binary dot data by assigning the dot off.

  Patent Document 1 proposes a printing system capable of selecting halftone processing suitable for printed matter in consideration of production suitability of the printed matter. The printing system described in Patent Document 1 selects one signal processing condition from a plurality of signal processing conditions of halftone processing having different dot distribution characteristics, and executes halftone processing using the signal processing condition related to the selection. be able to.

JP 2012-222433 A

  Printing results based on halftone images generated by halftoning depend on the characteristics of the printing system. Therefore, it is desirable to generate halftone processing rules suitable for the printing system based on the characteristic parameters relating to the characteristics of the printing system.

  As characteristic parameters relating to the characteristics of the printing system, for example, in the case of an inkjet printing system, resolution, number of nozzles, ink type, average dot density, average dot diameter, average dot shape, dot density of each printing element, dot diameter, dot shape, There are dot formation position deviation, non-ejection, landing interference and the like. Among the various characteristic parameters exemplified here, the dot density, dot diameter, dot shape and landing interference parameters of each printing element vary depending on the combination of the ink, printing medium, and recording head characteristics to be used, and Since the dot formation position deviation and the non-ejection also change depending on the state of the recording head, inputting appropriate values by the user for these various parameters requires a large workload. Note that the characteristics of the recording head include the waveform and frequency of a drive signal applied to the recording head when discharging ink, and the state of the recording head is, for example, the inclination or bending of the recording head, Indicates the distance and the state of each printing element.

  The present invention has been made in view of such circumstances, and enables setting of characteristic parameters relating to the characteristics of the printing system without imposing much load on the user, and obtaining halftone processing rules suitable for the printing system. Printing system, a method of generating halftone processing rules, an image processing apparatus, and a program.

  The following invention aspects are provided in order to achieve the said objective.

  The printing system according to the first aspect outputs a characteristic parameter acquisition chart output unit that outputs a characteristic parameter acquisition chart that includes a pattern for acquiring a characteristic parameter related to the characteristic of the printing system, and a characteristic parameter acquisition chart output unit Image reading means for reading the acquired characteristic parameter acquisition chart, characteristic parameter acquisition means for acquiring a characteristic parameter by analyzing a read image of the characteristic parameter acquisition chart obtained by the image reading means, and characteristic parameter acquisition means And a halftone processing generation unit configured to generate a halftone processing rule that defines processing content of halftone processing to be used in the printing system based on the characteristic parameter acquired via the processing unit.

  According to the first aspect, the characteristic parameter acquisition chart is output by the printing system, and the output characteristic parameter acquisition chart is read by the image reading unit. Information of the characteristic parameter is acquired from the read image of the characteristic parameter acquisition chart, and a halftone processing rule suitable for the printing system is generated based on the acquired characteristic parameter.

  According to the first aspect, it is possible to easily set the characteristic parameters of the printing system without imposing much load on the user, and it is possible to generate halftone processing rules suitable for the characteristics of the printing system.

  As a second aspect, in the printing system of the first aspect, the halftone processing rule may be configured as specified by a combination of a halftone algorithm and a halftone parameter.

  As a third aspect, in the printing system of the second aspect, any one of a dither method, an error diffusion method, or a direct binary search method can be adopted as a halftone algorithm.

  According to a fourth aspect, in the printing system of the second aspect or the third aspect, the halftone parameter includes the size of the dither mask in the dither method, and the threshold, the size of the error diffusion matrix in the error diffusion method, the diffusion coefficient, and each error The configuration may include at least one parameter of the setting of the application gradation section of the diffusion matrix, the number of pixel updates in the direct binary search method, the exchange pixel range, and the evaluation parameter of system error tolerance.

  According to a fifth aspect, in the printing system according to any one of the first to fourth aspects, the printing system includes an image forming unit having a plurality of printing elements responsible for forming dots on the printing medium. The characteristic may be a characteristic including at least one of individual recording characteristics of the plurality of printing elements and characteristics common to the plurality of printing elements.

  As a sixth aspect, in the printing system according to the fifth aspect, the recording characteristic is a characteristic including at least one of dot density, dot diameter, dot shape, dot recording position error, and unrecordable abnormality. be able to.

  As a seventh aspect, in the printing system according to the fifth aspect or the sixth aspect, the common characteristic is a characteristic including at least one of average dot density, average dot diameter, average dot shape, and landing interference. It can be configured.

  As an eighth aspect, in the printing system according to any one of the fifth aspect to the seventh aspect, the characteristic parameter acquiring unit carries out the recording plural times using the same printing element by the characteristic parameter acquiring chart output unit. Parameters relating to individual recording characteristics of the printing element and characteristics common to a plurality of printing elements can be acquired from the read image of the characteristic parameter acquisition chart.

  As a ninth aspect, in the printing system according to any one of the fifth aspect to the eighth aspect, the characteristic parameter acquiring unit executes the recording plural times using the same printing element by the characteristic parameter acquiring chart output unit. The parameter related to the error of the printing system can be acquired from the read image of the characteristic parameter acquisition chart.

  As a tenth aspect, in the printing system according to any one of the fifth to ninth aspects, the chart for characteristic parameter acquisition includes a pattern of continuous dots recorded by bringing two or more dots into contact, and the characteristic parameter The acquisition means can be configured to acquire parameters relating to landing interference from the pattern of continuous dots.

  As an eleventh aspect, in the printing system according to the tenth aspect, the characteristic parameter acquisition chart includes a plurality of dots having an inter-dot distance between two or more dots and / or a difference in recording time between two or more dots. It may be configured to include a pattern of continuous dots of a kind.

  As a twelfth aspect, in the printing system according to any one of the fifth aspect to the eleventh aspect, the characteristic parameter acquisition chart is a discrete in which a single dot is discretely recorded in an isolated state separated from other dots. The characteristic parameter acquisition means may be configured to generate dispersion information on dot dispersion from the pattern of discrete dots, including a dot pattern.

  As a thirteenth aspect, in the printing system according to any one of the first aspect to the twelfth aspect, the halftone processing generation means balances the priorities for a plurality of request items required for halftone processing based on the characteristic parameter. Can be configured to generate halftone processing rules of two or more types of halftone processing different from each other.

  In a fourteenth aspect, in the printing system according to the thirteenth aspect, the plurality of requirements include at least two of image quality, cost, halftone generation time, halftone processing time, tolerance to system errors, and tolerance to environmental fluctuations. It can be configured to include items.

  According to a fifteenth aspect, in the printing system according to the thirteenth aspect or the fourteenth aspect, two or more types of halftone processing rules generated by the halftone processing generation means are registered as candidates for halftone processing usable in the printing system. A halftone registration unit may be provided.

  According to a sixteenth aspect, in the printing system according to any one of the thirteenth to fifteenth aspects, using two or more types of halftone processing rules generated by the halftone processing generation means, the quality of each halftone processing A halftone selection chart output unit that outputs a halftone selection chart including a comparative evaluation image area can be provided.

  According to a seventeenth aspect, in the printing system according to any one of the thirteenth to sixteenth aspects, the image quality, cost, halftoning time, and halftoning time of the halftoning defined by the halftoning rule. It can be set as composition provided with an evaluation value calculation means which computes an evaluation value which carries out quantitative evaluation of at least one item among them.

  As an eighteenth aspect, the printing system according to the seventeenth aspect can be configured to include an information presenting unit that presents information of the evaluation value to the user.

  According to a nineteenth aspect, in the printing system according to any one of the thirteenth to eighteenth aspects, among the types of halftone processing defined by two or more types of halftone processing rules generated by the halftone processing generation means The present invention can be configured to include halftone selection operation means for performing an operation of the user selecting the type of halftone processing used for printing.

  According to a twentieth aspect, in the printing system according to any one of the thirteenth to nineteenth aspects, among the types of halftone processing defined by two or more types of halftone processing rules generated by the halftone processing generation means From the above, it is possible to provide halftone automatic selection means for automatically selecting the type of halftone processing to be used for printing of the printing system based on the priority parameter regarding the priority for a plurality of requirement items.

  According to a twenty-first aspect, the printing system according to the twentieth aspect can be configured to include a priority input unit for the user to input information related to the priorities of the plurality of request items.

  In a twenty-second aspect, in the printing system according to the twentieth aspect or the twenty-first aspect, the automatic halftone selection means evaluates the appropriateness of the halftone processing defined by the halftone processing rule generated by the halftone processing generation means. It includes a judgment evaluation value calculation unit that calculates a judgment evaluation value based on a priority parameter, and automatically determines the type of halftone processing used for printing in the printing system based on the judgment evaluation value calculated by the judgment evaluation value calculation unit. It can be configured to be selected.

  According to a twenty-third aspect, in the printing system according to any one of the twentieth aspect to the twenty-second aspect, the halftone automatic selection unit includes halftone processing defined by the halftone processing rule generated by the halftone processing generation unit. A simulation image generation unit that generates a simulation image when printing a halftone image obtained by application and an image quality evaluation value calculation unit that calculates an image quality evaluation value from the simulation image can be provided.

  According to a twenty-fourth aspect, in the printing system according to any one of the twentieth aspect to the twenty-third aspect, the priority parameter holding means for holding the priority parameter can be provided.

  According to a twenty-fifth aspect, in the printing system according to any one of the first to twenty-fourth aspects, setting means for setting a parameter regarding a system error assumed when printing is performed by the printing system, and a system indicated by the parameters A means for generating a simulation image reflecting an error, and an image quality evaluation means for evaluating the image quality of a simulation image reflecting a system error, the parameters include characteristic parameters, and the halftone processing generation means evaluates Halftone processing rules can be generated based on a simulation image that falls within the target range.

  The “means for generating a simulation image” may be the same processing means as the “simulation image generating means” in the twenty-third aspect, or may be provided with separate processing means.

  The “simulation image reflecting the system error” means a simulation image generated under the condition to which the system error is added in the condition setting of the simulation when generating the simulation image.

  The “target range” is a predetermined range defined as a target of image quality. The range of targets can be defined as an image quality target that can meet the required image quality. The target range can be defined as a condition for ensuring that the image quality is good at an acceptable level. In addition, the range of the target can include that the evaluation value as an index for evaluating the image quality is the best.

  According to the twenty-fifth aspect, it is possible to generate halftone processing rules suitable for the printing system in consideration of a system error that assumes actual printing by the printing system. As a result, it is possible to realize appropriate halftone processing that can obtain good image quality, and to obtain a print image of good image quality.

  According to a twenty-sixth aspect, in the printing system according to the twenty-fifth aspect, the system error includes a characteristic error expected to be repeatable as a characteristic of the printing system, and a random system error as an irregularly changing error. Can.

  The expression "reproducibility is expected" includes reproducible ones and the possibility of reasonably high probability of reproducibility from statistical probability distribution. For example, the average value or the median value of the distribution of the measurement values of the system error can be used as the “characteristic error”.

  "Irregularly changing" includes changing with time or depending on location. The error that changes irregularly is an error that is less reproducible than the characteristic error, and can be grasped from the statistical probability distribution as a component of “dispersion” for the characteristic error. Random system error is understood to be a fluctuation component added to the characteristic error. The random system error as a fluctuation component added to the characteristic error may have both positive and negative values.

  According to a twenty-seventh aspect, in the printing system according to the twenty-sixth aspect, a plurality of levels are defined regarding the value of the random system error, and each level reflecting random system errors corresponding to each of the plurality of levels by the means for generating a simulation image. The simulation image of may be generated.

  As a twenty-eighth aspect, in the printing system according to the twenty-seventh aspect, the plurality of levels can be configured to be determined according to the system error distribution of the printing system.

  According to a twenty-ninth aspect, in the printing system according to the twenty-eighth aspect, the image quality evaluation unit evaluates the image quality of each of the simulation images for each level, and calculates an image quality evaluation value integrated with the image quality evaluation of the simulation image for each level. It can be done.

  As a thirtieth aspect, in the printing system according to any one of the twenty-seventh aspect to the twenty-ninth aspect, the image quality evaluation means is a sum of evaluation values of simulation images for each level or weighting coefficients for evaluation values of simulation images for each level. The weighting factor may be determined according to a system error distribution of the printing system.

  According to a thirty-first aspect, in the printing system according to any one of the twenty-fifth to thirty-third aspects, a storage unit for storing data of parameters acquired in the past is provided, and halftone processing is performed based on the stored data. The rules can be configured to be generated.

  According to a thirty-second aspect, in the printing system according to the thirty-first aspect, the system error distribution information of the printing system may be updated based on the stored data.

  As a thirty-third aspect, in the printing system according to the thirty-first aspect or the thirty-second aspect, characteristic parameter update determining means for determining whether to update the characteristic parameter, and whether to update the characteristic parameter in the characteristic parameter update determining means The characteristic parameter update determination means is acquired in the past stored in the storage unit and the new characteristic parameter acquired by the characteristic parameter acquisition means. The configuration may be such that the characteristic parameter is updated when the difference from the existing characteristic parameter exceeds the predetermined value acquired by the predetermined value acquiring unit.

  According to a thirty-fourth aspect, in the printing system according to the thirty-third aspect, the characteristic parameter update determining means determines whether to update the characteristic error expected to be reproducible as the characteristic of the printing system as the characteristic parameter. it can.

  As a thirty-fifth aspect, in the printing system according to the thirty-third aspect or the thirty-fourth aspect, the characteristic parameter update determining means determines an average dot density of the plurality of printing elements, an average dot diameter of the plurality of printing elements, a plurality of printing elements as the characteristic parameter. Average dot shape, landing interference in a plurality of printing elements, dot density for each printing element, dot diameter for each printing element, dot shape for each printing element, printing position error for dots per printing element, printing failure abnormality for each printing element , Positional deviation of dots for each droplet type, bidirectional printing positional deviation, bidirectional printing position deviation for each droplet type, head vibration error, print medium transport error, and head module vibration in a head constituted by a plurality of head modules It may be configured to determine whether to update at least one of the errors.

  As a thirty-sixth aspect, in the printing system according to any one of the thirty-third aspect to the thirty-fifth aspect, the prescribed value acquiring unit can be configured to acquire the prescribed value determined based on the stored characteristic parameter.

  As a thirty-seventh aspect, in the printing system according to any one of the thirty-third aspect to the thirty-fifth aspect, the specified value acquiring unit is configured to acquire the specified value determined based on the irregularly changing error as the characteristic of the printing system. It can be done.

  As a thirty-eighth aspect, in the printing system according to any one of the first to thirty-seventh aspects, the characteristic parameter acquisition chart output unit outputs the characteristic parameter acquisition chart in association with the continuously output image. The characteristic parameter acquisition means may be configured to acquire the characteristic parameter by analyzing the read image of the characteristic parameter acquisition chart that has already been output along with the image.

  According to a thirty-ninth aspect, in the printing system according to any one of the first to thirty-eighth aspects, the printing system further includes halftone processing means for performing halftone processing using the halftone processing rule generated by the halftone processing generation means, The characteristic parameter acquisition chart output unit appends and outputs the characteristic parameter acquisition chart for each of a plurality of images, and the halftone processing generation unit outputs the characteristic parameter acquisition chart output by the characteristic parameter acquisition chart output unit The halftone processing rule is generated based on the read image, and the halftone processing unit is configured to perform halftone processing on a plurality of images using the halftone processing rule generated by the halftone processing generation unit. Can.

  As a fortieth aspect, in the printing system according to the thirty-eighth aspect, the characteristic parameter acquisition chart output unit outputs the characteristic parameter acquisition chart in association with an image two or more images before the image to be halftoned. The characteristic parameter acquiring unit acquires characteristic parameters using the characteristic parameter acquiring chart attached to the image two or more images before the image to be halftoned processed, and the halftone processing generating unit is halftoned. The halftone processing rule can be generated using the characteristic parameter acquisition chart attached to the image two or more images before the image.

  As a forty-first aspect, in the printing system according to the forty aspect, the process of outputting the characteristic parameter acquisition chart by the characteristic parameter acquisition chart output unit, the process of acquiring the characteristic parameter by the characteristic parameter acquisition unit, and halftone processing generation Halftone processing and parallel processing by the halftone processing unit that performs halftone processing using the halftone processing rule generated by the halftone processing generation unit among any one processing of halftone processing rule generation processing by the unit Can be configured.

  As a forty-second aspect, in the printing system according to any one of the first to forty-first aspects, the printing system according to any one of the first to the 41st aspect comprises quality request acquisition means for acquiring a quality request for a print image. It is possible to change at least one of the contents of the characteristic parameter acquisition chart and the output conditions of the characteristic parameter acquisition chart according to the quality requirement for the print image acquired by the above.

  As a forty-third aspect, in the printing system according to any one of the first to forty-first aspects, the printing system further includes a quality request acquiring unit that acquires a quality request for a print image, and the image reading unit is acquired by the quality request acquiring unit. The reading conditions of the chart for characteristic parameter acquisition can be changed according to the quality requirement for the print image.

  As a forty-fourth aspect, in the printing system according to any one of the first to forty-first aspects, the printing system according to any one of the first to the 41st aspect comprises quality request acquisition means for acquiring a quality request for a print image. The method of acquiring the characteristic parameter can be changed in accordance with the quality requirement for the print image.

  As a forty-fifth aspect, the printing system according to any one of the first to forty-first aspects includes a quality request acquisition unit that acquires a quality request for a print image, and the halftone processing generation unit acquires the quality request acquisition unit by the quality request acquisition unit The content of the halftone processing rule can be changed according to the quality requirement for the printed image.

  As a forty-sixth aspect, in the printing system according to any one of the first aspect to the forty aspect, a chart output unit for dot reproduction accuracy investigation dedicated to output a dedicated chart for examining dot reproduction accuracy, and dot reproduction accuracy investigation dedicated A dot reproduction accuracy analysis means for analyzing a dedicated chart for checking the reproduction accuracy of dots output by the chart output means, and the chart output means for characteristic parameter acquisition acquires the analysis result by the dot reproduction accuracy analysis means Thus, at least one of the content of the characteristic parameter acquisition chart and the output condition of the characteristic parameter acquisition chart can be changed.

  As a forty-seventh aspect, in the printing system according to any one of the first to forty-fifth aspects, a chart output means for dot reproduction accuracy investigation dedicated to output an exclusive chart for examining dot reproduction accuracy, and dot reproduction accuracy investigation dedicated And a dot reproduction accuracy analysis unit for analyzing a dedicated chart for checking the reproduction accuracy of dots output by the chart output unit, and the image reading unit is for acquiring characteristic parameters according to the analysis result by the dot reproduction accuracy analysis unit. The chart reading condition can be changed.

  As a forty-eighth aspect, in the printing system according to any one of the first to forty-fifth aspects, a chart output means for dot reproduction accuracy investigation dedicated to output an exclusive chart for examining dot reproduction accuracy, and dot reproduction accuracy investigation dedicated A dot reproduction accuracy analysis unit for analyzing a dedicated chart for checking the reproduction accuracy of dots output by the chart output unit; and the characteristic parameter acquisition unit is configured to calculate characteristic parameters according to the analysis result by the dot reproduction accuracy analysis unit. The acquisition method can be changed.

  As a forty-ninth aspect, in the printing system according to any one of the first aspect to the forty aspect, a chart output means for dot reproduction accuracy investigation dedicated to output a dedicated chart for examining dot reproduction accuracy, and dot reproduction accuracy investigation dedicated And a halftone processing generation unit that performs halftone processing according to the analysis result by the dot reproduction accuracy analysis unit. The dot reproduction accuracy analysis unit analyzes the dedicated chart for examining the reproduction accuracy of the dot output by the chart output unit. The content of the processing rule can be changed.

  According to a fifty-fifth aspect, in the printing system according to any one of the first to the 49th aspects, characteristic parameter storage means for storing characteristic parameters related to system specifications among characteristic parameters, and a characteristic parameter acquisition chart for generating characteristic parameters The characteristic parameter acquisition chart generation unit acquires characteristic parameter acquisition based on the characteristic parameter related to the system specification acquired from among the characteristic parameters related to the system specification stored in the characteristic parameter storage unit. The chart for generating characteristic parameters is generated, and the chart output unit for characteristic parameter acquisition outputs the chart for characteristic parameter acquisition generated by the chart for characteristic parameter acquisition, and the image reading unit is output by the chart output unit for characteristic parameter acquisition Read the sex parameter acquisition chart, the characteristic parameter acquisition unit, by analyzing the read image of the obtained characteristic parameter acquisition chart by the image reading means may be configured to acquire characteristic parameters.

  According to a fifty-first aspect, in the printing system according to any one of the first to the 49th aspects, characteristic parameter storage means for storing characteristic parameters relating to system specifications among characteristic parameters, and a characteristic parameter acquisition chart are stored. A characteristic parameter acquisition chart storage unit; and a characteristic parameter acquisition chart selection unit for selecting a characteristic parameter acquisition chart from among the characteristic parameter acquisition charts stored in the characteristic parameter acquisition chart storage unit; The chart acquisition means for parameter acquisition selects the chart for characteristic parameter acquisition based on the characteristic parameters for the system specification acquired from the characteristic parameters for the system specification stored in the characteristic parameter storage means, and the chart for characteristic parameter acquisition is output. The means outputs the characteristic parameter acquisition chart selected by the characteristic parameter acquisition chart selection means, and the image reading means reads the characteristic parameter acquisition chart output by the characteristic parameter acquisition chart output means, and the characteristic parameter acquisition means According to the aspect of the invention, the characteristic parameter can be acquired by analyzing the read image of the characteristic parameter acquisition chart obtained by the image reading unit.

  According to a fifty-second aspect of the present invention, there is provided a method of generating a halftone processing rule comprising: a chart for characteristic parameter acquisition chart outputting step for outputting a chart for characteristic parameter acquisition including a pattern for acquiring a characteristic parameter relating to a characteristic of a printing system; An image reading step of reading the characteristic parameter acquisition chart output in the chart output step; and a characteristic parameter acquisition step of acquiring a characteristic parameter by analyzing a read image of the characteristic parameter acquisition chart obtained in the image reading step; A halftoning rule including a halftoning generation step of generating a halftoning rule which defines the processing content of the halftoning to be used in the printing system based on the characteristic parameter acquired through the characteristic parameter acquiring step; Is a generation method of

  In the fifty-second aspect, the same matters as the matters specified in the second to 51st aspects can be combined as appropriate. In that case, the processing unit or function unit (means) as means for carrying out the process or function specified in the printing system can be grasped as an element of the “process (step)” of the process or operation corresponding thereto.

  An image processing apparatus according to a fifty-third aspect of the present invention, based on chart data for characteristic parameter acquisition, which generates chart data of a chart for characteristic parameter acquisition including a pattern for acquiring a characteristic parameter related to a characteristic of a printing system. A characteristic parameter acquisition unit that acquires a characteristic parameter by analyzing a read image of a characteristic parameter acquisition chart printed by the printing system, and used by the printing system based on the characteristic parameter acquired through the characteristic parameter acquisition unit And an halftone processing generation unit configured to generate a halftone processing rule that defines processing content of the halftone processing.

  According to the fifty-third aspect, the chart for characteristic parameter acquisition is output by the printing system based on the chart data of the chart for characteristic parameter acquisition generated by the image processing apparatus. By reading the output characteristic parameter acquisition chart by the image reading means, a read image of the characteristic parameter acquisition chart can be obtained. The image processing apparatus analyzes the read image of the characteristic parameter acquisition chart to acquire information on the characteristic parameter, and generates a halftone processing rule based on the acquired characteristic parameter.

  According to the image processing apparatus of the fifty-third aspect, it is possible to easily set the characteristic parameters of the printing system without imposing much load on the user, and to generate halftone processing rules suitable for the characteristics of the printing system. be able to.

  In the fifty-third aspect, the same matters as the matters identified in the second to 51st aspects can be combined as appropriate.

  A program according to a fifty-fourth aspect is characterized in that the computer generates characteristic chart acquisition chart generation means for generating chart data of a characteristic parameter acquisition chart including a pattern for acquiring a characteristic parameter related to a characteristic of the printing system, and chart data. Means for acquiring the characteristic parameter by analyzing the read image of the characteristic parameter acquisition chart printed by the printing system, and based on the characteristic parameter acquired via the characteristic parameter acquisition means, the printing system It is a program that functions as a halftone processing generation unit that generates a halftone processing rule that defines the processing content of halftone processing to be used.

  With regard to the program of the fifty-fourth aspect, the same matters as the items specified in the second to 51st aspects can be combined as appropriate. In that case, the processing unit or function unit (means) as means for carrying out the process or function specified in the printing system can be understood as an element of a program for realizing the means for the process or operation corresponding thereto.

  According to the present invention, it is possible to set characteristic parameters related to the characteristics of the printing system without imposing much load on the user, and it is possible to generate halftone processing rules suitable for the printing system.

FIG. 1 is a block diagram showing an example of the configuration of a printing system according to an embodiment of the present invention. FIG. 2 is a block diagram showing an example of the hardware configuration of the image processing apparatus. FIG. 3 is a block diagram for explaining the functions of the image processing apparatus according to the first embodiment. FIG. 4 is a flowchart showing an example of a method of generating halftone processing rules. FIG. 5 is a diagram showing an example of a characteristic parameter acquisition chart. FIG. 6 is a schematic plan view of a serial scan type ink jet printing apparatus used for drawing the characteristic parameter acquisition chart of FIG. FIG. 7 is an explanatory diagram of characteristic parameters related to landing interference. FIG. 8 is a diagram showing an example of landing interference parameters expressed as a function of inter-dot distance. FIG. 9 is a chart showing the pros and cons of various halftone algorithms for a plurality of requirements. FIG. 10 is a flowchart related to halftone parameter generation processing. FIG. 11 is a conceptual view of a simulation image. FIG. 12A shows the order of droplet deposition in the drawing mode in which drawing is performed in eight scanning passes by pass numbers, and FIG. 12B shows the drawing mode in FIG. 12A. It is a conceptual diagram in the case of adding a predetermined amount of error to the dot of the pixel of the 1st pass in the case of drawing. FIG. 13 is an explanatory view in the case of giving an error in which the dot diameter is reduced by a predetermined amount with respect to the dots of the pixels belonging to the third pass in the case of drawing in the drawing mode shown in FIG. FIG. 14 is a flowchart of an example of creating a dither mask using a void and cluster method (Void-and-Cluster method). FIG. 15 is a schematic view showing an example of a halftone selection chart. FIG. 16 is a flowchart showing a procedure for generating a halftone image of a halftone selection chart by the DBS method. FIG. 17 is a graph showing the qualitative tendency of various halftone processing rules. FIG. 18 is a graph showing the relationship between the system instability and granularity. FIG. 19 is a block diagram for explaining the function of the image processing apparatus according to the second embodiment. FIG. 20 is a flowchart showing another example of the method of generating halftone processing rules. FIG. 21 is a diagram showing another example of the characteristic parameter acquisition chart. FIG. 22 is a schematic plan view of a single pass ink jet printing apparatus used for drawing the characteristic parameter acquisition chart of FIG. FIG. 23 is a schematic view showing an example of a chart for measuring the head vibration error accompanying the movement of the carriage. FIG. 24 is an explanatory view showing the amount of deviation of the recording position. FIG. 25 is a graph showing an example of head vibration error, FIG. 25 (A) shows a positional deviation amount in the main scanning direction, and FIG. 25 (B) shows a positional deviation amount in the sub scanning direction. FIG. 26 is a schematic view showing an example of a chart for measuring a sheet conveyance error. FIG. 27 is a distribution diagram showing an example of the distribution of the measurement value of the sheet conveyance error. FIG. 28 is a schematic view showing an example of a chart for acquiring a parameter of a head vibration error in the single pass method. FIG. 29 is a schematic view showing an example of a chart for acquiring a parameter of a head module attachment error. FIG. 30A is a schematic view for explaining the deviation of the position of the center of gravity of the dot row, and FIG. 30B is an explanatory view of the inclination angle of the dot row. FIG. 31 is a graph showing the relationship between the system error distribution and the level of random system error reflected in generation of a simulation image. FIG. 32 is an explanatory diagram for explaining the relationship between a plurality of levels of random system errors and weighting factors. FIG. 33 is a diagram representing the two-dimensional error distribution in the main scanning direction and the sub scanning direction by shading. FIG. 34 is an error distribution sectional view taken along the main scanning direction in the two-dimensional error distribution shown in FIG. FIG. 35 is an error distribution sectional view taken along the sub scanning direction in the two-dimensional error distribution shown in FIG. FIG. 36 is a block diagram showing the main part of the image processing apparatus according to the third embodiment. FIG. 37 is a block diagram showing the configuration of a printing system according to the fourth embodiment. FIG. 38 is a flowchart of a method of generating halftone processing rules to which characteristic parameter updating is applied according to the fourth embodiment. FIG. 39 is an explanatory diagram of an example of the update of the characteristic parameter when the system error is applied to the specified value. FIG. 40 is an explanatory view of the difference between the existing variation amount of the inter-dot distance and the variation amount of the new inter-dot distance. FIG. 41 is a flowchart of a method of generating halftone processing rules applied to a modification of the printing system according to the fourth embodiment. It is a flowchart of the production | generation method of the halftone process rule which concerns on 5th Embodiment. FIG. 43A is a conceptual diagram of a method of generating halftone processing rules according to the fifth embodiment. FIG. 43B is a conceptual diagram of a method of generating halftone processing rules according to an application example of the fifth embodiment. FIG. 44 is a flowchart of a method of generating halftone processing rules according to an application example of the fifth embodiment. FIG. 45 is a flowchart of a first modified example of the method of generating halftone processing rules according to the application example of the fifth embodiment. FIG. 46 is a flowchart of a second modification of the method of generating halftone processing rules according to the application of the fifth embodiment. FIG. 47 is a block diagram showing the configuration of an image processing apparatus applied to a printing system according to the sixth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

  FIG. 1 is a block diagram showing an example of the configuration of a printing system according to an embodiment of the present invention. The printing system 10 includes a DTP (Desk Top Publishing) apparatus 12, a database server 14, a management computer 16, an image processing apparatus 20, a print control apparatus 22, a printing apparatus 24, and an image reading apparatus 26. Equipped with The image processing apparatus 20 is connected to the DTP apparatus 12, the database server 14, the management computer 16, the print control apparatus 22, and the image reading apparatus 26 through a telecommunication line 28.

  The telecommunication line 28 may be a local area network (LAN), a wide area network (WAN), or a combination thereof. The telecommunications line 28 is not limited to a wired communication line, but can be a part or all of a wireless communication line. Further, in the present specification, the notation “connection” between devices capable of passing signals includes not only wired connection but also wireless connection.

  The DTP device 12 is a device that generates data of an original image indicating the content of an image to be printed. The DTP device 12 is realized by a combination of computer hardware and software. The term software is synonymous with program. The DTP device 12 is used to edit various types of image components such as characters, figures, patterns, illustrations, and photographic images to be printed, and to lay out on the printing surface.

  Original image data as print source image data is generated by an editing operation or the like by the DTP device 12. The DTP device 12 generates an electronic document in page description language (PDL). The document image data generated by the DTP device 12 is transferred to the database server 14 and the image processing device 20. The means for generating the document image data is not limited to the form created by the DTP device 12, but may be created by another computer (not shown) or an image creation / editing device etc. The document image data can be input to the database server 14, the image processing apparatus 20, the print control apparatus 22 or the like through the electric communication line 28 or using removable media (external storage media) such as a memory card.

  The database server 14 is a device that manages various data such as job tickets for electronic originals, color sample data, target profiles, and device profiles suitable for the combination of the printing apparatus 24 and paper. The job ticket can be, for example, in the form of a JDF (Job Definition Format) file.

  The management computer 16 performs various management in the printing system 10. For example, image management, management of print jobs, management of the operation status of one or more printing devices 24, and the like are performed.

  The image processing apparatus 20 functions as a unit that rasterizes original image data for printing (for example, data described in a page description language) generated by the DTP device 12 or the like. Rasterization processing is called RIP (Raster Image Processor) processing. The image processing device 20 can be realized as one function of the RIP device.

  The image processing apparatus 20 has a color conversion processing function and a halftone processing function for converting document image data for printing which is a continuous tone image into data of dot patterns classified by color suitable for output by the printing apparatus 24. Further, the image processing apparatus 20 of the present example has a function of generating two or more types of halftone processing rules based on the characteristic parameters of the printing apparatus 24 in the printing system 10 regarding the halftone processing function. That is, the image processing apparatus 20 has a halftone processing generation function of generating a halftone processing rule, and a halftone processing function of performing halftone processing on a continuous tone image using the generated halftone processing rule. There is. The image processing apparatus 20 can be realized by a combination of computer hardware and software.

  The halftone processing rule is a processing rule for performing halftone processing for converting data of a continuous tone image into data of a halftone image which is data of a dot pattern. Halftoning rules are defined by the combination of the halftoning algorithm and the halftoning parameters. The halftone processing rule means a specific operation scheme of halftone processing, and specifies the content of halftone processing.

  As a type of halftone algorithm, for example, there are a dither method, an error diffusion method, a direct binary search method, and the like. The halftone parameter is a specific parameter used for arithmetic processing in accordance with the halftone algorithm. Halftone parameters are determined for each halftone algorithm. For example, the size and threshold of the dither matrix are determined as halftone parameters in the case of dithering. As a halftone parameter in the error diffusion method, there are a matrix size of an error diffusion matrix, an error diffusion coefficient, and setting of an application gradation section of each error diffusion matrix. As a halftone parameter in the direct binary search method, there are a pixel updating number indicating the number of times of processing to replace (exchange) a pixel, and an exchange pixel range indicating a range of pixels to replace the pixel. Also, for each halftone algorithm, a parameter for evaluating system error tolerance can be added to the halftone parameter. When generating the halftoning rule, at least one parameter among the plurality of parameters exemplified above is specified as a halftone parameter.

  The specific content of the processing function in the image processing apparatus 20 will be described later. By supplying the data of the halftone image generated by the image processing device 20 to the print control device 22, the printing of the target image is performed by the printing device 24.

  The print control device 22 controls the printing operation by the printing device 24 based on the print image data generated by the image processing device 20. The printing device 24 is an image forming unit that executes printing under the control of the printing control device 22. There are no particular limitations on the printing method in the printing apparatus 24 and the type of colorant used. As the printing apparatus 24, various printing apparatuses, such as an inkjet printing machine, an electrophotographic printer, a laser printer, an offset printing machine, a flexographic printing machine, etc. are employable, for example. The term "printing device" is understood to be synonymous with the terms printing press, printer, image recording device, image forming device, image output device and the like. Ink, toner, etc. can be used as the coloring material according to the type of the printing device 24.

  Here, an example in which an inkjet printer, which is an example of a plateless digital printer, is used as the printing device 24 will be described. In the printing system 10 according to the present embodiment, a color image can be formed using four color inks of cyan (C), magenta (M), yellow (Y), and black (K) as an example of the printing apparatus 24. Use an inkjet printer. However, the number of ink colors and the combination thereof are not limited to this example. For example, a mode in which light color inks such as light cyan (LC) and light magenta (LM) are added in addition to four colors CMYK, a mode in which special color inks such as red and green are used, and the like are also possible.

  In FIG. 1, the print control device 22 and the printing device 24 are shown in separate blocks, and signals are exchanged between them by wired or wireless communication connection, but the present invention is not limited to such a configuration. It is also possible to configure a printing device in which the control device 22 and the printing device 24 are integrally combined.

  In addition to the printing control device 22, a system including a plate making apparatus (not shown) such as a plate recorder that produces a printing plate from image data when adopting a plate-type printing machine using a printing plate as the printing device 24 It becomes composition. In this case, a plate making apparatus such as a plate recorder and its controller, and a printing machine for printing using a printing plate prepared by the plate making apparatus are connected to the telecommunication line 28. In the case of a plate type printing machine, a configuration in which the printing control device 22, the plate making device (not shown) and the printing device 24 are combined can be grasped as a "printing device" as a whole. The printing device 24 corresponds to one mode of the “image forming unit”.

  The image reading device 26 is a means for reading an image of a printed matter (printed matter) printed by the printing device 24 and generating electronic image data indicating the read image. The image reading device 26 picks up an image of a printed matter and converts the image information into an electric signal. The image pickup device (photoelectric conversion element) and the signal obtained from the image pickup device are processed to generate digital image data. And processing circuitry.

  As the image reading device 26, a scanner separate from the printing device 24 (for example, a flatbed scanner such as a so-called offline scanner available offline) can be used. Further, the image reading device 26 may be incorporated in the printing device 24. For example, a line sensor (imaging unit) for reading an image may be installed in a sheet conveyance path of the printing apparatus 24, and the line sensor may read a print image while conveying a printed matter after image formation. The line sensor for image reading installed in the paper conveyance path in the printing apparatus 24 may be called by the terms “in-line scanner” or “in-line sensor”. The image reading device 26 corresponds to one form of “image reading means”.

  The read image data of the print image generated by the image reader 26 is input to the image processor 20. The image processing device 20 has a function of analyzing read image data obtained from the image reading device 26.

<About variations of system configuration>
The functions of the DTP device 12, the database server 14, the management computer 16, the image processing device 20, and the print control device 22 can be realized by one computer or can be realized by a plurality of computers. is there. Further, there may be various forms of sharing of roles and functions for each computer. For example, the DTP device 12 and the image processing device 20 may be integrated to realize these functions with one computer, or alternatively, the functions of the image processing device 20 may be installed in the management computer 16. It is also good. In addition, a mode is also possible in which the functions of the image processing apparatus 20 and the functions of the print control apparatus 22 are realized by one computer. Furthermore, a configuration is also possible in which the functions of the image processing apparatus 20 are shared and realized by a plurality of computers.

  The number of DTP devices 12 included in this system, database server 14, management computer 16, image processing device 20, print control device 22, printing device 24, image reading devices 26, plate making devices, etc. is not particularly limited.

  Further, in this example, the form of the network system in which the DTP device 12, the database server 14, the management computer 16, the image processing device 20, the print control device 22 and the like are connected to the telecommunication line 28 is illustrated. In the practice of the invention, each element may not necessarily be connected to the communication network.

<Hardware Configuration of Image Processing Device 20>
FIG. 2 is a block diagram showing an example of the hardware configuration of the image processing apparatus 20. As shown in FIG. The image processing apparatus 20 of this example is realized using a personal computer (PC; Personal Computer). That is, the image processing apparatus 20 includes the PC main body 30, the display device 32, and the input device 34. The notation "PC" represents a personal computer, and includes various types of computers such as desktop type, notebook type and tablet type. The PC body 30 includes a central processing unit (CPU) 41, a memory 42, a hard disk drive (HDD; Hard Disk Drive) 43 as a storage device for storing and storing various programs and data, and an input interface. A communication interface unit 45 for network connection, a display control unit 46, and a peripheral device interface unit 47 are provided.

  The image reading apparatus 26 described in FIG. 1 can also be connected to the image processing apparatus 20 via the peripheral device interface unit 47 of FIG. 2.

  As the display device 32, for example, a liquid crystal display or an organic electro-luminescence (EL) display can be used. The display device 32 is connected to the display control unit 46. The input device 34 may employ various means such as a keyboard, a mouse, a touch panel, and a track ball, and may be an appropriate combination of these. In this example, a keyboard and a mouse are used as the input device 34. The input device 34 is connected to the input interface unit 44. The display device 32 and the input device 34 function as a user interface (UI). The operator (user) can input various information using the input device 34 while watching the content displayed on the screen of the display device 32, and can operate the image processing device 20, the printing device 24, etc. . In addition, it is possible to grasp (confirm) the state of the system and the like through the display device 32.

  The hard disk drive 43 stores various programs, data, and the like necessary for image processing. For example, chart data of a chart for characteristic parameter acquisition, an operation program for characteristic parameter generation, an image processing program including halftone processing rule generation processing, a halftone selection chart generation program, and the like are stored. The program stored in the hard disk drive 43 is loaded into the memory 42 and executed by the CPU 41 to function as various means defined by the program.

  The hardware configuration of the PC body 30, the display device 32, and the input device 34 illustrated in FIG. 2 is the same as that of the DTP device 12, the database server 14, the management computer 16, and the print control device 22 described in FIG. It can be adopted as a wear configuration.

<Description of Function of Image Processing Device 20>
FIG. 3 is a block diagram for explaining the function of the image processing apparatus 20 according to the first embodiment. The image processing apparatus 20 includes a control unit 50, a characteristic parameter acquisition unit 52, a characteristic parameter storage unit 54, a priority parameter storage unit 56, a halftone processing generation unit 58, and a halftone processing rule storage unit 60. Prepare.

  The control unit 50 controls the operation of each unit in the image processing apparatus 20. The characteristic parameter acquisition unit 52 is a unit that acquires characteristic parameters related to the characteristics of the printing system 10 including the printing apparatus 24 described with reference to FIG. 1. The characteristic parameters relating to the characteristics of the printing system include, in the case of an inkjet printing system, for example, resolution, number of nozzles, ink type, average dot density, average dot diameter, average dot shape, dot density of each printing element, dot diameter, dot shape , Dot formation position deviation, non-ejection, landing interference, and the like. Information on at least one, preferably a plurality of parameters exemplified herein is acquired through the characteristic parameter acquisition unit 52. The dot formation position deviation is a concept that comprehensively represents the deviation of the position where dots are actually formed with respect to the ideal dot formation position where dots are to be formed. The “ideal position at which a dot is to be formed” is a design target position and indicates a dot formation position under an assumption that there is no error. There are various causes of dot formation position deviation. For example, the discharge direction of each printing element is curved, the discharge speed variation of each printing element, the discharge timing deviation of each printing element, the forward direction scan and the backward direction in bidirectional scan Deviation of ejection timing of scan, deviation of position of forward scan and backward scan in bidirectional scan, curve of eject direction of forward scan and backward scan in bidirectional scan, and each scan pass in multiple scan passes There may be a deviation in ejection timing, a deviation in position of each scanning pass, or a bending in the ejection direction of each scanning path. The dot formation position deviation occurs due to the factor including at least one of the factors exemplified here. In addition, the thing of "the bending of a discharge direction" of a nozzle is called "discharge bending."

  The printing element refers to a printing element responsible for printing dots in the printing device 24. In the case of an inkjet printing apparatus, a nozzle for ink ejection in an inkjet head corresponds to a "printing element". In the case of a printing apparatus using a relief, the relief of the convex portion of the halftone dots in the plate corresponds to the "printing element".

  The characteristics of the printing system include at least one of individual recording characteristics of the plurality of printing elements and characteristics common to the plurality of printing elements. The individual recording characteristics of the printing element include at least one of dot density, dot diameter, dot shape, dot recording position error, and unrecordable abnormality. In the case of the ink jet printing apparatus, the dot recording position error corresponds to the “dot formation position shift”, and the unrecordable abnormality corresponds to the “non-ejection”.

  The “common characteristics” of the plurality of printing elements include at least one of an average dot density, an average dot diameter, an average dot shape, and landing interference.

  The characteristic parameter acquisition method according to the present embodiment outputs the characteristic parameter acquisition chart by the printing device 24 and reads the characteristic parameter acquisition chart by the image reading device 26 (see FIG. 1) such as an inline scanner or an offline scanner. The read image is analyzed to acquire each parameter.

  Resolution, nozzle number, ink type, average dot density, average dot diameter, average dot shape, dot density of each printing element, dot diameter, dot shape, dot formation position deviation, non-ejection, landing interference, etc. exemplified as characteristic parameters Among the items, the resolution, the number of nozzles, and the ink type are characteristic parameters related to the system specification.

  Therefore, as for characteristic parameters related to these system specifications, it is preferable to hold the parameters in advance in the system. Then, based on the characteristic parameters relating to these system specifications, based on the resolution, the number of nozzles, and the ink type, data of a characteristic parameter acquisition chart for acquiring parameters relating to the individual system characteristics is generated or held in advance in the system. Select from the data of the plurality of characteristic parameter acquisition charts, output the characteristic parameter acquisition chart by the printing device 24 of the printing system 10, and obtain the characteristic parameter acquisition chart from the image reading device 26 (see FIG. 1) Is preferably read to obtain various characteristic parameters relating to the characteristics specific to the printing apparatus 24.

  Other characteristic parameters relating to the system specification include drop type, unidirectional scan or bidirectional scan, scan speed, paper transport amount, ejection frequency, etc., and at least one of the system specifications including these It is preferable that the data of the chart for characteristic parameter acquisition be generated based on the characteristic parameter.

  The image processing apparatus 20 of this example includes a characteristic parameter acquisition chart generation unit 62 and an image analysis unit 64 as means for automatically acquiring the characteristic parameters related to the characteristics of the printing system 10.

  The characteristic parameter acquisition chart generation unit 62 is a processing unit that generates chart data of a characteristic parameter acquisition chart including a pattern for acquiring a characteristic parameter related to the characteristic of the printing system. The chart data generated by the characteristic parameter acquisition chart generation unit 62 is sent to the print control apparatus 22 (see FIG. 1) through the data output unit 66, and the characteristic parameter acquisition chart is printed by the printing apparatus 24.

  The combination of the characteristic parameter acquisition chart generation unit 62 and the configuration for outputting the characteristic parameter acquisition chart by the printing device 24 (see FIG. 1) based on the chart data generated by the characteristic parameter acquisition chart generation unit 62 is “ This corresponds to one mode of the chart output means for characteristic parameter acquisition. Further, the characteristic parameter acquisition chart generation unit 62 corresponds to one form of “characteristic parameter acquisition chart generation means”.

  An example of the characteristic parameter acquisition chart will be described later in detail, but the characteristic parameter acquisition chart can be, for example, a single dot pattern of each printing element by the head of each color of ink. The single dot pattern is a pattern in which each dot is individually isolated without being superimposed on the other dots, and deposited as a single dot individually. By reading the chart of such a single dot pattern, it is possible to read parameters relating to dot density, dot diameter, dot shape, dot formation positional deviation, and non-ejection of each printing element.

  In addition to the single dot pattern, the characteristic parameter acquisition chart can include a continuous dot pattern in which a plurality of dots overlap. As the continuous dot pattern, the distance between dots of two dots can be changed to include a continuous dot pattern in which droplets are deposited so that parts of the dots overlap each other. Such a continuous dot pattern is used to acquire a parameter of the amount of dot deformation due to landing interference.

  When the type of droplet of the printing system 10 is one type, one type of dot may be separately deposited to form a single dot pattern, and a plurality of overlapping types may be deposited to form a continuous dot pattern. When there are a plurality of droplet types, each type of dot is separately deposited to form a single dot pattern, and a plurality of combinations of dots of each type are deposited to form a continuous dot pattern.

  When outputting the characteristic parameter acquisition chart, a single dot of the same printing element is printed multiple times, and the dot density, dot diameter, dot shape, average value of dot formation position deviation, dot density of the printing element, The dot diameter, dot shape, or dot formation position deviation may be used. Furthermore, the dot density, dot diameter and dot shape of each printing element may be averaged to obtain the average dot density, average dot diameter and average dot shape.

When the resistance design for system errors, the variance sigma ² showing a variation from the average value of the obtained measurement values by reading the characteristic parameter acquisition chart calculated, the standard deviation sigma is the square root of the variance sigma ² The value of may be taken as a predetermined amount of error to be used later.

  The print result of the characteristic parameter acquisition chart printed by the printing device 24 is read by the image reading device 26, and data of a read image of the characteristic parameter acquisition chart is obtained.

  The image analysis unit 64 functions as a characteristic parameter generation processing unit that analyzes the read image read by the image reading device 26 and generates information of the characteristic parameter. The image analysis unit 64 automatically obtains information of the characteristic parameter from the characteristic parameter acquisition chart. The image analysis unit 64 corresponds to one form of “image analysis means”.

  That is, the characteristic parameter acquisition unit 52 in the image processing apparatus 20 is configured to automatically acquire the characteristic parameter from the measurement result of the analysis of the read image of the characteristic parameter acquisition chart. The combination of the image analysis unit 64 and the characteristic parameter acquisition unit 52 corresponds to one form of “characteristic parameter acquisition means”.

  The information of the characteristic parameter acquired through the characteristic parameter acquisition unit 52 is stored in the characteristic parameter storage unit 54. The characteristic parameter storage unit 54 can hold characteristic parameters relating to system specifications in advance.

  A halftone processing rule that defines processing contents of two or more types of halftone processing having different balances of priorities with respect to a plurality of required items required for halftone processing based on the characteristic parameter. Generate The image processing apparatus 20 includes an image quality evaluation processing unit 74 including a simulation image generation unit 68 and an evaluation value calculation unit 70. The halftone processing generation unit 58 cooperates with the image quality evaluation processing unit 74 to perform two or more types. Generate halftoning rules for The halftone processing generation unit 58 corresponds to one form of “halftone processing generation means”. The evaluation value calculation unit 70 corresponds to one form of “evaluation value calculation means”. The image quality evaluation processing unit 74 corresponds to one mode of the “image quality evaluation unit”.

  The image quality evaluation processing unit 74 performs an optimization search process in which the evaluation value is improved while repeating the generation of the simulation image and the calculation of the evaluation value of the image quality with respect to the simulation image. The halftone parameter is determined by the processing by the image quality evaluation processing unit 74.

  The plurality of types of halftone processing rules generated by the halftone processing generation unit 58 are registered in the halftone processing rule storage unit 60. In FIG. 3, for convenience of illustration, two different halftone processing rules 1 and 2 are generated, and the halftone processing rules 1 and 2 are stored and stored in the halftone processing rule storage unit 60. When K is an integer of 2 or more, plural types of halftone processing rules of K or more may be generated. Then, all or part of the generated K types of halftone processing rules 1, 2,... K can be registered in the halftone processing rule storage unit 60 as a lineup. The halftone process rule storage unit 60 corresponds to one mode of halftone registration means. In the halftone processing rule storage unit 60, a plurality of types of halftone processing rules can be registered as candidates for halftone processing usable in the printing system 10. Among the plurality of halftone processing rules generated by the halftone processing generation unit 58 in this manner, the halftone processing rule to be used for actual printing is determined.

  The image processing apparatus 20 according to the present embodiment includes a halftone selection chart generation unit 76 as selection support means for selecting any one halftone processing rule from among a plurality of halftone processing rules.

  The halftone selection chart generation unit 76 generates chart data of a halftone selection chart in which print results of halftone images obtained by each of two or more types of halftone processing rules are arranged in a contrastable manner. The chart data generated by the halftone selection chart generation unit 76 is sent to the print control apparatus 22 (see FIG. 1) through the data output unit 66, and the printing apparatus 24 prints the halftone selection chart.

  The combination of the halftone selection chart generation unit 76 and the printing device 24 corresponds to one mode of “halftone selection chart output unit”.

  The user can view the output result of the halftone selection chart and select a desired halftone processing rule. The selection operation of the halftone processing rule by the user is performed using the input device 34. The input device 34 functions as "halftone selection operation means" for the user to perform an operation of selecting a desired halftoning rule. That is, the input device 34 receives a user's operation for selecting one of the halftone processing types from among the two or more types of halftone processing used to generate the halftone selection chart. It functions as a selection operation means.

  Further, not only the user can select the halftoning rule, but also the system can automatically select one halftoning rule. In this case, it is necessary to hold in advance a priority parameter related to the priority of a plurality of request items for halftone processing. The priority parameter storage unit 56 stores a priority parameter specifying balance of priorities regarding a plurality of required items. The priority parameter storage unit 56 corresponds to an embodiment of the priority parameter storage unit.

  The priority parameter can be freely input by the user through the input device 34, and setting of balance of priority and change of setting contents can be performed. Alternatively, as the priority parameters, one or more types of selection candidates may be prepared in advance on the system. When a plurality of selection candidates for setting the priority parameter are prepared, the user can select one of the selection candidates through the input device 34 in consideration of the printing purpose, application, productivity and the like.

  By specifying the balance of the priority for the required item by the priority parameter, one optimum halftoning rule recommended on the system according to the priority parameter specified by the priority parameter storage unit 56 Can be determined uniquely. Such a function of automatic selection can be realized by the control unit 50, and the configuration of the control unit 50 responsible for the processing of such automatic selection corresponds to one mode of halftone automatic selection means.

  The input device 34 functions as a priority input unit for the user to input the setting regarding the priority for each required item. A halftoning rule (that is, a combination of a halftoning algorithm and a halftoning parameter) based on the setting of the priority according to the priority set by the user, and a priority symmetrical to the balance of the priority concerning the user setting There may be an aspect of generating a halftoning rule that is a balance of degrees and comparing the two.

  Further, there may be a mode in which a plurality of halftone processing rules are generated based on the priority set by the user by slightly shifting the balance of the priorities based on the balance of the plurality of priorities set.

  The image processing apparatus 20 has a function of performing halftone processing on data of a continuous tone image in accordance with the generated halftone processing rule. That is, the image processing apparatus 20 includes an image input unit 77, a color conversion processing unit 78, and a halftone processing unit 80.

  The image input unit 77 is an input interface unit that takes in data of a document image, and functions as an image data acquisition unit. The image input unit 77 can be configured by a data input terminal that takes in document image data from the outside or another signal processing unit in the apparatus. A wired or wireless communication interface unit may be adopted as the image input unit 77, and a media interface unit for reading and writing an external storage medium (removable disk) such as a memory card may be adopted, or these embodiments It may be an appropriate combination of

  The color conversion processing unit 78 performs color conversion processing of document image data using a color profile conforming to the format of an ICC profile according to the International Color Consortium (ICC), and is suitable for output by the printing apparatus 24. To generate a color image signal. When the four color inks of CMYK are used in the printing apparatus 24, the color conversion processing unit 78 generates a CMYK image signal. In addition, when using six colors of ink including light magenta (LM) and light cyan (LC) in addition to CMYK, the color conversion processing unit 78 generates an image signal including each color component of CMYK, LM, and LC. .

  The halftone processing unit 80 performs halftone processing on the continuous tone image of each color using the halftone processing rule generated by the halftone processing generation unit 58 to generate a halftone image. The halftone image data generated by the halftone processing unit 80 is sent to the print control device 22 (see FIG. 1) through the data output unit 66, and printing is performed by the printing device 24.

  The method of obtaining a printed matter by printing on a printing medium by the printing device 24 based on the halftone image generated through the processing by the halftone processing unit 80 can be grasped as a method of producing a printed matter.

  Further, the image quality evaluation processing unit 74 of the image processing apparatus 20 can calculate the evaluation value of the print halftone image in cooperation with the halftone processing unit 80. The information of the evaluation value regarding the halftone image generated by the halftone processing unit 80 can be displayed on the screen of the display device 32, and can be provided to the outside through the data output unit 66.

<Determination procedure of halftone processing rule in printing system>
The method of determining the halftone processing rule in the printing system 10 of the present embodiment will be described in detail. FIG. 4 is a flowchart showing an example of a method of generating halftone processing rules in the present embodiment.

  First, in order to obtain characteristic parameters related to the characteristics of the printing system 10, a characteristic parameter acquisition chart is generated, and the characteristic parameter acquisition chart is output by the printing apparatus 24 (see FIG. 1) (step S10 in FIG. 4). Step S10 corresponds to one mode of the “characteristic parameter acquisition chart output process”.

  Next, the characteristic parameter acquisition chart output in step S10 is read (step S11). In step S11, the printed matter of the chart for characteristic parameter acquisition is read by the image reader 26 (see FIG. 1), and a read image of the chart for characteristic parameter acquisition is obtained. Step S11 in FIG. 4 corresponds to one mode of the “image reading process”.

  Next, the read image acquired in step S11 is analyzed to acquire a characteristic parameter related to the characteristic of the printing system (step S12). Step S12 is an example of the “characteristic parameter acquisition process”.

  Next, two or more types of halftone processing rules having different priorities of request items for halftone processing are generated (step S14). When generating the halftone processing rules, multiple types of halftone processing rules are generated based on the priority parameters and the characteristic parameters. Step S14 is an embodiment of the halftone processing generation step.

  Then, a halftone selection chart is output using the generated halftone processing rules (step S16). Step S16 is an example of the "halftone selection chart output step".

  The user can view the output result of the halftone selection chart and select any one halftone processing rule. Based on the user's selection operation, a halftone processing rule to be used for printing is determined (step S18). That is, step S18 accepts the user's operation for the user to select one of the halftone processing types from among the two or more types of halftone processing used to generate the halftone selection chart, and the selection by the user is performed. Halftoning rules are determined based on the operation. Step S18 is an example of the halftone selection operation process.

<Example of Characteristic Parameter Acquisition Chart>
A specific example of the chart for characteristic parameter acquisition used in the characteristic parameter acquisition process described in step S12 of FIG. 4 will be described.

  FIG. 5 is a diagram showing an example of the characteristic parameter acquisition chart 100. As shown in FIG. Here, single dot patterns 102C, 102M, 102Y, and 102K, and a first continuous dot pattern 104C, are formed on the print medium 101 by the nozzles that are print elements in the print head of each color of cyan, magenta, yellow, and black. It is shown that the droplets 104M, 104Y, 104K and the second continuous dot patterns 106C, 106M, 106Y, 106K are deposited. The single dot patterns 102C, 102M, 102Y, and 102K are patterns of discrete dots recorded discretely in an isolated state in which a single dot is separated from other dots. The first continuous dot patterns 104C, 104M, 104Y, and 104K and the second continuous dot patterns 106C, 106M, 106Y, and 106K are patterns of continuous dots recorded by bringing two or more dots into contact with each other.

  The single dot patterns 102C, 102M, 102Y, 102K, the first continuous dot patterns 104C, 104M, 104Y, 104K, the second continuous dot patterns 106C, 106M, 106Y, 106K are all “for obtaining characteristic parameters. Corresponds to one form of “pattern”. The single dot patterns 102C, 102M, 102Y, and 102K correspond to one form of “pattern of discrete dots”. The first continuous dot patterns 104C, 104M, 104Y, and 104K and the second continuous dot patterns 106C, 106M, 106Y, and 106K correspond to one form of “a pattern of continuous dots”.

  FIG. 6 is a schematic plan view of a serial scan type ink jet printing apparatus used for drawing the characteristic parameter acquisition chart of FIG. In FIG. 6, for convenience of illustration, only the four nozzles of each color are shown by reducing the number of nozzles of the recording head of each color. Various designs are possible for the number of nozzles, the arrangement form of the nozzles, and the nozzle density.

  As shown in FIG. 6, the head unit 110 in the serial scan type inkjet printing apparatus includes a cyan recording head 112C for ejecting cyan ink, a magenta recording head 112M for ejecting magenta ink, and a yellow recording for ejecting yellow ink. A head 112Y and a black recording head 112K for discharging black ink are mounted on a carriage 114, and are configured to be reciprocally movable along the X direction in FIG. The Y direction orthogonal to the X direction is the transport direction of the print medium 101. The X direction corresponds to the "main scanning direction", and the Y direction corresponds to the "sub scanning direction".

  The detailed structure of each recording head of cyan recording head 112C, magenta recording head 112M, yellow recording head 112Y, and black recording head 112K is not shown, but each ink jet recording head discharges ink corresponding to each nozzle. An ejection energy generating element (for example, a piezoelectric element or a heating element) that generates the necessary ejection energy is provided. Each recording head (112C, 112M, 112Y, 112K) discharges ink droplets on demand in accordance with a drive signal and a discharge control signal supplied from the print control device 22 (see FIG. 1).

  By performing droplet ejection from each nozzle 118C of the cyan recording head 112C at an appropriate timing while moving the carriage 114 in FIG. 6 in the X direction, it is possible to form a single dot pattern indicated by reference numeral 102C in FIG. . After drawing a single dot pattern 102C with cyan ink, the print medium 101 is transported in the Y direction, the recording area on the print medium 101 is changed, and then the cyan recording is performed at an appropriate timing while moving the carriage 114 in the X direction. By performing droplet deposition from each nozzle 118C of the head 112C, it is possible to form a first continuous dot pattern indicated by reference numeral 104C in FIG. Also, after drawing the first continuous dot pattern 104C with cyan ink, the print medium 101 is transported in the Y direction, the recording area on the print medium 101 is changed, and then the cyan recording is performed while moving the carriage 114 in the X direction. By performing droplet ejection from each nozzle 118C of the head 112C at an appropriate timing, it is possible to form a second continuous dot pattern indicated by reference numeral 106C in FIG.

  The setting of the inter-dot distance between overlapping dots is different between the first continuous dot pattern 104C and the second continuous dot pattern 106C. By recording plural kinds of continuous dot patterns while changing the inter-dot distance, it becomes possible to grasp the characteristic parameter regarding the relationship between the inter-dot distance d and the amount of change due to the influence of the landing interference.

  Although FIG. 5 exemplifies two types of continuous dot patterns (104C, 106C) in which distances between dots are different, three or more types of continuous dot patterns may be formed by changing the distance between dots. .

  Subsequently to the recording of the dot pattern (102C, 104C, 106C) by cyan ink, similarly, the droplet ejection by each nozzle 118M of the magenta recording head 112M, the droplet ejection by each nozzle 118Y of the yellow recording head 112Y, the black recording head 112K By sequentially performing droplet deposition by each of the nozzles 118 K, the characteristic parameter acquisition chart 100 shown in FIG. 5 is generated.

From the single dot patterns 102C, 102M, 102Y, and 102K of each color, it is possible to obtain information on dot density, dot diameter, dot shape, dot formation position deviation, and non-ejection for each printing element of each color. Also, by statistically processing the measurement results of a large number of single dots, it is possible to obtain an average dot density, an average dot diameter, an average dot shape, and respective standard deviations σ (square roots of variance σ ² ). The standard deviation σ or variance σ ² calculated for at least one of the dot density, dot diameter, dot shape, and dot formation position deviation of each printing element is equivalent to one of “dispersion information on dot dispersion” Do.

  Further, information on characteristic parameters relating to landing interference can be obtained from the first continuous dot patterns 104C, 104M, 104Y, and 104K of the respective colors and the second continuous dot patterns 106C, 106M, 106Y, and 106K. The characteristic parameter relating to landing interference refers to information relating to a change in inter-dot distance, a change in dot density, a change in dot shape, and the like due to the influence of landing interference which is interaction between overlapping dots.

<About the characteristic parameter about impact interference>
7 and 8 are explanatory diagrams of characteristic parameters relating to landing interference. The left column in FIG. 7 shows that the setting value of the distance between dots of two dots when making two dots partially overlap and continuously depositing droplets is made different in three steps of d1, d2, d3. The right column of FIG. 7 shows that the dot-to-dot distance changes due to the influence of landing interference when droplet deposition is performed with each setting of the dot-to-dot distances d1, d2 and d3. Here, the distance between dots means the distance between centers of dots.

  As illustrated, the actual inter-dot distances are u1, u2, u3 (u1> u2> u3) for the inter-dot distances d1, d2, d3 (d1> d2> d3) as set values. Since the dots are attracted by landing interference, d1> u1, d2> u2, d3> u3.

  By changing the setting of the inter-dot distance and acquiring data of the change in the inter-dot distance due to the influence of the landing interference, landing interference data as shown in FIG. 8 can be obtained. The horizontal axis in FIG. 8 is the set value of the inter-dot distance, and "R" indicates the radius of the dot. The vertical axis in FIG. 8 indicates the amount of change in inter-dot distance due to the influence of landing interference, and indicates the absolute value of | di−ui | in FIG. 7 (i = 1, 2, 3). “2R” on the horizontal axis of FIG. 8 indicates a position at which two dots circumscribe each other. If the distance between dots is larger than 2R, the dots do not overlap, and therefore they are not affected by landing interference. When the setting of the inter-dot distance is smaller than 2R, the dots overlap each other, the dots are attracted by landing interference, and the inter-dot distance changes.

  Although “the amount of change in inter-dot distance” is described in FIG. 8, the influence of landing interference can also be measured as a change in dot density or a change in dot shape.

  From the reading results of the first continuous dot patterns 104C, 104M, 104Y, and 104K and the second continuous dot patterns 106C, 106M, 106Y, and 106K in the characteristic parameter acquisition chart 100 described with reference to FIG. The parameterized landing interference data can be obtained as

  Parameters relating to such landing interference are obtained for each printing element (here, for each nozzle) and averaged. The values averaged for each color may be held separately for each color, or the values averaged for all colors may be held as a common parameter.

  Although FIG. 5 exemplifies a single dot pattern and a continuous dot pattern when it is assumed that there is one drop type for each color of CMYK, when there are a plurality of drop types, each type of dot is separately deposited to form a single drop. A single dot pattern is formed, and a plurality of combinations of dots of each type are deposited to form a continuous dot pattern. And the parameter regarding landing interference will be acquired about the combination of each droplet type. Alternatively, a plurality of combinations of C, M, Y, and K dots may be deposited to form a continuous dot pattern, and parameters regarding landing interference may be acquired for combinations of the respective colors.

  As a chart for acquiring parameters relating to the landing interference, not only the inter-dot distance of the plurality of dots may be changed, but also a chart in which the recording time difference of the plurality of dots is changed may be output. For example, as a time difference for printing a plurality of dots, a time difference between a plurality of levels is set in one pass, 2 passes, 3 passes, etc., and the dots are brought into contact with each other. You may output a chart. The recording time difference corresponds to the droplet deposition time difference.

  For example, two dots formed by overlapping and depositing the first continuous dot pattern and the second continuous dot pattern of each color of CMYK in FIG. The continuous dot pattern in which droplets are continuously ejected in one X direction movement is formed, and after the dots 1 are ejected in the first movement in the X direction of the carriage 114, the printing medium 101 is not transported in the Y direction. A continuous dot pattern in which dots 2 are ejected by the second movement of the carriage 114 in the X direction, and after the dots 1 are ejected by the first movement of the carriage 114 in the first X direction, the printing medium 101 is not transported in the Y direction. , And a continuous dot pattern in which the dots 2 are deposited by the third movement of the carriage 114 in the X direction, and so on, with a plurality of time differences (pass differences). Continuous dot pattern contacting the sheet 1 and dot 2 may be formed.

<Requirements for Halftone Processing>
The requirements required for halftone processing are, for example, as follows. That is, the first category (a) of the required items includes image quality, system cost, halftone generation time, and halftone processing time. As the second category (b) of the requirement items, regarding the image quality, there are "granularity" and "resistance to system error". These multiple requirements are in a trade-off relationship. Also, among the tolerances to system errors, there is "resistance to environmental changes". With regard to the resistance to environmental fluctuations, for example, it is conceivable to design the halftone processing rule by simulating the influence of the temperature and humidity because the ink density and the amount of spread of the dot change.

  In this embodiment, halftone processing rules of two or more types of halftone processing having different balances of priorities with respect to a plurality of request items required for halftone processing are generated. As “a plurality of request items”, At least two items of image quality, system cost, halftoning time, halftoning time, tolerance to system error, and tolerance to environmental fluctuation, which are exemplified above, are included.

<Halftone algorithm and pros and cons for each requirement item>
The advantages and disadvantages of the various halftone algorithms with respect to the image quality, system cost, halftone generation time and halftone processing time requirements in the first category (a) are as shown in the table of FIG. Here, as the halftone algorithm, three types of a dither method, an error diffusion method, and a direct binary search (DBS) method are compared.

  The system cost includes the cost related to central processing unit (CPU) performance, memory capacity, and other system specifications required to realize the halftone processing function. The halftone generation time is the time required to generate a halftone processing rule, and includes, for example, the time required to calculate halftone parameters. The halftone processing time is a time required for processing for converting data of a continuous tone image into data of a halftone image using the generated halftone processing rule.

  Compared with the three types of halftone algorithms of dithering, error diffusion, and DBS, dithering is relatively low in image quality, DBS is relatively high in image quality, and error diffusion is The image quality is intermediate between the two. In terms of system cost, dithering is relatively low and DBS is relatively expensive. The system cost of error diffusion is an intermediate level between dither and DBS. In terms of halftone generation time and halftoning time, the dither method is relatively short, and the DBS method is relatively more time consuming. Error diffusion is an intermediate level between dither and DBS.

  Further, not only the relative merits and demerits due to the type of the halftone algorithm shown in FIG. 9 but also with the same halftone algorithm, the merits and demerits for each requirement item change due to the setting of the halftone parameter. For example, when the halftone algorithm is dithering, the larger the dither mask size, the higher the image quality, but the higher the system cost and the longer the halftone generation time and the halftone processing time.

  When the halftoning algorithm is an error diffusion method, the image quality is higher as the error diffusion matrix size is larger and as the division of the gradation section to which the error diffusion matrix is applied is larger, the image quality is higher. The system cost is high, and the halftoning time and halftoning time are long.

  When the halftone algorithm is the DBS method, the higher the number of pixel updates and the wider the exchange pixel range, the higher the image quality, but the higher the system cost for other requirements, and Halftone generation time and halftoning time become long.

  Regarding the second category (b) of the requirement items, errors occur in the characteristic parameters such as dot density, dot diameter, dot shape, dot formation position deviation, non-ejection etc. depending on printing order, printing pass, timing of droplet deposition, etc. On the other hand, although it is possible to design a tolerance to system errors so as to suppress the reduction of granularity and the occurrence of streaks, the tolerance design reduces the granularity in the absence of errors. That is, the granularity and the tolerance to system errors are in a trade-off relationship.

  The printing order that can cause a system error is, for example, the overlapping order of ink colors. Also, the printing order can include the order of the forward pass and the return pass in serial scan type head scanning. The pass is the order of passes in the drawing mode in which drawing is completed by multipass with a serial scan type inkjet head. In the case of a single pass printer, one row in the main scanning direction corresponds to "pass". The timing is, for example, a case in which, when printing is performed while feeding the printing medium, an error is generated in the landing position, the dot shape, etc. depending on the timing of the deposition due to the influence of the printing medium conveyance error. It is a thing.

  Other system errors are considered to be errors because characteristic parameters such as dot density, dot diameter, dot shape, dot formation position deviation, non-ejection and the like change as the printing element changes with time. . In addition, it is difficult to accurately parameterize and reproduce the change in dot density, shape and position due to the influence of landing interference only from the chart for characteristic parameter acquisition as shown in FIG. 5, and this deviation from reality is also a system error It is regarded as

  In other words, the difference between the simulation image and the reality caused by the change of the system with time, the characteristic parameter acquisition chart, the restriction of the image reading device 26, the limit of the simulation model, etc. is regarded as a system error. The design is made to optimize the graininess, and to make the image resistant to the deterioration of graininess and streaks in the actual image even if there is such a deviation.

  In the case of the dither method, for example, in the case of a printing system in which each printing element is independently present in a wide range in the width direction of the printing medium such as a single pass printer, dot density, dot diameter, dot shape of each printing element It is difficult to perform halftone design in which the graininess is optimized by directly reflecting characteristics such as dot formation positional deviation or non-ejection.

  Therefore, also in this case, the graininess is optimized based on the information of the average dot density, dot diameter and dot shape for each ink type, and the dot density, dot diameter and dot shape according to the individual characteristics of a plurality of printing elements The design is made to be resistant to errors such as dot formation position deviation or non-ejection.

<Description by example>
The image processing apparatus 20 of the present example sets two or more types of halftone processing rules in accordance with the priorities of the respective required items, based on the above-described gains and losses for the respective required items. Halftoning rules are specified by the combination of the halftoning algorithm and the halftoning parameters.

  [Setting Example 1] As an example of setting priority, for example, when priority is given to image quality for the first classification (a) and granularity is set for the second classification (b), setting of the priority The following halftone processing rules can be defined as the halftone processing rules corresponding to (Setting Example 1).

Halftoning algorithm: DBS method Halftone parameter: large number of pixel updates = and large exchange pixel range = large system tolerance against system error: none Note that a specific numerical value or the number specifying the number of pixel updates for halftone parameters As a specific numerical value for specifying the replacement pixel range, an appropriate numerical value belonging to a relatively large value among a plurality of numerical value candidates that can be selected on the system is set.

  As for the DBS method, the halftone processing rule is determined only by specifying the number of pixel updates and the replacement pixel range as the halftone parameter.

  [Setting Example 2] As another setting example of the priority, for example, in the case where emphasis is placed on halftone processing time for the first category (a) and system error tolerance for the second category (b). The following halftone processing rule can be defined as the halftone processing rule corresponding to the setting of the priority (setting example 2).

-Halftoning algorithm: Dither method-Halftone parameter: Dither mask size = small-System error tolerance design: Add an error of ± 10 micrometers [μm] and also take into consideration the tolerance of "stripe" Parameter α for graininess evaluation Set to 1 and streak evaluation parameter β = 1.

  As a specific numerical value for specifying the dither mask size related to the halftone parameter, an appropriate numerical value belonging to a relatively small value out of a plurality of numerical values selectable on the system is set. In the setting example 2 in the above example, the degree of the system error may not be known for the second classification (b), and how the system error affects the graininess and streak quality of the actual image Because it is unknown, multiple settings may be made according to the system error tolerance priority. For example, a plurality of error amounts may be set as “± 10 micrometers [μm]”, “± 20 micrometers [μm]”. Regarding the simulation of landing interference, “setting not to be implemented”, “setting to be implemented”, “setting to simulate only dot movement due to landing interference when performing”, “simulating not only dot movement but also dot density and shape change You may set more than one. Regarding the setting of the dot movement due to the impact interference and the change of the density and the shape, a plurality of parameters may be changed based on the parameters acquired from the characteristic parameter acquisition chart.

  In addition, when performing simulation in consideration of landing interference, dot movement and / or dot deformation due to landing interference may be given not only as a function of the distance between dots, but also as a function of time.

  Not limited to the setting examples 1 and 2 in the above example, it is possible to generate halftone processing rules corresponding to various priority settings.

  When the dither method or the error diffusion method is selected as the halftone algorithm, processing for generating halftone parameters corresponding to each halftone algorithm is performed according to the flowchart shown in FIG.

FIG. 10 is a flowchart related to halftone parameter generation processing. The flowchart of FIG. 10 is a flowchart common to both the dither method and the error diffusion method.
Here, the dither method will be described as an example.

  First, halftone parameters are temporarily set (step S22). In the case of the dither method, defining the matrix size of the dither mask (that is, the dither mask size) and each threshold value corresponds to defining the halftone parameter. There may be various sizes for the dither mask size, such as 32 × 32, 64 × 64, 128 × 128, 256 × 256, and so on. The halftone parameter when the dither mask size is specified indicates the dither mask threshold value, and the flowchart of FIG. 10 is repeated from the threshold value 0 to the maximum value.

  After the halftone parameters are temporarily set in step S22, next, halftone processing is performed using the temporarily set halftone parameters (step S24). In the case of the dither method, this step S24 corresponds to obtaining dot ON pixels from the threshold value "0" to the current threshold value. That is, it is equivalent to obtaining a halftone image (dot arrangement) after halftone processing to which a dither mask is applied, for a single tone input image having the current threshold tone.

  Next, with respect to the halftone image obtained in step S24, a simulation image of the print image is generated by further using characteristic parameters relating to the characteristics of the printing system (step S26). In step S26, characteristic parameters relating to dot density, dot diameter, dot shape, dot formation position deviation, non-ejection, or an appropriate combination of these with respect to dot pattern data indicated by the halftone image are used. A simulation image of the print image is generated by arranging the reflected dots on the pixels of the halftone image.

  FIG. 11 is a conceptual view of a simulation image. In FIG. 11, each grid-like cell represents a pixel of image data. In the halftone image data, the cells of "dot on" pixels are displayed in a screen tone pattern, and the "dot off" pixels are shown in white.

  When generating a simulation image, dots reflecting the recording characteristics such as dot density, dot diameter, dot shape, dot formation position deviation, non-ejection, or an appropriate combination of these for each printing element responsible for recording of dot ON pixels Are arranged at the positions of the dot ON pixels.

  At this time, based on the arrangement state including the surrounding dots or the arrangement state after overlapping the dots, the dot shape after the landing interference may be calculated and rearranged from the deformation parameter of the dot shape due to the landing interference already acquired. . For example, the dot movement represented by a function of f (ya) in the Y direction due to the influence of landing interference due to the inter-dot distance ya in the "sub scanning direction" (Y direction in FIG. 11) parallel to the print medium conveyance direction. Table 2 shows a function of f (xb) in the X direction due to the influence of landing interference due to the dot distance xb in the "main scanning direction" (X direction in FIG. 11) which is a direction perpendicular to the print medium transport direction. Assuming that the dot movement occurs, the dot rearrangement is performed on the assumption that the dot shape changes due to the dot movement of f (ya) + f (xb) due to the influence of the landing interference.

The surrounding dots causing landing interference exist not only in the "sub-scanning direction" or "main scanning direction" but also in oblique directions, and are also affected by this, so that any direction not only in "sub-scanning direction" or "main scanning direction" as dot movement is generated due to the influence of landing interference by the distance between dots c _n of the surrounding dots n is expressed by a function of f (c _n) in the direction of the dots, f (ya) + f ( xb) + f _{(c 1) + f (c} 2) + ··· + f (c n) only may be repositioned by dot movement. Of course, since the influence of landing interference differs depending on the droplet type, the function f (*) varies depending on the surrounding dot type. "*" Represents a variable. Not only dot movement but also change in dot density and dot shape may occur due to landing interference, and dots may be rearranged.

The inter-dot distance c _n and the function f (*) representing the movement of dots can be treated as a vector. That is, the functions f (ya) + f (xb) representing the movement of dots described with reference to FIG. 11, and f (ya) + f (xb) + f (c ₁ ) + f (c ₂ ) +... + F (c) _The parameters ya, xb and c ₁ to c _n are treated as vectors having directions also for _{n 2} ). And the functions f (ya) + f (xb) and f (ya) + f (xb) + f (c ₁ ) + f (c ₂ ) +... + F (c _n ) are also treated as vectors having directions. .

  Here, the dot movement due to landing interference, and the change in density and shape may be given as a function that includes not only the distance between dots but also the difference in droplet deposition time between dots. That is, the function f (*) may be a function of the inter-dot distance and the drop deposition time difference between the dots.

  In FIG. 11, in order to arrange the simulation image in such a manner as to reflect the recording characteristics such as dot diameter, dot shape, dot formation position deviation, landing interference, etc., a higher resolution than halftone image data is required. For example, when the resolution of halftone image data is 1200 dots per inch [dpi] in both the main scanning direction and the sub scanning direction, the size of each cell is about 21 micrometers [μm] x 21 micrometers [μm] Assuming that the dot formation position deviation is about 3 micrometers [μm], the simulation image requires a resolution of 8400 dots per inch [dpi] of at least seven times. However, it is possible to reduce the memory capacity required for the simulation image by first arranging the dots on the high resolution simulation image and then smoothing it, and then converting it into a low resolution simulation image. That is, a high resolution simulation image is required only in the vicinity where dots are arranged, and the entire simulation image needs to be held only at a low resolution, so the memory capacity can be reduced.

  In the case of a printing system in which each printing element exists independently over a wide range in the width direction of the printing medium, such as a single pass printer, when generating a simulation image in step S26 in FIG. Instead of using the dot density, dot diameter, and dot shape information, the average value may be used as the dot density, dot diameter, and dot shape of each printing element for each ink type.

  Next, image quality evaluation is performed on the simulation image generated in step S26 (step S28 in FIG. 10).

  The image quality evaluation is performed by applying a low-pass filter such as a Gaussian filter to a simulation image or a visual transfer function (VTF) representing human visual sensitivity, and then performing frequency conversion and integrating the value, RMS granularity (Root Mean square granularity), an error with an input image, a standard deviation, or the like is calculated by calculating at least one evaluation value. The value calculated in the image quality evaluation process of step S28 is stored in the memory as the "image quality evaluation value".

  Here, when designing system error tolerance, with respect to dots of pixels of which at least one of the printing order, pass, and timing belongs to the same condition as the dot ON pixel corresponding to the current threshold of the halftone processing result, At least one error among a predetermined dot density, dot diameter, dot shape, dot formation position deviation, and non-ejection is added to generate a simulation image (step S26) and calculate the image quality evaluation value (step S26) as described above. Implement S28).

  Furthermore, when the tolerance design is performed so as to suppress not only the decrease in granularity but also the occurrence of streaks as the tolerance to the system error, the above error is added to the simulation image as the streak evaluation value, and the low pass filter After applying VTF, integration is performed in the main scanning direction, and a value obtained by performing one-dimensional frequency conversion and integration, an error from the integration value in the main scanning direction of the input image, a standard deviation, and the like are calculated. In addition, as a method of calculating quantitative evaluation value of graininess or a streak, the well-known method described in Unexamined-Japanese-Patent No. 2006-67423, Unexamined-Japanese-Patent No. 2007-172512, etc. can be used.

  In this example, the image quality evaluation value is calculated by the following equation, and the obtained value is held.

Image quality evaluation value = granularity evaluation value [no system error] + α × {granularity evaluation value [system error (+ predetermined amount)] + granularity evaluation value [system error existent (−predetermined amount)} + β × {stripe evaluation Value [system error present (+ predetermined amount)] + streak evaluation value [system error present (-predetermined amount)]} Formula (1)
The granularity evaluation value [without system error] in the formula for calculating the image quality evaluation value is a granularity evaluation value calculated from a simulation image to which no system error corresponding to a fluctuation component of the characteristic parameter is added. The granularity evaluation value [system error present (+ predetermined amount)] is a granularity evaluation value calculated from a simulation image to which a positive (positive) predetermined amount is added as a system error. The granularity evaluation value [system error (predetermined amount)] is a granularity evaluation value calculated from a simulation image to which a predetermined negative (negative) amount is added as a system error. The streak evaluation value [system error present (+ predetermined amount)] is a streak evaluation value calculated from a simulation image to which a positive (positive) predetermined amount is added as a system error. The streak evaluation value [system error present (−predetermined amount)] is a streak evaluation value calculated from a simulation image to which a negative (negative) predetermined amount is added as a system error. The coefficients α and β are evaluation parameters, the coefficient α is a granularity evaluation parameter, and the coefficient β is a streak evaluation parameter. In order to increase the tolerance to system errors, α and β are set to larger values. In particular, when it is intended to obscure not only the graininess but also the "streaks", the value of β is increased. A predetermined amount of additional error, type of additional error (density, dot diameter, dot shape, dot formation position deviation, non-ejection, landing interference) according to priority of system error tolerance already described, coefficient as evaluation parameter α and β are determined.

  The predetermined amount of additional error can be the standard deviation σ of each item such as dot density, dot diameter, dot shape, dot formation position deviation, etc. obtained by reading the characteristic parameter acquisition chart. At least one of the standard deviation of dot density, the standard deviation of dot diameter, the standard deviation of dot shape, and the standard deviation of dot formation positional deviation can be used as the predetermined amount of the additional error. It can also be done.

  The image quality evaluation value is calculated in step S28 of FIG. 10, and when the image quality evaluation value is improved, the halftone parameter is updated (step S30). In step S32, it is determined whether the processing from step S22 to step S30 has been repeated a predetermined number of times. The "predetermined number of times" in step S32 in the case of the dither method is the total number of pixels of the threshold candidate.

  If it is determined in step S32 that the repetition process has not been completed a predetermined number of times, the process returns to step S22, and the processes from step S22 to step S30 are repeated. If it is determined in step S32 that the repetition process has been completed a predetermined number of times, the process ends.

<In the case of error diffusion method>
An example in which the flowchart of FIG. 10 is applied to generation of halftone parameters of the error diffusion method will be described. In the case of the error diffusion method, the halftone parameter indicates the size of the error diffusion matrix, the diffusion coefficient, and the setting of the application gradation section of each error diffusion matrix. Here, in order to simplify the explanation, the size of the error diffusion matrix is one common size.

  By repeating the flowchart of FIG. 10 for all applied tone sections, the diffusion coefficient of the error diffusion matrix of each applied tone section is determined.

  The application gradation section of the error diffusion matrix can be divided, for example, into five stages of 0-50, 51-100, 101-150, 151-200, and 201-255 in the case of 8-bit gradation. The application gradation section may be defined in various ways, and may be equally divided into m steps as an integer m of 2 or more, or may be divided into arbitrary uneven gradation areas.

  The diffusion coefficient of the error diffusion matrix to be applied to the corresponding gradation section is temporarily set for a certain gradation section (step S22), and the input image (uniform image of single gradation) of each gradation in the corresponding gradation section is set. Halftone processing is performed (step S24 in FIG. 10), a simulation image is generated (step S26), image quality evaluation values are calculated (step S28), and the average value of each evaluation value for each gradation is taken as the image quality evaluation value. Do.

  When provisionally setting the halftone parameters in step S22, the initial value of the diffusion coefficient of the error diffusion matrix is set to 1 / matrix size. In temporary setting of the second and subsequent error diffusion matrix coefficients (step S22) when repeating the predetermined number of times, “± random number within a predetermined range” is added to each coefficient of the best error diffusion matrix up to that time The temporary setting is implemented by normalizing the coefficient sum to “1”.

  Further, as the initial value of the diffusion coefficient regarding the error diffusion matrix of the adjacent gradation section, it is preferable to use the diffusion coefficient of the error diffusion matrix of the adjacent gradation section which has already been optimized.

  The generation of the simulation image in step S26 is performed in the same manner as in the dither method. The image quality evaluation (step S28) is also performed in the same manner as the dither method. However, when performing tolerance design against system errors, each error is added to the dot of the pixel belonging to each printing order, pass and timing to generate a simulation image, and the graininess and streak evaluation value are calculated. The sum is taken as the "evaluation value". For example, the granularity evaluation value with system error is expressed by the following equation.

Granularity evaluation value [with system error]
= [Granularity evaluation value [with system error ("+ predetermined amount" error added to first group)]
+ Granularity evaluation value [with system error (“+ predetermined amount” error added to second group)] + ...
+ Granularity evaluation value [with system error (“-predetermined amount” error added to first group)]
+ Granularity evaluation value [with system error (“−predetermined amount” error added to second group)] + ...
... Formula (2)
Here, the grouping into the first group, the second group,... Indicates a pixel group belonging to the same condition regarding at least one of the printing order, the pass, and the timing. For example, in the case of the drawing mode in which drawing of eight round trips is completed, the pixel group recorded in the first pass is divided into the first group and the pixel group recorded in the second pass is sequentially grouped into the second group, The pixel group recorded in the eighth pass can be made the eighth group.

  The “predetermined amount” of the error to be added to the pixels belonging to each of the grouped groups may be the same value among the groups, or may be a different value for each group. Further, the “+ predetermined amount” and the “− predetermined amount” may have the same absolute value or may have different absolute values.

FIG. 12A shows the order of droplet deposition in the drawing mode in which drawing is performed at a predetermined recording resolution in eight scanning passes, using pass numbers. FIG. 12B is a conceptual diagram in the case of adding a predetermined amount of error to the dot of the pixel of the first pass in the case of drawing in the drawing mode shown in FIG. 12A. In FIG. 12B, an error in dot formation position deviation is given in the X direction to the dots of each pixel group ejected in the first pass. An error can be similarly applied to pixel groups of other pass numbers.

  In FIG. 13, with respect to the dots of the pixels of the third pass in the case of drawing in the drawing mode shown in FIG. 12A, an error in which the dot diameter is reduced by a predetermined amount is added. The dot diameter shown by the broken line in FIG. 13 indicates an average dot diameter without error.

Other Examples of Dithering
In the case of the dither method, not only the flow chart described in FIG. 10 but also a known void-and-cluster method may be used. FIG. 14 is the flowchart.

  First, an initial halftone image is prepared (step S42). The method of generating the halftone initial image follows the known Void-and-Cluster method. That is, in the energy image in which the filter is convoluted into a simulation image of a specific gradation, the pixel with the maximum energy value is regarded as a cluster pixel having a high dot density, and the energy minimum pixel is regarded as a void pixel with a sparse dot. By repeating the exchange of void pixels, an initial image is generated. The specific gradation is, for example, a gradation value of about 50% of the maximum density, and an initial image of gradation value "128" in the image data represented by 0-255 gradation is generated.

  Next, a simulation image is generated from the halftone image using the characteristic parameters related to the printing system (step S44). The generation of the simulation image is similar to the example described in FIG. For the simulation image generated in step S44, the filter is convoluted, and a threshold is set to the energy minimum pixel (that is, void pixel) among the undotted pixels of the halftone image, and the void pixel of the halftone image is set. Dots are set (step S46). For example, a Gaussian filter is used as a filter used when folding the filter.

  In step S48, it is determined whether or not setting of the threshold value (that is, setting of dots) has been completed for all gradations. If it has not been completed, the process returns to step S44 and the processes of steps S44 and S46 are repeated. That is, in step S46, a simulation image is generated for the halftone image to which a dot is newly added (step S44), an energy image is generated in which a filter is folded on the simulation image, and a threshold is set to the energy minimum pixel Is set (step S46).

  When the processing of all the gradations is completed in step S48, the processing of FIG. 14 is ended.

  The flowchart shown in FIG. 14 is processing in the direction of increasing the threshold value from the initial image, but a method of lowering the threshold value (i.e., gradation value) from the initial image also follows the well-known void and cluster method. That is, in the energy image in which the filter is folded into the simulation image, among the pixels to which the dot is set, the pixel with the largest energy is regarded as a cluster pixel having a high dot, and the threshold is set. Further, the processing of generating a simulation image, convolution of a filter, threshold setting and dot removal is sequentially repeated. Note that, for example, a Gaussian filter is used as a filter used when folding the filter.

  When performing tolerance design against a system error, similarly to the example described in FIG. 10, for dots of pixels for which at least one condition of printing order, pass, and timing matches the same condition as the current threshold. The simulation image is generated by adding at least one kind of error among a predetermined amount of dot density error, dot diameter error, dot shape error, dot formation position error, and non-ejection error (step S44). The filter is folded (step S46).

  Furthermore, in the case of designing streak resistance, one-dimensional energy (in the main scanning direction) obtained by adding the above-mentioned predetermined amount of error to the simulation image as streak energy and folding the filter That is, the streak energy) is calculated. Then, as energy of the entire print image, a pixel having a minimum image evaluation value shown below including the component of streak energy is searched.

Image evaluation value = energy [system error not included] + α x {energy [system error included (+ predetermined amount)] + energy [system error included (-predetermined amount)] + β x {streak energy [system error included (+ predetermined amount) )] + Streak energy [system error present (-predetermined amount)]}
・ Equation (3)
The halftone parameters in the dither method and the error diffusion method are determined by the method described in FIG. 10 and FIG. 14, and the halftone processing rule specified by the combination of the halftone algorithm and the halftone parameter is generated. Thus, multiple types of halftone processing rules are generated.

<About the halftone selection chart>
In the printing system 10 of the present embodiment, to provide a judgment material when selecting one type of halftone processing rule to be used for printing from among a plurality of types of halftone processing rules generated by the image processing apparatus 20 The halftone selection chart is output (step S16 in FIG. 4).

  The halftone selection chart is, for example, a floor in which primary colors such as cyan, magenta, yellow, and black, secondary colors such as red, green, and blue, tertiary colors, and quaternary colors are arranged at predetermined gradation steps. It can be a chart that contains different patches. In addition, the halftone selection chart is a patch in which gradation values are discretely changed in a predetermined gradation step for each color, or in combination with this patch, a gradation image in which gradation values are continuously changed is displayed. It can be configured to include.

  Furthermore, the halftone selection chart can be configured to include a patch or a gradation image of uniform density of a predetermined tone in a special color such as sky blue or pale orange. A variety of colors can be set for the "special color" type. Sky blue and pale orange are examples of colors in which graininess is particularly problematic in printed matter. In this manner, a color that is particularly emphasized in the printed matter can be set as a "special color" and can be included in the image of the halftone selection chart.

  The chart for halftone selection can be used as a judgment material when the user compares the quality of each halftone process based on the result of the halftone process shown in the chart and selects an appropriate halftone process. It is a thing.

  In order to be able to compare the quality of a plurality of types of halftone processing, it is preferable to generate a halftone selection chart in which processing results of a plurality of types of halftone processing are arranged on one sheet of print medium.

  FIG. 15 is a schematic view showing an example of a halftone selection chart. FIG. 15 shows an example of a halftone selection chart 150 in which the processing results of two types of halftone processing rules are arranged and printed on one print medium 101.

  The chart area shown on the left side of FIG. 15 is a chart showing the processing result of the first halftone processing rule (denoted as “halftone 1”), and the chart area shown on the right side is the second halftone processing rule It is a chart showing the processing result of “halftone 2”.

  In the halftone selection chart 150 of this example, regarding the halftone processing of each of the two types of halftone processing rules, the gradation range of 0 to 255 for each primary color of C, M, Y, and K is A total of 32 primary color patches 151 and 152 divided in 16 steps in “16” increments are arranged.

  In FIG. 15, for convenience of illustration, some of the gradation steps are omitted, and the number of patches is reduced. However, for each color of CMYK, the gradation values 16, 32, 48, 64, 80, 96, 112 The primary color patches 151 and 152 corresponding to the respective gradation values of 128, 144, 160, 176, 192, 208, 224, 240 and 255 are recorded. Reference numeral 151 denotes a primary color patch according to the processing result of the first halftone processing rule, and reference numeral 152 denotes a primary color patch according to the processing result of the second halftone processing rule.

  In the halftone selection chart 150, in addition to the arrangement of primary color patches 151 and 152 for each color of CMYK, gradation images 161 and 162 for each color, sky blue patches 171 and 172 with a predetermined gray level, and pale A pale orange patch 181, 182 with a predetermined gradation of orange is included. Reference numeral 161 denotes a gradation image according to the processing result of the first halftone processing rule, and reference numeral 162 denotes a gradation image according to the processing result of the second halftone processing rule. The gradation images 161 and 162 are image areas of gray-scale images in which gradation values are continuously changed in the range of gradation areas from the minimum gradation value to the maximum gradation value for primary colors of the respective colors of CMYK.

  The reference numeral 171 indicates a sky blue patch according to the processing result of the first halftone processing rule, and the reference numeral 172 indicates a sky blue patch according to the processing result of the second halftone processing rule. Reference numeral 181 denotes a pale orange patch according to the processing result of the first halftone processing rule, and reference numeral 182 denotes a pale orange patch according to the processing result of the second halftone processing rule.

  Further, the halftone selection chart 150 is printed with information on system cost, ink cost, and processing time for each halftone processing rule.

  Further, although not shown in FIG. 15, with respect to some or all of the primary color patches 151 and 152, information indicating the evaluation value of granularity and / or evaluation value of streak has an association with the patch. It may be printed. As a method of printing information in association with a patch, there are, for example, an aspect of printing information on a patch and an aspect of printing information near a patch.

  Similarly, with regard to the sky blue patches 171 and 172 and the pale orange patches 181 and 182, similarly, information and / or evaluation values of granularity evaluation values for some or all of these patches (171, 172, 181, 182) Information of evaluation values of streaks may be printed in association with patches.

  The user can select a preferred halftone processing rule by comparing the chart of the processing result according to the first halftoning rule and the chart of the processing result according to the second halftoning rule.

  Each of primary color patches 151 and 152, gradation images 161 and 162, sky blue patches 171 and 172, and pale orange patches 181 and 182 in the halftone selection chart 150 shown in FIG. 15 compares the quality of halftone processing. It is an image area for evaluation, and corresponds to one form of “image area for comparison evaluation”.

  The form of the chart is not limited to the form of the halftone selection chart 150 illustrated in FIG. Instead of or in combination with the primary color gradation images 161 and 162 illustrated in FIG. 15, gradation images of other colors such as secondary color, tertiary color, and quaternary color may be formed. Various forms are possible as to color types and layout of patches and gradation images as image areas for comparison and evaluation.

  In addition, when outputting a chart for halftone selection, in order to evaluate the system tolerance of halftone processing (reduction of graininess and suppression of streaks), the same chart is arranged on the entire surface of the drawable range of the print medium. Alternatively, the contents of the same chart may be output multiple sheets. The arrangement of arranging the same chart on the entire surface of the drawable area of the print medium is useful for evaluating the tolerance to a system error depending on the print position (print position) within the drawable area. In addition, a configuration in which a plurality of the same chart contents are output is useful when evaluating tolerance to system error over time. The “content of the same chart” is a form of the “image of the same halftone processing result”. The configuration in which the same chart is arranged and output on the entire surface of the drawable range of the print medium corresponds to one form of “a plurality of images of the same halftone processing result are output at different positions on the print medium”. The configuration in which the content of the same chart is output in a plurality of sheets corresponds to one form of the configuration in which an image of the same halftone processing is output a plurality of times at different print timings.

  In the configuration in which a plurality of sheets of the same chart are shifted in time and output the same chart continuously, halftone processing is switched to perform continuous chart output regarding a plurality of types of halftone processing. it can. In this case, it is preferable to fix the print location (print position on the print medium) of the processing result of the same halftone process. When outputting a plurality of charts of the processing result of the same halftone processing, by printing the charts in the same place of each print medium, it is possible to eliminate the influence of the system error depending on the place.

  In the case of a configuration in which a plurality of the same chart are spatially shifted and output, halftone processing results adjacent to each other on one print medium can be processing results of different types of halftone processing. Further, in the case of the configuration in which the same chart is spatially shifted and output in a plurality, the same halftone processing result can be stored in the same print medium. This can eliminate the effects of system errors over time.

  Also, as described in FIG. 15, as information useful for the judgment and selection by the user, not only the image showing the processing result of the halftone processing but also the quantitative evaluation value of granularity and streaks, the system cost At least one of the ink cost, the halftone generation time, the halftone processing time and the like may be printed on the printed matter of the halftone selection chart. The "system cost" is indicated as, for example, the cost of an additional option for enhancing the function required to realize the system specification required to keep the required halftone processing time. For “Ink cost”, the amount of ink used varies slightly depending on the type of halftone, so the ink cost is calculated from the amount of ink used for each halftone type when the same image content is printed for a predetermined number of sheets, Information is presented. At least one of the system cost and the ink cost corresponds to the "cost".

  At least one piece of information on the results of halftone processing including granularity and streak quantitative evaluation value, system cost, ink cost, halftone generation time, halftone processing time, etc. is printed at the time of output of the halftone selection chart. Instead of or in combination with the configuration presented, it may be configured to be displayed on the screen of the user interface. A configuration for printing information of evaluation values related to such quantitative evaluation together with the halftone selection chart, and a configuration for displaying the screen on the user interface correspond to one mode of the “information presenting means”. That is, the display device 32 (see FIGS. 2 and 3) of the image processing device 20 can function as the “information presenting means”.

  The graininess evaluation value or the streak evaluation value may be calculated by generating a simulation image according to the method described above from the halftone processing result of the halftone selection chart and calculating the graininess evaluation value or the streak evaluation value. The output result of the tone selection chart may be read by an image reader 26 such as an in-line scanner, and the graininess evaluation value or the streak evaluation value may be calculated from the read image.

  In addition, in order to evaluate the tolerance to a system error, at least one of the conditions of printing order, pass, and timing for the generation of the simulation image regarding the chart for halftone selection also evaluates to the dot of the pixel group belonging to the same condition. And adding a predetermined amount of error to generate a simulation image.

  When the quantitative evaluation value of graininess or streaks is calculated from the simulation image, the calculated value can be printed on the printed matter of the halftone selection chart.

  On the other hand, when the output result of the halftone selection chart is read and the quantitative evaluation value of granularity or streaks is calculated from the read image, the calculation result can be displayed on the screen of the user interface. The user can refer to the quantitative evaluation value displayed on the screen of the user interface and confirm the printed matter of the chart for halftone selection to select an appropriate halftone process.

  As another method, when the output result of the halftone selection chart is read and the quantitative evaluation value of graininess or streaks is calculated from the read image, the halftone selection chart for which the reading is performed is read. The result of the calculation may be additionally printed. Alternatively, after outputting the halftone selection chart subjected to the reading, the graininess already calculated when outputting the same halftone selection chart The configuration may be such that the quantitative evaluation value of streaks is printed.

  In the case of presenting information on the granular evaluation value or the quantitative evaluation value of streaks, particularly on the screen, regarding the difference in the evaluation value to which the user needs to draw attention, and the patch portion in which the evaluation value fluctuates. And the aspect which highlights on a printed matter is also preferable.

  For example, when a plurality of halftone selection charts are output while the print timing is shifted temporally and a change due to a change over time is confirmed, the change in the quantitative evaluation value calculated from the read image of the halftone selection chart is There is an aspect in which highlighting is performed to warn the user of the fact that the size is larger than the allowable range. In this case, the history of the quantitative evaluation value is stored in the memory, and when the amount of change of the quantitative evaluation value exceeds the allowable range, the differentiation display or other highlighting is performed.

  In addition to the system error over time, that is, the confirmation by the chart for halftone selection about the instability of the system with respect to time, the system error due to the printing position (location) on the print medium, Instability can also be checked using a halftone selection chart. Also in this case, there is a mode in which highlighting is performed to warn the user that the difference in the quantitative evaluation value due to the difference in place is large beyond the allowable range.

  Also, after one halftone processing rule is selected by the automatic selection of the system or by the user's selection operation, the priority balance of the first classification (a) and the second classification (b) of the required item is A plurality of other halftoning rules close to the selected halftoning rule are further generated, and the image quality evaluation value and the overall evaluation value are calculated based on the priority parameters, or a halftone selection chart is output, And the system or user may be able to select more optimal halftone processing rules. When the system automatically selects halftone processing, generation of halftone processing rules may be repeated until the image quality evaluation value or the total evaluation value becomes equal to or more than a predetermined threshold.

<About the chart generation method of halftone selection by DBS method>
FIG. 16 is a flowchart showing a procedure for generating a halftone image of a halftone selection chart by the DBS method. In the case of the DBS method, the halftone image of the halftone selection chart is acquired according to the flowchart of FIG. 16 based on the already determined halftone parameters.

  First, an initial halftone image is prepared (step S52). The halftone initial image is generated by subjecting the halftone selection chart to dither processing using a dither mask generated separately or by the dithering halftone processing rule generated in step S14 of FIG. 4. Ru.

  Next, processing for replacing dots in the halftone image is performed (step S54 in FIG. 16). A simulation image is generated using characteristic parameters relating to the characteristics of the printing system before and after dot substitution (step S56). The image quality of the generated simulation image is evaluated (step S58), and if the evaluation value is improved before and after replacement, the halftone image is updated (step S60). The image quality evaluation value calculated at the time of image quality evaluation in step S58 is obtained by applying a low-pass filter such as a Gaussian filter or a visual transfer function (VTF) representing human visual sensitivity to the simulation image and calculating the error (difference) from the input image. It is obtained by calculation.

  The dots are replaced a predetermined number of times in accordance with the preset "number of pixel updates", and the processing from step S54 to step S60 is repeated.

  In step S62, it is determined whether or not the process of replacing the dots a predetermined number of times has been completed. If the process of the predetermined number of times has not been completed, the process returns to step S54, and the processes of steps S54 to S60 are repeated. If it is determined in step S62 that the process has been completed a predetermined number of times, this process ends.

<Means for Compensating Image Deterioration Due to Impact of Landing Interference>
So far, in the halftone parameter generation of the dither method and the error diffusion method represented by the flowcharts of FIG. 10 and FIG. 14 or the halftone processing of the DBS (Direct Binary Search) method represented by the flowchart of FIG. In order to obtain good halftone processing results in consideration of the influence of landing interference, the explanation has been made on the assumption that a simulation image including landing interference is generated. However, since simulation of landing interference requires a great deal of time, and simulation accuracy is also a problem, it is desirable that image quality degradation due to the influence of landing interference can be compensated with a simple method without performing simulation. From this point of view, it is also one of the desirable modes to have a configuration provided with means for compensating for image quality deterioration due to landing interference at the time of dot contact.

  For example, in order to compensate for graininess deterioration due to the influence of landing interference, the movement direction and movement amount are estimated based on the type of surrounding dots, the contact direction and the contact amount for dots of each pixel, and the movement direction and / or movement amount is Based on this, each dot may be classified into small groups of the same movement direction and / or the same movement amount, and the graininess of each small group may be kept good to perform halftone parameter generation or halftone processing. Furthermore, pixels belonging to the same printing order, pass, and timing to compensate for streaks, unevenness, and graininess deterioration due to landing interference when there is a dot diameter, dot shape, dot formation position deviation, and non-ejection error. After adding at least one error of a predetermined dot diameter, dot shape, dot formation position deviation, and non-ejection to the dots of the group, the type of surrounding dots, the contact direction and the contact for the dots of each pixel of the group Estimate the moving direction and moving amount based on the amount, classify each dot into the same moving direction and / or small moving group of the same moving amount based on the moving direction and / or moving amount, and improve the granularity of each small group Halftone parameter generation may be performed or halftone processing may be performed.

  Alternatively, in order to compensate for streaks, unevenness and graininess deterioration due to landing interference when there is at least one error among dot diameter, dot shape, dot formation position deviation, and non-ejection, the same printing order, pass Even if at least one error among a predetermined dot diameter, dot shape, dot formation position deviation, and non-ejection is added to the dots of a group of pixels belonging to or timing, the contact state of the dots of the group with the surrounding dots Halftone parameter generation or halftoning may be performed to reduce the change.

<Significance of outputting a halftone selection chart>
The chart for halftone selection has a first meaning of outputting to compare processing results of two or more types of halftone processing rules, and a second meaning of outputting to confirm instability of the system, Have at least one of the following meanings. A chart configuration in which processing results of two or more types of halftone processing rules are juxtaposed on one print medium 101 is useful in the first meaning. On the other hand, when focusing on the second meaning, it is not always necessary to co-locate processing results of two or more types of halftone processing rules on one print medium 101. Rather, for the purpose of confirming the instability of the system depending on the place and the purpose of confirming the instability of the system with respect to time, only the processing result of one type of halftone processing rule is recorded in one print medium 101 It may be in the form of a chart.

<On Generation of Two or More Halftone Processing Rules and Comparison of Their Processing Results>
In this embodiment, at least two types of halftone processing rules are generated, and more preferably, more than two types of halftone processing rules are generated.

  FIG. 17 is a graph showing the qualitative tendency of various halftone processing rules when the horizontal axis is image quality and the vertical axis is system cost or halftone processing time. The image quality is improved in the order of the dither method, the error diffusion method, and the DBS method, and the system cost and the halftone processing are compared in the image method in terms of the dither method, the error diffusion method, and the DBS method. With regard to time, the cost increases and the time lengthens in the order of the dither method, the error diffusion method, and the DBS method. However, among the dither algorithm, error diffusion algorithm, and DBS algorithm, the balance between the image quality and the system cost or halftone processing time can be changed depending on the setting of the halftone parameter.

  Although various types of halftone processing with different balances of requirements can be set, in the example shown in FIG. 17, the level of “image quality” is low / medium for each of the dither method, the error diffusion method, and the DBS method. A total of nine types of settings that are different in three levels of / high are shown. D1, D2 and D3 in FIG. 17 indicate three types of settings in the dither method, ED1, ED2 and ED3 indicate three types of settings in the error diffusion method, and DBS1, DBS2 and DBS3 indicate three types in the DBS method. Indicates the type setting.

  Also, apart from the pros and cons for each requirement item dependent on the halftone algorithm described in FIG. 17, as shown in FIG. 18, the instability of the system when the graininess is improved with one parameter regardless of the halftone algorithm There is a tendency that the resistance to

  The horizontal axis in FIG. 18 represents the graininess, and the vertical axis represents the system instability. In FIG. 18, the tolerance to the instability of the system includes both the tolerance of graininess and the tolerance of streaks, but both have similar qualitative tendencies. FIG. 18 shows only the graininess tolerance. That is, as shown in FIG. 18, there is a tendency that as the granularity is increased, the system is less resistant to instability and the streak also has a reduced resistance. Conversely, at the expense of granularity, the resistance to system instability is improved and the resistance to streaks is also improved.

  As an example of setting the resistance to the instability of the system, for example, it is conceivable to perform three kinds of setting in which the level of resistance is changed to three levels of high / medium / low. T1, T2 and T3 in FIG. 18 show three kinds of settings for the resistance to system instability.

  Based on the qualitative tendency described in FIG. 17 and FIG. 18, two or more types of halftone processing rules having different balances of a plurality of requirements for halftone processing are generated. For example, a total of 27 types of halftone processing rules can be generated by default by a combination of the 9 types of settings described in FIG. 17 and the 3 types of settings regarding graininess resistance described in FIG.

  It is possible to output a halftone selection chart according to the processing result of each of the 27 types of halftone processing rules, and allow the user to select one halftone processing rule among them.

  As another method, the user designates the setting of the priority for the request item, and generates the two or more types of halftone processing rules close to the setting of the priority to reflect the user's intention in advance. It may be made to narrow down the presentation range of the type of halftone processing.

  For example, in the case where the image quality-oriented setting is specified, the setting is limited to the DBS method or the error diffusion method, and in the case of the setting that places importance on image quality and cost balance, the error diffusion method. As such, the type of halftone algorithm may be constrained in advance to generate halftone processing rules.

  Further, among the required items, for halftone processing time and cost, target quantitative required values are often assumed in advance to some extent. That is, it is considered that there are many cases where the user can set the target value in advance with respect to the target halftone processing time and cost from the requirement of productivity etc.

  Therefore, it is also possible to select a plurality of halftone processing rules out of 27 types within the range satisfying such a user side request (target value) and actually output as a halftone selection chart.

<On the selection of halftone processing>
As a method of selecting one halftone processing rule from among two or more types of halftone processing rules, the chart output of the halftone selection chart is confirmed, and the user selects any one halftone processing It is also possible to adopt a configuration in which the system automatically selects one halftoning process.

  In this case, the system holds in advance priority parameters for a plurality of requirement items. For example, with regard to the first class (a), there are requirements for image quality, system cost, halftone generation time, granularity for the second class, tolerance to system errors, and the system has the following priority parameters A, B, C, D and p, q, r are held in advance, and the comprehensive evaluation value is calculated by the following equation.

Overall evaluation value = A × image quality evaluation value + B × system cost + C × halftone generation time + D × halftone processing time image quality evaluation value = p × granularity evaluation value [no system error] + q × {granularity evaluation value [system error Yes (error addition of "+ predetermined amount" to the first group) + granularity evaluation value [system error (error of "+ predetermined amount" addition to the second group) + ... + granularity evaluation value [system error Yes (error addition of "-predetermined amount" to the first group) + graininess evaluation value [system error existence (error of "-predetermined amount" addition to the second group) + ...}
+ R × {Strain evaluation value [with system error (“+ predetermined amount” error added to first group)] + Stripe evaluation value [with system error (“+ predetermined amount” error added to second group) ”+ ... + Streak evaluation value [system error (with 1st group-'predetermined amount' error added)] + streak evaluation value [system error with (2nd group '' predetermined amount 'error added)] + ...}
... Formula (4)
Here, in order to obtain the image quality evaluation value, a simulation image is generated by the method described above from the halftone processing result of the halftone selection chart, and the graininess evaluation value and the streak evaluation value are calculated. The evaluation values are averaged for each gradation, sky blue, and pale orange.

  The granularity evaluation value and the streak evaluation value may or may not be averaged for each ink type. In order to obtain graininess and streak evaluation values against system errors, error generation is performed on dots of pixel groups (groups) that belong to the same printing order, pass, and timing for generating simulation images. Generating a simulation image.

  In addition, simulation conditions applied at the time of halftone processing generation which generates two or more types of halftone processing rules as a previous step, and one by two or more types of halftone processing rules by user selection or automatic selection of the system The simulation conditions applied during simulation image quality evaluation in halftone selection to select one halftoning rule do not necessarily match. For example, the simulation in the halftone process generation is performed under the condition not including the factor of the landing interference or in consideration of only the “dot movement” of the factors of the landing interference in order to execute the generation of the halftone processing rule promptly. The simulation is carried out under the conditions to be simulated, and the simulation in the automatic halftone selection is carried out including all the changes in dot movement, dot shape and dot density due to landing interference, in order to reproduce the real image as faithfully as possible. You may Here, “halftone processing generation” indicates generation of halftone parameters when the halftone algorithm is the dither method or error diffusion method, and generation of a halftone image in the case of the DBS method.

  In addition, the predetermined amount of the error to be added (that is, the predetermined error amount) may be an appropriate value separately or may be a standard deviation or the like calculated from the reading result of the characteristic parameter acquisition chart. .

  Alternatively, instead of calculating the evaluation value based on the simulation image described above, the halftone selection chart output by the printing device 24 is read by the image reading device 26, and the granularity evaluation value and the streak evaluation value are calculated from the read image. Then, the image quality evaluation value may be obtained by the following equation by appropriately averaging the values of the evaluation values for each color, each gradation, sky blue, and pale orange.

Image quality evaluation value = p × granularity evaluation value + r × stripe evaluation value Also, image quality evaluation value, system cost, halftone generation time, halftone processing time and granularity evaluation value [no system error], granularity evaluation value [system For each of the streak evaluation values, an allowable threshold is set, and a halftone processing rule in which each value is equal to or greater than the threshold is first extracted, and based on the above-mentioned comprehensive evaluation value, halftone processing rules are extracted. Optimal halftoning may be determined.

  For example, when it is desired to determine halftone processing whose system cost is as low as possible, the image quality evaluation value, system cost, halftone generation time, halftone processing time and granularity evaluation value [no system error], granularity evaluation value [system error existing] For each of the streak evaluation values, halftone processing which is equal to or greater than the respective allowable threshold value is first extracted, and then the priority parameter B is set to a large value to obtain a comprehensive evaluation value.

  The comprehensive evaluation value is one form of the “judgment evaluation value”. Each of priority parameters A, B, C, D, p, q, r is set to a real number representing a priority.

  In addition, after one halftone processing rule is selected by automatic selection of the system or by user's selection operation, the priority balance of the first classification (a) and the second classification (b) of the required item is A plurality of other halftoning rules close to the selected halftoning rule are further generated, and an image quality evaluation value and an overall evaluation value are calculated based on the priority parameter, or a halftone selection chart is output, These may be included to allow the system or user to select more optimal halftone processing rules. When the system automatically selects halftone processing, generation of halftone processing rules may be repeated until the image quality evaluation value or the total evaluation value becomes equal to or more than a predetermined threshold.

<Description of Function of Image Processing Apparatus According to Second Embodiment>
FIG. 19 is a block diagram for explaining the function of the image processing apparatus according to the second embodiment. Instead of the configuration of the image processing apparatus according to the first embodiment described with reference to FIG. 3, the image processing apparatus according to the second embodiment shown in FIG. 19 can be used. In FIG. 19, elements that are the same as or similar to the configuration described in FIG. 3 are given the same reference numerals, and descriptions thereof will be omitted.

  The halftone processing generation unit 58 in the image processing apparatus 20 according to the second embodiment shown in FIG. 19 includes a pre-stage halftone processing generation unit 58A and a halftone automatic selection unit 58B. The pre-stage halftone processing generation unit 58A is a halftone that defines processing contents of two or more types of halftone processing that have different balances of priorities with respect to a plurality of required items required for halftone processing based on the characteristic parameter. Generate processing rules. The halftone automatic selection unit 58B selects one of the types of halftone processing defined by the two or more types of halftone processing rules generated by the previous stage halftone processing generation unit 58A based on the priority parameter. A process of automatically selecting the type of halftone processing used for printing of 10 is performed.

  The halftone automatic selection unit 58B corresponds to one mode of "halftone automatic selection means". The halftone automatic selection unit 58B includes a determination evaluation value calculation unit 59 as one mode of the “determination evaluation value calculation means”.

  The determination evaluation value calculation unit 59 is a calculation unit that calculates a determination evaluation value for evaluating the appropriateness of the halftone process defined by the halftone process rule generated by the previous stage halftone process generation unit 58A. The determination evaluation value calculation unit 59 calculates a determination evaluation value based on the priority parameter stored in the priority parameter storage unit 56. That is, the determination evaluation value calculation unit 59 calculates an overall evaluation value which is one form of the determination evaluation value. The specific example of the comprehensive evaluation value is as described above. The halftone automatic selection unit 58B automatically selects the type of halftone processing used for printing in the printing system 10 based on the determination evaluation value calculated by the determination evaluation value calculation unit 59.

  The priority parameter storage unit 56 stores a priority parameter specifying balance of priorities regarding a plurality of required items. The step of storing the priority parameter in the priority parameter holding unit 56 corresponds to one mode of the priority parameter holding step.

  The priority parameter can be freely input by the user through the input device 34, and setting of balance of priority and change of setting contents can be performed.

  The image processing apparatus 20 further includes an image quality evaluation processing unit 74 including a simulation image generation unit 68 and an evaluation value calculation unit 70. The halftone processing generation unit 58 cooperates with the image quality evaluation processing unit 74 to perform halftoning. Generate tone processing rules. The simulation image generation unit 68 corresponds to one form of “simulation image generation means”, and the evaluation value calculation unit 70 corresponds to one form of “image quality evaluation value calculation means”.

  The image quality evaluation processing unit 74 performs an optimization search process in which the evaluation value is improved while repeating the generation of the simulation image and the calculation of the evaluation value of the image quality with respect to the simulation image. The halftone parameter is determined by the processing by the image quality evaluation processing unit 74. In addition, the simulation image generation unit 68 generates a simulation image in the case of printing a halftone image obtained by applying the halftone processing defined by the halftone processing rule generated by the previous stage halftone processing generation unit 58A. The evaluation value calculation unit 70 calculates an image quality evaluation value from the simulation image generated by the simulation image generation unit 68. The determination evaluation value calculation unit 59 of the halftone automatic selection unit 58B can calculate the determination evaluation value using the image quality evaluation value calculated by the image quality evaluation processing unit 74.

  The plurality of types of halftone processing rules generated by the previous stage halftone processing generation unit 58A are registered in the halftone processing rule storage unit 60.

  The image analysis unit 64 shown in FIG. 19 analyzes the read image of the chart for characteristic parameter acquisition and functions as means for generating the characteristic parameter, and also reads the halftone selection chart output from the printing apparatus 24. The image is analyzed to function as a means for calculating a quantitative evaluation value of a halftone image. Further, the judgment evaluation value calculation unit 59 of the halftone automatic selection unit 58B determines at least one of the granularity evaluation value and the streak evaluation value calculated based on the output result of the halftone selection chart in the image analysis unit 64. Information on the evaluation value can be acquired from the image analysis unit 64 to calculate a judgment evaluation value. The halftone automatic selection unit 58B can perform processing for automatically selecting an optimal halftone processing rule based on the quantitative evaluation value calculated from the read image of the halftone selection chart.

  FIG. 20 is a flowchart showing a method of generating halftone processing rules in a printing system provided with an image processing apparatus according to the second embodiment.

  In FIG. 20, the same step numbers are given to steps (steps) common to the steps in the flowchart described in FIG. 4 and the description thereof is omitted. In FIG. 20, the process from step S10 to step S14 is the same as that of the flowchart of FIG.

After two or more types of halftone processing rules are generated based on the characteristic parameter in step S14, one type of halftone is selected from the generated two or more types of halftone processing rules based on the priority parameter. Processing rules are determined (step S17). That is, the combination of step S14 and step S17 corresponds to one mode of "halftone process generation step". Step S14 generates two or more types of halftone processing rules as a pre-stage for obtaining one halftone process optimum for the system, and step S17 generates priority from the two or more types of halftone processing rules generated in step S14. Step-wise processing is performed to select one optimum type of power parameter.

  However, in the implementation of the present invention, the configuration is not necessarily limited to the step-by-step process steps as shown in FIG. For example, an optimization method is defined that defines an evaluation function reflecting the setting of priority parameters and searches for an optimal solution that maximizes or minimizes the evaluation value as the value of the evaluation function for the combination of the halftone algorithm and the halftone parameter. It can be used to generate one type of halftone processing rule.

  In this case, although it can be viewed that a plurality of types of halftone processing rules are generated in the process of arithmetic processing for finding an optimal solution, halftone processing is finally generated as a type of halftone processing usable in the system The rules can be interpreted as one type of halftoning rule as an optimal solution.

  Even when the system automatically selects (determines) one halftone processing rule according to the setting of the priority parameter, the user can then select the halftone processing rule determined by the automatic selection. It is good also as composition which can be changed suitably. In addition, various halftone processing rules generated by the image processing apparatus 20 can be changed so that the setting of the priority parameter can be changed by the user operation or the program of the system to reselect the halftone processing rule. It is preferable to register as a line-up.

  In addition, the information such as granularity and streak quantitative evaluation value, halftone generation time, halftone processing time, system cost, etc. for each halftone processing rule can be referred to as necessary so that they can be referred to as necessary. It is preferable to store it in association with the tone processing rule.

  Halftoning algorithm, half for each ink type, calculating image quality evaluation value, system cost, halftoning time, halftoning time for each ink color used in printing device 24, that is, for each ink type The tone parameters may be selected, the image quality evaluation value, the system cost, the halftone generation time, and the halftone processing time may be calculated for all colors, and the same common halftone algorithm for all colors and halftone parameters may be selected. May be

<Another Example of Chart for Characteristic Parameter Acquisition>
FIG. 21 is a diagram showing another example of the characteristic parameter acquisition chart. The characteristic parameter acquisition chart 200 shown in FIG. 21 is an example of a characteristic parameter acquisition chart output by a single pass printer.

  The characteristic parameter acquisition chart 200 shown in FIG. 21 includes single dot patterns 202C, 202M, 202Y, and the like printed on the print medium 201 by the nozzles that are print elements in the print head of each color of cyan, magenta, yellow, and black. 202K, first continuous dot patterns 204C, 204M, 204Y, 204K, and second continuous dot patterns 206C, 206M, 206Y, 206K.

  The single dot patterns 202C, 202M, 202Y, and 202K are patterns of discrete dots recorded discretely in an isolated state in which a single dot is separated from other dots. The first continuous dot patterns 204C, 204M, 204Y and 204K and the second continuous dot patterns 206C, 206M, 206Y and 206K are patterns of continuous dots recorded by bringing two or more dots into contact with each other.

  The single dot patterns 202C, 202M, 202Y and 202K correspond to the single dot patterns 102C, 102M, 102Y and 102K in the characteristic parameter acquisition chart 100 described with reference to FIG. The first continuous dot patterns 204C, 204M, 204Y and 204K in FIG. 21 correspond to the first continuous dot patterns 104C, 104M, 104Y and 104K in the characteristic parameter acquisition chart 100 described with reference to FIG. 21 correspond to the second continuous dot patterns 106C, 106M, 106Y, and 106K in the characteristic parameter acquisition chart 100 described with reference to FIG. However, the first continuous dot patterns 104C, 104M, 104Y, and 104K and the second continuous dot patterns 106C, 106M, 106Y, and 106K in FIG. 5 have a plurality of dots in contact with each other in the main scanning direction. While the first continuous dot pattern 204C, 204M, 204Y, 204K and the second continuous dot pattern 206C, 206M, 206Y, 206K in FIG. They differ in that they

  Also in the case of the single pass method, as in the case of the serial scan method, a plurality of continuous dot patterns are formed by changing not only the distance between two dots deposited by overlapping in the continuous dot pattern but also the droplet deposition time. May be In the case of the single pass method, it is possible to change the droplet deposition time difference between two dots of the continuous dot pattern by changing the transport speed of the print medium 201.

  FIG. 22 is a schematic plan view of the recording head portion of the ink jet printing apparatus as a single pass printer used for the output of the characteristic parameter acquisition chart 200 shown in FIG. In FIG. 22, the vertical direction from the top to the bottom is the transport direction of the print medium 201. As a means for conveying the print medium 201 (medium conveyance means), various forms such as a drum conveyance method, a belt conveyance method, a nip conveyance method, a chain conveyance method, and a pallet conveyance method can be adopted. be able to. The transport direction of the print medium 201 is referred to as “media transport direction”. In FIG. 22, the medium transport direction is indicated by an outlined arrow. The medium transport direction corresponds to the "sub scanning direction". The lateral direction in FIG. 22, that is, the direction parallel to the paper surface and orthogonal to the medium conveyance direction is referred to as the “medium width direction”. The medium width direction corresponds to the "main scanning direction".

  The inkjet printing apparatus as a single pass printer shown in FIG. 22 includes a cyan recording head 212C for ejecting cyan ink, a magenta recording head 212M for ejecting magenta ink, a yellow recording head 212Y for ejecting yellow ink, and black ink. And a black recording head 212K for discharging.

  The cyan recording head 212C, the magenta recording head 212M, the yellow recording head 212Y, and the black recording head 212K each have a plurality of nozzles arranged over the length corresponding to the maximum width of the image forming area in the medium width direction orthogonal to the medium conveyance direction. It is a line head which has the nozzle row which was done.

  Various designs are possible for the number of nozzles, the arrangement form of the nozzles, and the nozzle density in the recording heads (212C, 212M, 212Y, 212K) of each color. The print heads (212C, 212M, 212Y, 212K) of each color may have a common head design for all colors, or may have different head designs for some or each color of each print head.

Here, in order to simplify the illustration, it is assumed that the recording heads (212C, 212M, 212Y and 212K) of each color have a common structure by head design common to all colors, and each recording head (212C, 212M, 212Y and 212K) ), Only 40 nozzles are shown. Although FIG. 22 exemplifies an inkjet printing apparatus using inks of four colors of CMYK, the combination of ink colors and the number of colors is not limited to this embodiment. As described in FIG. 6, light ink, dark ink, and special color ink may be added as needed. Further, the arrangement order of the recording heads of the respective colors is not limited to the example of FIG.

  On the ink ejection surface of the cyan recording head 212C shown in FIG. 22, the plurality of nozzles for ejecting ink 218C have a row direction along the main scanning direction and a certain angle which is nonparallel and nonorthogonal to the main scanning direction. It is arranged in a regular array pattern in each direction with the oblique column direction. Here, an example of a nozzle array having a 4-row × 10-column matrix arrangement in which a row of nozzles in which four nozzles 218C are arranged at regular intervals along a diagonal row direction is formed in 10 rows with different positions in the main scanning direction. It is shown.

  In this two-dimensional nozzle array, there are four rows of row direction nozzle rows in which ten nozzles 218C are arranged at regular intervals along the row direction at different positions in the sub-scanning direction. With regard to these four rows of row direction nozzle rows, the first row, the second row, the third row, the fourth row are from the bottom of FIG. 22 to the top (that is, from the downstream side to the upstream side in the medium width direction). When line numbers are given in order of eyes, the nozzle positions in the main scanning direction are different between the first line and the second line. Similarly, the nozzle positions in the main scanning direction are different between the second and third rows, the third and fourth rows, and the fourth and first rows.

Assuming that the nozzle spacing in the main scanning direction of the nozzles 218C arranged in one row at equal intervals in the row direction nozzle row is L _N , the first and second rows, the second and third rows, and the third and fourth rows The shift amount of the nozzle position in the main scanning direction of the fourth and first rows is L _N / 4, which is a value obtained by dividing L _N by the total number of rows. Such a two-dimensional nozzle array can be considered as a nozzle array in which the nozzles 218C are arranged at equal intervals (interval of “L _N / 4”) in the main scanning direction.

  Also regarding the arrangement form of the nozzles 218M for ink discharge in the magenta recording head 212M, the arrangement form of the nozzles 218Y for ink discharge in the yellow recording head 212Y, and the arrangement form of the nozzles 218K for ink discharge in the black recording head 212K It is similar to the nozzle arrangement form of 212C.

  In general, in the case of a recording head having a two-dimensional nozzle arrangement as well as the matrix arrangement illustrated in FIG. 22, the nozzles in the two-dimensional nozzle arrangement are projected along the medium width direction (corresponding to the main scanning direction). The projected nozzle array (orthogonal projection) can be considered equivalent to a single nozzle array in which the nozzles are arranged at substantially equal intervals at the nozzle density for achieving the recording resolution in the main scanning direction (medium width direction). Here, "equally spaced" means substantially equally spaced dots that can be recorded by the ink jet printing apparatus. For example, the term "evenly spaced" is also included in the case where the spacing is slightly different in consideration of manufacturing errors and movement of droplets on the medium due to landing interference. In consideration of the projection nozzle row (also referred to as “substantial nozzle row”), the nozzle positions (nozzle numbers) can be associated in the order of the projection nozzles arranged along the main scanning direction. The number of nozzles constituting the two-dimensional nozzle arrangement and the arrangement form of the nozzles are appropriately designed according to the recording resolution and the drawable width.

  In addition, in forming a line head, a plurality of short head modules in which a plurality of nozzles are arranged in a two-dimensional manner are joined together to form a line head having a nozzle row of a required length in the medium width direction. It is possible.

  As shown in FIG. 22, an inkjet printing apparatus using a recording head (212C, 212M, 212Y, 212K) as a line head having a nozzle array having a length corresponding to the full width of the image forming area of the printing medium 201 is illustrated. The print medium 201 is conveyed at a constant speed by the medium conveyance means, and droplets are ejected from the respective recording heads (212 C, 212 M, 212 Y, 212 K) at appropriate timing in accordance with the conveyance of the print medium 201. The image forming area of the print medium 201 can be obtained by performing an operation of moving the print medium 201 relative to each recording head (212C, 212M, 212Y, 212K) once in the transport direction (that is, in one sub-scan). Images can be recorded on

  According to the configuration shown in FIG. 22, the print medium 201 is conveyed at a constant speed in the medium conveyance direction by the medium conveyance means (not shown), and each recording head (212C, 212M, 212Y, 212K) at an appropriate timing. By performing droplet deposition from the nozzles (218C, 218M, 218Y, and 218K), the single dot patterns 202C, 202M, 202Y, and 202K shown in FIG. 21 and the first continuous dot patterns 204C, 204M, 204Y, and 204K and , And second continuous dot patterns 206C, 206M, 206Y, and 206K.

  That is, by performing droplet deposition from each nozzle 218C of the cyan recording head 212C, the single dot pattern 202C, the first continuous dot pattern 204C, and the second continuous dot pattern 206C of FIG. 21 can be formed. . The first continuous dot pattern 204C and the second continuous dot pattern 206C have different inter-dot distances between two overlapping dots. That is, between the first continuous dot pattern 204C and the second continuous dot pattern 206C, the interval between two droplet deposition timings at which two overlapping dots are recorded differs.

  The same applies to each color of M, Y, and K, and the printing medium 201 is transported, and droplet ejection is performed from each nozzle 218M of the magenta recording head 212M of FIG. The dot pattern 202M, the first continuous dot pattern 204M, and the second continuous dot pattern 206M can be formed.

  In addition, the printing medium 201 is transported, and droplets are ejected from the nozzles 218Y of the yellow recording head 212Y of FIG. 22 at appropriate timing, whereby the single dot pattern 202Y of FIG. 21 and the first continuous dot pattern 204Y. And the second continuous dot pattern 206Y can be formed.

  Similarly, by transporting the printing medium 201 and performing droplet deposition from the nozzles 218K of the black recording head 212K of FIG. 22 at an appropriate timing, the single dot pattern 202K of FIG. 21 and the first continuous dot pattern 204K and a second continuous dot pattern 206K can be formed.

  Note that, in FIG. 22, it is necessary to separate the droplet deposition timings of the horizontally adjacent nozzles by a predetermined time (by providing a time difference) so that adjacent dots do not overlap in the horizontal direction (main scanning direction) in FIG. There is. The "laterally adjacent nozzles" referred to herein are adjacent nozzles in the projected nozzle row as a "substantial nozzle row" arranged in the lateral direction.

  In the case of the configuration shown in FIG. 22, the droplets are deposited in the order of K → Y → M → C in accordance with the conveyance of the print medium 201, and for each color, the first of four rows in the two-dimensional nozzle array. By performing droplet deposition in the order of the second row, the third row, and the fourth row, a pattern as shown in FIG. 21 can be formed. However, in order to prevent the dots printed by different nozzles from overlapping each other, it is necessary to separate the droplet deposition timing of the nozzles of each color by a predetermined amount (by providing a time difference).

  The control of the droplet deposition timing as described above is realized by the combination of the characteristic parameter acquisition chart generation unit 62 (see FIGS. 3 and 19) and the print control device 22 (see FIG. 2) described above. Instead of the configuration described with reference to FIGS. 5 and 6, the configuration described with reference to FIGS. 21 and 22 can be employed.

<Inclusion of system characteristic parameters by the concept of system error>
In the above description, "system error" in the terms "no system error" or "system error tolerance" is an error that changes mainly with time and / or from place to place as a fluctuation component of the characteristic parameter. I have explained it with meaning.

  On the other hand, the system error includes, as already described, repeatable errors such as non-ejection due to nozzle failure and errors in nozzle position due to manufacturing errors. These repeatable errors can be understood as parameters indicating the characteristics of the system, and can be considered as parameters of "system error". That is, among system errors, those which can be defined definitively by measurement based on reading results of a test chart or the like, input from a user, or the like, that is, reproducible errors can be considered as characteristic parameters of the system. This repeatable error is referred to herein as a "characteristic error." The characteristic error represents the meaning of an error as a system characteristic. Among the system errors, a characteristic error that is a reproducible error is a characteristic parameter of the system. Therefore, with respect to the characteristic error, it is possible to generate an optimum halftone processing rule in consideration of the characteristic error.

  On the other hand, system errors that change with time and / or location, that is, errors that fluctuate randomly are referred to herein as "random system errors." For random system errors, it is only possible to do a halftone design that gives tolerance to errors.

  The relationship between the characteristic error and the random system error is a representative value such as an expected value (average value) or median value of the distribution of measured values of a certain error item to be noted, and a dispersion or variation range from the representative value. It can be understood that it corresponds to the relationship of

  A further specific example of system error will be described. Examples of the “system error” common to the serial scan type inkjet printing system and the single pass type inkjet printing system include head nozzle error, non-ejection, positional deviation for each droplet type, and the like.

  The nozzle error includes an error in the flying direction of droplets of each nozzle, an error in ejection speed, an error in droplet volume, or an error in dot shape. The ejection velocity may be expressed by the term "droplet velocity". The drop amount error can be grasped as a dot density error. Dot shape is synonymous with "dot profile". In addition, since the error in the flight direction, the error in the ejection velocity, the error in the drop volume, and the error in the dot shape may be errors depending on the droplet type, these errors may be grasped for each droplet type. preferable.

  The nozzle error is expressed by including the error of the nozzle position in the main scanning direction and / or the sub scanning direction, the error of the dot density, the error of the dot diameter, the error of the dot shape, or the error of an appropriate combination thereof. Term.

  The droplet type is the type of droplet corresponding to the dot size that can be print-controlled by the head. For example, in the case of a configuration capable of controlling the discharge of small, medium, and large droplets corresponding to three types of dot sizes, small dots, medium dots, and large dots, three types of droplet species are to be mentioned. The positional deviation for each droplet type means the landing position error in the main scanning direction and / or the sub scanning direction for each droplet type.

  The nozzle error of each nozzle can define a value that can be treated as a “characteristic error” that is generally observed on a per-nozzle basis, while the “random system error” varies with time and / or location. Can be the subject of

  Examples of “system error” in a serial scan type inkjet printing system include bi-directional positional deviation of scanning, bi-directional positional deviation for each droplet type, head vibration error accompanying carriage movement, or paper conveyance error .

  The two-way positional deviation is an error in the main scanning direction between the dot recording position when droplets are ejected while moving in the forward direction in the reciprocating movement of the carriage and the dot recording position when the droplets are ejected while moving in the backward direction. .

  The two-way positional deviation for each droplet type is an error in the position in the main scanning direction and the sub-scanning direction for each droplet type when droplets are ejected while moving in the forward direction and the backward direction of the carriage movement.

  The head vibration error is observed as a fluctuation in dot position in the main scanning direction and / or the sub-scanning direction due to the vibration of the drive belt of the carriage. The sheet conveyance error is an error of the sheet feed amount in the sub-scanning direction which is the sheet conveyance direction. The sheet conveyance error is observed as a recording position error in the sub-scanning direction.

  As an example of “system error” in a single pass type inkjet printing system, an error due to vibration of a head module constituting a line head (referred to as “head module vibration error”) or an error of the mounting position of each head module (Head module mounting error) etc. The head module vibration error is observed as a dot position error in the main scanning direction and / or the sub scanning direction. The head module mounting error can also be observed as a dot position error in the main scanning direction and / or the sub scanning direction.

  The head module mounting error corresponds to the characteristic error.

[About chart for obtaining system error parameters]
In FIG. 5, the “characteristic parameter acquisition chart” for acquiring the characteristic parameter has been described. As described above, the characteristic parameter can be understood as a parameter indicating the characteristic error of the system error, so the characteristic parameter can be understood as a kind of the system error parameter. Therefore, it is understood that the “characteristic parameter acquisition chart” corresponds to one form of the “system error parameter acquisition chart”.

  The following chart can be used as a chart for system error parameter acquisition in a serial scan type inkjet printing system.

  (Example 1) Among the system errors, the chart for acquiring characteristic parameters described in FIG. 5 can be used as a chart for obtaining each nozzle error, undischarge parameter and the like.

  (Example 2) In order to grasp the nozzle error for each droplet type, such as positional deviation for each droplet type (including positional deviation in both directions), the characteristic parameter acquisition chart described in FIG. Create for each of the outbound and inbound routes. For example, in the case of a system capable of controlling droplet deposition of three types of droplets, small droplets, middle droplets, and large droplets, the chart for acquiring characteristic parameters described in FIG. 5 for each droplet type of droplets, middle droplets, and large droplets. Output and measure. With respect to each droplet type, it is possible to obtain positional deviation information indicating how much the positions of dots actually recorded are deviated from the target recording position (the position of the pixel). Further, the characteristic parameter acquisition chart described in FIG. 5 is created for each of the droplet types for each of the forward pass and the return pass. From the measurement results of the respective charts, it is possible to acquire information on positional deviation in the carriage movement direction (main scanning direction) of each of the forward pass and return pass for each droplet type.

  (Example 3) FIG. 23 shows an example of a chart for measuring a head vibration error accompanying carriage movement. Here, only the black recording head 112 K is schematically shown for simplification of the drawing. As shown in FIG. 23, a chart for measuring a head vibration error is created by performing discharge continuously with a specific nozzle 118S of the recording head while moving the carriage. "Continuously discharging" as used herein means that discharging is repeated in a cycle having a time interval to such an extent that each dot does not overlap but is recorded as an independent (isolated) individual dot. .

  In FIG. 23, for convenience of explanation, the dot interval in the main scanning direction and the head vibration error are drawn with extreme emphasis (deformation). The displacement of the head in the main scanning direction and / or the sub-scanning direction fluctuates due to the vibration of the head along with the movement of the carriage.

  The output result of the chart as shown in FIG. 23 is read by the image reading device 26 (see FIG. 1) such as an in-line sensor, and the main scanning direction and the sub scanning direction with respect to the ideal position for each dot. Measure the amount of deviation of each of. It measures how much the actual landing position deviates with respect to each pixel position. The ideal position to be originally hit is determined in one row in the main scanning direction. The position of the pixel to be originally struck in the main scanning direction is represented by "n", and the amount of deviation Δx (n) in the main scanning direction and the amount of deviation Δy (n) in the subscanning direction with respect to each pixel position n can be measured See 24). “N” indicates the position coordinate (X coordinate) in the main scanning direction of the pixel on which the ejection has been performed. n can be an integer from 0 to N. N in this case indicates an integer corresponding to the number of dots to be ejected. Δx (n) and Δy (n) represent the deviation from the ideal landing position.

  25A and 25B show an example of the head vibration error. In FIG. 25A, the horizontal axis represents the pixel position n in the main scanning direction, and the vertical axis represents the amount of positional deviation in the main scanning direction. In FIG. 25B, the horizontal axis represents the pixel position n in the main scanning direction, and the vertical axis represents the positional deviation amount in the sub scanning direction.

  Thus, the shift amount Δx (n) in the main scanning direction and the shift amount Δy (n) in the sub-scanning direction are obtained as a function of the pixel position n.

  Although FIG. 23 illustrates an example in which droplets are continuously ejected from a specific single nozzle 118S, continuous droplets are similarly ejected from a plurality of specific nozzles and obtained from respective measurements. The parameters of the head vibration error may be generated by statistically processing the amount of displacement .DELTA.x (n), .DELTA.y (n).

  (Example 4) The sheet conveyance error is an error that indicates the variation of the sheet feed amount. The sheet conveyance error is an error in which the position of the dot is shifted due to the sheet conveyance mechanism in the printing system. FIG. 26 is an example of a chart for obtaining information on sheet conveyance error. Here, only the black recording head 112 K is schematically shown for simplification of the drawing. In the case of acquiring the parameter of the sheet conveyance error, as in the example of FIG. 23, the droplet deposition is continuously performed by the specific nozzle 118S of the recording head, and the line of the dot row is drawn along the main scanning direction. Note that the specific nozzle 118S in FIG. 23 and the specific nozzle 118S in FIG. 26 may be the same nozzle or different nozzles.

As shown in FIG. 26, when the dot row DL1 of the first line is drawn, the sheet is conveyed by a fixed amount in the sub-scanning direction. "Paper transport" is synonymous with "paper feed" and "paper feed". Let a control amount of sheet conveyance of a fixed amount be Δy ₀ . Then, similarly, the dot row DL2 of the second line is drawn. The sheet transport of such a fixed amount Δy ₀ and the continuous droplet deposition are repeated to draw a plurality of dot rows DL1, DL2, DL3,. It is preferable that this chart be recorded by either the forward pass of carriage movement or only the return pass.

The pixel position as the discharge command position of each dot in the kth dot row is represented as (n, k). k is an integer of 1 to m, and m is an integer of 2 or more. Average value yav (k) of the subscanning direction position of each dot in the kth dot row and average value yav (k + 1) of the subscanning direction position of each dot in the (k + 1) th dot row And the difference of the two, yav (k + 1) -yav (k), is measured as the k-th sheet feeding amount .DELTA.yk. Error of the k-th sheet conveyance can be represented by Δyk-Δy _0.

  FIG. 27 shows an example of the distribution of measured values of Δyk (k = 1, 2... M−1) measured from the chart for measuring the sheet conveyance error. The horizontal axis indicates the sheet conveyance error Δy. The illustrated distribution of the paper feed amount is a distribution according to the normal distribution.

  The following chart can be used as a system error parameter acquisition chart in the single-pass inkjet printing system.

  (Example 5) Among the system errors, the chart for acquiring characteristic parameters described with reference to FIG. 21 can be used as a chart for obtaining each nozzle error, undischarge parameter and the like.

  (Example 6) In order to grasp the nozzle error for each droplet type, such as positional displacement for each droplet type (including positional displacement in both directions), the chart for characteristic parameter acquisition described in FIG. 21 is prepared for each droplet type. Do. For example, in the case of a system capable of controlling droplet deposition of three types of droplets, small droplets, middle droplets, and large droplets, the chart for acquiring characteristic parameters described in FIG. 5 for each droplet type of droplets, middle droplets, and large droplets. Output and measure. With respect to each droplet type, it is possible to obtain positional deviation information indicating how much the positions of dots actually recorded are deviated from the target recording position (the position of the pixel).

  (Example 7) FIG. 28 shows an example of a chart for acquiring a head vibration error parameter in the single pass method. In FIG. 28, for convenience of illustration, only the cyan recording head 212C is shown. The cyan recording head 212C of FIG. 28 is a line head configured by connecting a plurality of head modules 220-j (j = 1, 2,..., Nm). Although the example of Nm = 5 is shown as an example of the number of connection of a head module in the same figure, the number of connection is not specifically limited, It can design to arbitrary number.

  A plurality of head modules 220-j (j = 1, 2,..., Nm) are fixed to a common support frame 222, and form one head bar as a whole. The recording position of the dot fluctuates due to the vibration of the head bar itself. As shown in FIG. 28, while the print medium 201 is conveyed at a constant speed in the sub scanning direction, discharge is continuously performed from a specific single nozzle 228S, and dot rows aligned in the sub scanning direction are recorded. As in the example described in FIG. 23, “continuously discharging” refers to a cycle in which the time interval is set to such an extent that each dot does not overlap and is recorded as an independent (isolated) individual dot. It means to repeat the discharge.

  Similarly to FIG. 23, FIG. 28 is drawn with the dot interval in the sub-scanning direction and the head vibration error extremely emphasized (deformed) for the convenience of description. The displacement of the main scanning direction and / or the sub scanning direction fluctuates due to the vibration of the head bar.

  The output result of the chart as shown in FIG. 28 is read by the image reading device 26 (see FIG. 1) such as an in-line sensor, and the main scanning direction and the sub scanning direction with respect to the ideal position to be originally hit for each dot. Measure the amount of deviation of each of. It measures how much the actual landing position deviates with respect to each pixel position. The ideal position to be originally hit is determined in one row in the sub scanning direction. The position of the pixel to be originally struck in the sub scanning direction is represented by "n", and the deviation amount Δx (n) in the main scanning direction and the deviation amount Δy (n) in the sub scanning direction with respect to each pixel position n can be measured. Here, “n” indicates the position coordinate (Y coordinate) in the sub-scanning direction of the pixel on which the ejection has been performed.

  As in the example described with reference to FIG. 23, from the measurement results of the chart of FIG. 28, parameters of the head vibration error in the single pass system can be obtained.

  (Example 8) As a system error peculiar to the single pass system, there is a head module mounting error. FIG. 29 is an example of a chart for acquiring a parameter of a head module attachment error. Each head module 220-j (j = 1, 2... Nm) may be mounted at a position shifted from a designed mounting position (ideal mounting position). The mounting position of each head module 220-j (j = 1, 2... Nm) can include main scanning direction error, sub scanning direction error, and in-plane rotational direction error. Due to the head module mounting error, the dot recording position deviates from the ideal position.

  In the chart shown in FIG. 29, a row of pixels aligned in the main scanning direction is deposited by the nozzle groups of the head modules 220-j (j = 1, 2,... Nm), and the head modules 220-j A dot row Ds (j) of (j = 1, 2... Nm) units is recorded.

  Then, from the density image of the dot array Ds (j) for each head module 220-j (j = 1, 2... Nm) from the read image of the chart, the block of the dot array Ds (j) is The barycentric position G (j) and the inclination angle θ (j) with respect to the main scanning direction are calculated (see FIGS. 30A and 30B).

In each dot row Ds (j), a gravity center position G ₀ (j) to be originally aimed (that is, ideal in design) is determined. Therefore, as shown in FIG. 30A, the barycentric position G (j) of the dot row Ds (j) calculated from the reading of the chart is from the ideal barycentric position G ₀ (j) to the main scanning direction, It is possible to grasp the deviation of the center-of-gravity position as to how much it deviates in each direction of the sub scanning direction. The main scanning direction error and the sub scanning direction error can be grasped from the deviation of the gravity center position. In addition, since head modules 220-j (j = 1, 2... Nm) are also assumed to be attached in rotation in the plane, as shown in FIG. The inclination angle θ (j) of the dot row Ds (j) with respect to the direction is also measured. The inclination angle θ (j) indicates an error in the in-plane rotational direction.

[About accumulation and utilization of system error parameters]
The “head module attachment error” exemplified above does not change with time, and corresponds to the characteristic error that is determined by the attachment of the head module. On the other hand, each error such as each nozzle error (including each nozzle error for each droplet type), bidirectional positional deviation (including bidirectional displacement for each droplet type), head vibration error, and sheet conveyance error Items can change over time.

  Therefore, the acquisition result of the system error parameter obtained from each chart described above is accumulated in the memory or other storage unit, and the accumulated data of the system error parameter acquired in the past and the newly acquired system error parameter In addition, it is also a preferable form to update distribution data of system errors, determine “random system errors” based on the updated latest system error distribution, and perform tolerance design to system errors.

  Also for the characteristic error included in the system error, the value of “characteristic error” may be updated from the distribution of data including accumulated data of system error parameters acquired in the past and newly acquired system error parameters. preferable.

[Generation of simulation image and evaluation of image quality in system error tolerance design]
When system errors are classified in terms of characteristic errors and random system errors, generation of simulation processing and evaluation of image quality in the case of designing tolerance against system errors in generation of halftone processing rules are levels of multiple random system errors It carries out for every and sets the integrated value (weighted sum) of evaluation by level as an image quality evaluation value.

  When generating a simulation image, “multiple levels” of the random system error to be added are configured according to the system error distribution in the printing system.

  FIG. 31 is a graph showing the relationship between the system error distribution and the level of random system error reflected in generation of a simulation image.

  The horizontal axis in FIG. 31 is a system error. Specific items of the system error may be each nozzle error, bidirectional positional deviation, head vibration error, or sheet conveyance error.

  As shown in FIG. 31, the system errors are distributed in the plus direction and the minus direction with the characteristic error value A as the center. Within such a spread of the system error distribution, a plurality of levels of random system error are defined. In the example shown in FIG. 31, four standard levels of ± σ and ± 2σ are defined using the standard deviation σ of the system error distribution. The value A of the characteristic error corresponds to the average value in the system error distribution. Not limited to a configuration in which the standard deviation σ is used to define the level, the level can be defined by any numerical value.

  When four levels of levels “-2σ”, “-σ”, “+ σ” and “+ 2σ” are defined as error amounts to be added as random system errors when generating a simulation image, By adding a level error amount, a simulation image for each level is generated, and the image quality is evaluated for each simulation image.

  Further, the image quality evaluation value as a total value is calculated from the evaluation of the simulation image performed for each level. In this case, the frequency of giving each random system error at a plurality of levels may be in accordance with the distribution shown in FIG. If “frequency” follows the system error distribution, it means that more simulation images are generated around the central value of the distribution to calculate each evaluation value.

  Alternatively, the weighted sum may be calculated by multiplying the simulation image of the random system error at each level or their evaluation value by the weighting factor according to the distribution shown in FIG.

  For example, as shown in FIG. 32, four levels of levels “+ a1”, “+ a2”, “−a1” and “−a2” are defined as multiple levels of random system errors from the system error distribution. Explain the case. Here, a1 and a2 are numerical values that satisfy “0 <a1 <a2”. In order to simplify the explanation, it is assumed that the central value (average value) of the system error distribution is “0” and the distribution function f (x) is a normal distribution, and levels are set to be symmetrical in the positive and negative directions.

In this case, if the evaluation values of the simulation images to which the random system error of each level is added are represented as Val [+ a1], Val [+ a2], Val [-a1] and Val [-a2], respectively, The image quality evaluation value Total_Value as a comprehensive evaluation value, which is a comprehensive value of the evaluation of the simulation image to which the system error is added, is expressed by the following equation.

Total_Value = A1 * Val [+ a1] + A2 * Val [+ a2] + A3 * Val [-a1] + A4 * Val [-a2] Formula (5)
The weighting factors A1, A2, A3 and A4 follow the system error distribution of FIG. That is, when the distribution function of the system error distribution is represented by f (x), f (-a1) = f (a1) and f (-a2) = f (a2), and a positive proportional constant u is used. A1 = A3 = u × f (a1) and A2 = A4 = u × f (a2).

  In FIG. 32, in order to simplify the explanation, it is assumed that the central value (average value) of the system error distribution is “0” and that the distribution function f (x) is normal distribution, and four levels are set in positive and negative symmetry. Although an example has been described, the distribution function can be determined based on actual chart measurements, and multiple levels can be arbitrarily set within the range of distribution spread.

[Apply to formula for calculating image quality evaluation value]
The equations (1) to (4) for image quality evaluation described above are as follows when reconsidered from the viewpoint of the characteristic error and the random system error as the fluctuation component. That is, the description of the granularity evaluation value [no system error] described in the equations (1) to (4) can be understood by replacing it with the granularity evaluation value [no random system error (there is a characteristic error)]. The description of the evaluation value [system error present] can be understood as the granularity evaluation value [random system error present]. Further, the description of the streak evaluation value [with system error] can be understood as the streak evaluation value [with random system error]. Hereinafter, with respect to each of the equations (1) to (4), the modified equations are described by introducing the concept described in FIG. 32 and the equation (5).

[1] In the case of the dither method The following equation (6) can be used as a correction equation of the equation (1) in the case of the dither method.

Image quality evaluation value = granularity evaluation value [without random system error (with characteristic error)] + α × {A1 × (granularity evaluation value [with system error (+ a1)) + granularity evaluation value [with system error (−a1) ))) + A 2 × (granularity evaluation value [system error (+ a 2)) + granularness evaluation value [system error (-a 2)]) + ...}
+ Β × {A1 × (Strain evaluation value [system error (+ a1)) + streak evaluation value [system error (-a1)] + A2 × (Strain evaluation value [system error (+ a2))] + streak Evaluation value [with system error (-a2)]) + ...}
... Equation (6)
Note that a1, a2, A1, and A2 follow the relationship described in FIG. It can replace with Formula (1) and can evaluate using Formula (6).

[2] In the case of the error diffusion method The error diffusion method is also the same as the above-described dither method, and the following equation (7) is used as a correction equation of equation (2) in the case of the error diffusion method already described. Can be used.

Granularity evaluation value [with system error]
= Α × {A 1 × {granularity evaluation value [system error (with first error "+ a 1" error added)] + granularity evaluation value [system error with (second group "+ a 1" error added] + ... + Granularity evaluation value [with system error (“-a1” error added to the first group ”) + Granularity evaluation value [system error with (“ −a1 ”error added to the second group)” + ...}
+ A 2 × {granularity evaluation value [with system error (“+ a 2” error added to first group)] +
Granularity evaluation value [with system error (“+ a2” error added to second group ”) + ...
+ Granularity evaluation value [with system error (“-a2” error added to first group ”)] + Granularity evaluation value [system error (with“ -a2 ”error added to second group)] +. .}
+ Β × {A1 × {Strain evaluation value [with system error (“+ a1” error added to first group ”)] +
Evaluation value of streak [with system error (“+ a1” error added to the second group)] + ...
+ Streak evaluation value [with system error (“-a1” error added to first group)] + streak evaluation value [system error with (“−a1” error added to second group ”) + ...}
+ A2 × {Strain evaluation value [with system error ("+ a2" error added to the first group) "+
Evaluation value of streak [with system error (“+ a2” error added to the second group ”) + ...
+ Streak evaluation value [with system error (“-a2” error added to the first group) ”+ streak evaluation value [system error with (“ −a2 ”error added to the second group)” + ...} + ...} ... Equation (7)
It can replace with Formula (2) and can evaluate using Formula (7).

[3] When the void and cluster method is used for the dither method The following equation (8) can be used as a correction equation of the equation (3) in the case of the void and cluster method.
Image evaluation value = energy [no random error (characteristic error)]
+ Α × {A1 × (energy [system error (+ a1)) + energy [system error (-a1)] + A2 × (energy [system error (+ a2)) + energy [system error (-a2)] ) + ....}
+ Β × {A1 × (Strain energy [system error (+ a1)) + streak energy [system error (-a1)] + A2 × (Strain energy [system error (+ a2)) + streak energy [system error Yes (-a2)]) + ...} ... Formula (8)
It can replace with Formula (3) and can evaluate using Formula (8).

[4] In the case of the DBS method Also in the case of the DBS method, an evaluation method similar to the example described in the above equations (6) to (8) can be adopted when evaluating the simulation image.

[5] Case of Evaluation Formula in Automatic Selection of Halftone Processing One halftone processing rule out of two or more types of halftone processing rules has been described as being used for evaluation of image quality when the system automatically selects one. The following equation (9) can be used as a correction equation of equation (4).

Image quality evaluation value = p × granularity evaluation value [no random system error (with characteristic error)] + q × {A1 × {granularity evaluation value [with system error (“+ a1 error added to first group”)] + Granularity evaluation value [system error (with error of "+ a1" added to the second group) + ... + granularity evaluation value [system error with ("-a1" error added to the first group) "+ granularity evaluation Value [with system error (error of “−a1” added to the second group) ”+ ...}
+ A 2 × {granularity evaluation value [with system error (“+ a 2” error added to first group)] + Granularity evaluation value [system error (“+ a 2” error added to second group)] + ... + Granularity evaluation value [with system error (error of "-a2" added to first group)]
+ Granularity evaluation value [with system error (error of “−a2” added to the second group) ”+ ...} +.
+ R × {A 1 × {Strain evaluation value [with system error (error added to the first group "+ a 1")] + Stripe evaluation value [system error with the error ("+ a 1 error added to the second group)" + Streak evaluation value [with system error (error of “-a1 added to first group)] + streak evaluation value [with system error (error of“ −a1 ”added to second group)] + ...} +
A2 x {Strain evaluation value [system error (with error of + a2 added to first group)] + streak evaluation value [with system error (with error of + a2)} + ... + streak evaluation Value [with system error (error of “-a2 added to first group)] + streak evaluation value [system error (with error of“ -a2 ”added to second group)] + ...} +.
... Formula (9)
Here, in order to simplify the description, the case where one-dimensional distribution is assumed as the system error distribution as shown in FIG. 31 and FIG. 32 and the calculation formula of the image quality evaluation value is also assumed one-dimensional error. However, in actuality, each nozzle error, head vibration error, and the like show two-dimensional error distributions in the main scanning direction and the sub scanning direction, as shown in FIG. 33 to FIG.

  FIG. 33 is a diagram representing the two-dimensional error distribution in the main scanning direction and the sub scanning direction by shading. FIG. 34 is an error distribution sectional view taken along the main scanning direction in the two-dimensional error distribution shown in FIG. FIG. 35 is an error distribution sectional view taken along the sub scanning direction in the two-dimensional error distribution shown in FIG.

  For example, as shown in FIG. 34 and FIG. 35, as the multiple levels of the random system error from the system error distribution, the levels “+ a1”, “+ a2”, “− When a1 ”,“ -a2 ”and“ + b1 ”,“ + b2 ”,“ -b1 ”, and“ -b2 ”are defined, the image quality evaluation value Total_Value as an example is the following in place of equation (5): It is expressed by equation (10).

Total_Value = A1 × Val [+ a1,0] + A2 × Val [+ a2,0] + A3 × Val [-a1,0] + A4 × Val [-a2,0]
+ B1 x Val [0, + b1] + B2 x Val [0, + b2] + B3 x Val [0,-b1] + B4 x Val [0,-b2]
+ C1 x Val [+ a1, + b1] + C2 x Val [+ a1,-b1] + C3 x Val [-a1, + b1] + C4 x Val [-a1,-b1]
+ D1 x Val [+ a2, + b2] + D2 x Val [+ a2,-b2] + D3 x Val [-a2, + b2] + D4 x Val [-a2,-b2] Formula (10)
Here, an evaluation value of a simulation image obtained by adding a random system error of an error amount of x in the main scanning direction and y in the sub scanning direction is represented as Val [x, y]. The weighting factors A1 to A4, B1 to B4, C1 to C4, and D1 to D4 follow the system error distribution shown in FIGS. That is, if the distribution function of the system error distribution is represented by f (x, y),
A1 = A3 = u × f (a1,0), A2 = A4 = u × f (a2,0), B1 = B3 = u × f (0, b1), B2 = B4 = u × f (0, b2) C1 = C2 = C3 = C4 = u × f (a1, b1), D1 = D2 = D3 = D4 = u × f (a2, b2). Here, u represents a positive proportional constant.

  In the simulation image generation described above and the image quality evaluation represented by the equations (1) to (10), the method for generating a simulation image with a system error and the image quality evaluation is the halftone image. The present embodiment is an embodiment in which a predetermined system error is independently added to each group of pixels belonging to each printing order, pass, and timing to generate a simulation image and calculate an evaluation value. However, image quality evaluation may be performed by generating a simulation image in which a predetermined system error is added to all of the groups of pixels belonging to each printing order, pass, and timing. In addition, each nozzle error (including positional deviation for each droplet type), non-ejection, bidirectional positional deviation (including bidirectional positional deviation for each droplet type), head vibration error, and paper conveyance error described so far The system error of each item such as, may be added to the halftone image independently to generate a simulation image and the image quality may be evaluated, or the system error of all items may be simultaneously added to the halftone image to generate a simulation image The image quality may be evaluated.

  In addition to the above, regarding the method of generating a simulation image with a system error (including setting of an error level) and the image quality evaluation, many embodiments are possible without departing from the spirit of the present invention.

Configuration of Image Processing Apparatus According to Third Embodiment
FIG. 36 is a main block diagram for explaining the function of the image processing apparatus according to the third embodiment. In FIG. 36, elements that are the same as or similar to the configuration described in FIG. 3 are given the same reference numerals, and descriptions thereof will be omitted.

  The image processing apparatus 20 according to the third embodiment shown in FIG. 33 includes a system error parameter acquisition unit 53, a system error parameter storage unit 55, and a system error setting unit 67. The system error parameter acquisition unit 53 is means for acquiring a parameter related to a system error. The system error parameter acquisition unit 53 corresponds to one form of “parameter acquisition means”. The system error parameter acquisition unit 53 plays the same role as the characteristic parameter acquisition unit 52 described with reference to FIG. 3 and has a role as the characteristic parameter acquisition unit 52.

  The system error parameter storage unit 55 is means for storing the system error parameter acquired from the system error parameter acquisition unit 53. The system error parameter storage unit 55 includes a characteristic error storage unit 55A and a random system error storage unit 55B. The characteristic error storage unit 55A is a storage unit that stores parameters of characteristic errors in system errors. The random system error storage unit 55B is a storage unit that stores parameters of the random system error in the system error. The system error parameter storage unit 55 stores data of parameters acquired in the past. The control unit 50 calculates statistical processing from the distribution of the system error data group stored in the system error parameter storage unit 55, and calculates the characteristic error value corresponding to the central value of the system error distribution and the random system error. Define multiple levels.

  The system error parameter storage unit 55 has a role as the characteristic parameter storage unit 54 described with reference to FIG. The system error parameter storage unit 55 corresponds to one form of storage means.

  The system error setting unit 67 is a means for setting parameters relating to a system error assumed when printing is performed by the printing system 10 (see FIG. 1). The system error setting unit 67 sets parameters as simulation conditions for generating a simulation image in the simulation image generation unit 68. The system error setting unit 67 corresponds to one mode of “setting means”. Further, the process of setting the system error by the system error setting unit 67 corresponds to one mode of the “system error setting process”. The function of the system error setting unit 67 may be mounted on the control unit 50.

  The simulation image generation unit 68 reflects the system error indicated by the parameter set by the system error setting unit 67 on the halftone processing result, and generates a simulation image with a higher resolution than the halftone processing result. Alternatively, once a high resolution simulation image is generated, it is smoothed and then converted to a low resolution simulation image. The process of the process of generating a simulation image by the simulation image generation unit 68 corresponds to one mode of the “simulation image generation process”. The evaluation value calculation unit 70 calculates an evaluation value for evaluating the image quality of the simulation image generated by the simulation image generation unit 68. In addition, the evaluation value calculation unit 70 functions as a calculation unit that calculates a weighted sum by multiplying a weighting coefficient to the sum of evaluation values of simulation images for each level or the evaluation value of simulation images for each level.

  In addition, the image processing apparatus 20 can use the input device 34 to directly input characteristic parameters regarding the characteristics of the printing system 10 by the user. That is, the aspect of the characteristic parameter acquisition unit 52 in the image processing apparatus 20 may be configured such that the user directly inputs the characteristic parameter related to the characteristic of the printing system 10 using the input device 34. The characteristic parameter may be automatically acquired from the measurement result of the chart (chart for system error parameter acquisition), or a combination of these may be used. The input device 34 corresponds to one form of "information input means". The image processing apparatus 20 described with reference to FIGS. 3 and 19 can also be configured to be able to directly input parameters from the input device 34.

  The image processing apparatus 20 illustrated in FIG. 36 is configured to be able to perform generation and evaluation of simulation images described in Expressions (6) to (9).

  The contents of processing by the image processing apparatus 20 in each embodiment described above can be grasped as an image processing method.

[Description of characteristic parameter update according to the fourth embodiment]
Next, characteristic parameter updating according to the fourth embodiment will be described.

<Overall configuration>
FIG. 37 is a block diagram showing the configuration of a printing system according to the fourth embodiment. In FIG. 37, the same components as in FIG. 3 are assigned the same reference numerals and descriptions thereof will be omitted as appropriate.

  The characteristic parameter update according to the fourth embodiment described below is a specification in which a difference between an existing characteristic parameter which is a characteristic parameter acquired in the past and a newly acquired new characteristic parameter is acquired in advance. The characteristic parameter is updated when the value is exceeded.

  That is, in the image processing apparatus 20A shown in FIG. 37, a characteristic parameter update determination unit 230 and a specified value acquisition unit 232 are added to the image processing apparatus 20 shown in FIG.

  The characteristic parameter update determination unit 230 functions as a characteristic parameter update determination unit that determines whether to update the characteristic parameter. The determination as to whether or not to update the characteristic parameter is performed based on the defined value acquired by the defined value acquiring unit 232.

  The specified value acquisition unit 232 functions as a specified value acquisition unit that acquires a specified value used to determine whether to update the characteristic parameter in the characteristic parameter update determination unit 230.

  As an example of the acquisition mode of the prescribed value, an aspect in which the prescribed value is calculated by the prescribed value calculation unit (not shown) functioning as the prescribed value calculation means, a prescribed value table (not shown) functioning as the prescribed value storage means There is a mode of referring to a specified value table in which specified values acquired and stored in are stored, a mode of obtaining a specified (specified) value input using the input device 34, and the like.

  The characteristic parameters stored in the characteristic parameter storage unit 54 shown in FIG. 37 can be applied as the existing characteristic parameters. The existing characteristic parameter may apply the characteristic parameter acquired at the end among the characteristic parameters acquired in the past, or is a representative value of the characteristic parameter acquired in the past, such as an average value of the characteristic parameters acquired in the past It may be

  The difference between the existing characteristic parameter and the new characteristic parameter is the difference between the existing characteristic parameter and the new characteristic parameter calculated by subtracting the existing characteristic parameter from the new characteristic parameter, or the existing characteristic parameter and the new characteristic parameter The absolute value of the difference with the characteristic parameter of can be applied.

  The difference between the existing characteristic parameter and the new characteristic parameter may apply the ratio of the new characteristic parameter to the existing characteristic parameter calculated by dividing the new characteristic parameter by the existing characteristic parameter.

  The specified value may be constant (fixed value) or may be changed each time the characteristic parameter is acquired. That is, the prescribed value acquiring unit 232 may acquire the fixed value once as the prescribed value or may acquire the prescribed value multiple times.

  In the aspect of updating the prescribed value, it is preferable to hold (store) the past prescribed value (history of the prescribed value). If the history of the specified value is not held, the specified value may be stored inside the printing system, or the user may specify (input) the specified value. In the mode in which the user designates the prescribed value, the printing system is equipped with a prescribed value designation unit (prescribed value input unit). The specified value designation unit (specified value input unit) can apply the input device 34.

<Description of Method of Generating Halftone Processing Rule to Which Characteristic Parameter Update According to Fourth Embodiment is Applied>
FIG. 38 is a flowchart of a method of generating halftone processing rules to which characteristic parameter updating is applied according to the fourth embodiment. The chart output process S100 for acquiring characteristic parameters, the image reading process S101, and the acquisition process S102 for characteristic parameters shown in FIG. 38 are the chart output process S10 for acquiring characteristic parameters and the process S11 for reading image, and the acquisition of characteristic parameters shown in FIG. It is the same as step S12, and the description here is omitted.

  The specified value acquiring step S103 shown in FIG. 38 acquires a specified value. The specified value acquiring step S103 is performed by the specified value acquiring unit 232 shown in FIG. As one aspect of the specified value acquiring process, the specified value calculating process for calculating the specified value, the specified value table referring process for referring to the table in which the specified value is stored, or the specified value input process for acquiring the input specified value There is a specified value acquiring step of acquiring the input specified value.

  When the defined value is acquired by the defined value acquiring step S103 shown in FIG. 38, the process proceeds to the characteristic parameter update determining step S104.

  In the characteristic parameter update determination step S104, it is determined whether to update the characteristic parameter based on whether the difference between the existing characteristic parameter and the new characteristic parameter acquired in the characteristic parameter acquisition step S102 exceeds a specified value. Do.

  If the difference between the existing characteristic parameter and the new characteristic parameter acquired in the characteristic parameter acquisition process S102, which is No in the characteristic parameter update judgment process S104, is less than or equal to the specified value, the process proceeds to the end process.

  On the other hand, when the difference between the existing characteristic parameter and the new characteristic parameter, which is determined as Yes in the characteristic parameter update determination step S104, exceeds the specified value, the process proceeds to the characteristic parameter update step S105.

  The characteristic parameter updating step S105 updates the characteristic parameters applied to halftone processing rule generation. That is, the existing characteristic parameter is updated to a new characteristic parameter, and the process proceeds to halftone processing rule generation step S106.

  The halftoning rule generation step S106 generates two or more types of halftoning rules having different priorities of items required for halftoning using the characteristic parameters updated by the characteristic parameter updating step S105.

  The halftone selection chart output step S107 and the halftone selection operation step S108 have the same contents as the halftone selection chart output step S16 and the halftone selection operation step S18 shown in FIG. 4, and the description thereof is omitted here. Do.

  The characteristic parameter may be updated when starting any print job, or while any print job is being executed (eg, once every 100 sheets, once every 1000 sheets, etc.) It may be done, or may be done at the time of input by the user (e.g., when the user regards the image quality as a problem). In addition, the characteristic parameter may be updated when the printing system (apparatus) is started.

<Description of update of characteristic parameter when system error is applied to specified value>
FIG. 39 is an explanatory diagram of an example of the update of the characteristic parameter when the system error is applied to the specified value. The image processing apparatus 20A shown in FIG. 37 may determine the prescribed value based on the random characteristic error. That is, the predetermined value acquiring unit 232 shown in FIG. 37 and the predetermined value acquiring step S103 shown in FIG. 38 calculate the predetermined value determined based on the random system error which is an error which changes irregularly as the characteristic of the printing system. It can be configured to acquire.

  ± σ and ± 2σ shown in FIG. 39 are examples of specified values determined based on random system errors centered on the characteristic error A. σ is a standard deviation of random system error, and ± σ, ± 2σ, or ± σ × α can be determined as a prescribed value to determine whether to change the characteristic parameter. Here, α is any positive real number except 0. For example, when the specified value is ± 2σ and the difference between the existing characteristic parameter and the new characteristic parameter is B shown in FIG. 39, the difference B between the existing characteristic parameter and the new characteristic parameter is the specified value Since 2σ is exceeded, the characteristic parameters are updated.

  In the case where the random system error fluctuates due to the acquisition (update) of the characteristic parameter being performed multiple times, it is preferable to update the specified value according to the fluctuation of the random system error.

  The update of the characteristic parameter may update the existing characteristic parameter to a new characteristic parameter, or may update the existing characteristic parameter to an average value of the existing parameter and the new characteristic parameter. The characteristic parameter may be updated to a value calculated using the latest existing characteristic parameter among the existing characteristic parameters, or the existing characteristic parameter and the new characteristic parameter that are predetermined in order of the latest. In this case, it is not necessary to store all of the characteristic parameters acquired in the past, but it is sufficient to store the latest existing characteristic parameters or a predetermined number of existing characteristic parameters in the new order, The storage capacity of the characteristic parameter storage unit 54 (see FIG. 3) that stores the characteristic parameter can be reduced.

  Even if the difference between the existing characteristic parameter and the new characteristic parameter is less than a specified value, that is, even if the characteristic parameter is not updated, the random system error may be changed based on the new characteristic parameter. In addition, the specified value may be changed along with the change of the random system error.

  It is possible to use a characteristic error (indicated by a symbol A in FIG. 39) as the characteristic parameter. That is, when the difference between the characteristic error of the existing characteristic parameter and the error characteristic of the new characteristic parameter exceeds a prescribed value (for example, ± σ or ± 2σ shown in FIG. 39), the characteristic parameter is updated. Aspects are also possible.

<Specific example of characteristic parameter to be updated>
Next, a specific example of the characteristic parameter to be updated will be described. Among the characteristic parameters listed below, those described above will be omitted as appropriate.

  As the characteristic parameter to be updated, the average dot density in the plurality of printing elements, the average dot diameter in the plurality of printing elements, the average dot shape in the plurality of printing elements, and the plurality of printings are characteristic parameters common to the plurality of printing elements There is landing interference in the element.

  The specified value when the characteristic parameter to be updated is the average dot density in the plurality of printing elements, the average dot diameter in the plurality of printing elements, and the average dot shape in the plurality of printing elements may be absolute values or The average dot density in the plurality of printing elements, the average dot diameter in the plurality of existing printing elements, and the ratio to the average dot shape in the plurality of existing printing elements may be used.

  Average dot density, average dot diameter, and average dot shape in a plurality of printing elements are regarded as a characteristic error, and dot density of individual printing elements with respect to average dot density, average dot diameter, and average dot shape in a plurality of printing elements If the tolerance design is performed by regarding the variation in dot diameter, the variation in dot diameter, and the variation in dot shape as a random system error, update the characteristic error or random system error according to the following procedure, or change the characteristic error or random Update system error.

  First, new characteristic parameters (average dot density, average dot diameter, and average dot shape in multiple printing elements) and new random system error (dispersion of dot density of individual printing elements, dot diameter) from new characteristic parameters The variation and the variation of the dot shape are determined. Next, the difference between the existing characteristic error and the new characteristic error is obtained, and it is determined whether the difference between the existing characteristic error and the new characteristic error exceeds a specified value. If the difference between the existing characteristic error and the new characteristic error exceeds the specified value, the characteristic error is updated.

  Furthermore, the difference between the existing random system error and the new random system error is calculated, and it is determined whether the difference between the existing random system error and the new random system error exceeds a specified value, and the existing random system error The random system error is updated if the difference with the new random system error exceeds a specified value.

  The specified value when the characteristic parameter to be updated is landing interference is Old (x), which is the variation of the existing inter-dot distance in the relationship between the inter-dot distance and the variation of the inter-dot distance shown in FIG. The sum of absolute values of New (x) -Old (x) which is the difference from New (x) which is the change amount of the new inter-dot distance, or the sum of squares, the change amount of the existing inter-dot distance and the new Apply an index representing a difference such as the sum of New (x) / Old (x) which is a ratio to the amount of change in distance between dots, or a sum of squares, or an index representing similarity such as a correlation coefficient it can.

The sum of the absolute values of the differences between the amount of change in the existing inter-dot distance and the amount of change in the new inter-dot distance is expressed as x | New (x) −Old (x) |. The sum of squares of differences between the existing amount of change in inter-dot distance and the amount of change in new inter-dot distance is expressed as Σ (New (x) −Old (x)) ² . The sum of the ratio of the change amount of the existing inter-dot distance to the change amount of the new inter-dot distance is expressed as Σ (New (x) / Old (x)). The sum of squares of the ratio of the change amount of the existing inter-dot distance to the change amount of the new inter-dot distance is expressed as Σ (New (x) / Old (x)) ² . AveNew is the average of the variation of the new inter-dot distance, AveOld is the average of the variation of the existing inter-dot distance, and the correlation coefficient is {{(New (x) −AveNew) × (Old (x) − AveOld)} / {Σ (New (x) -AveNew) ² × Σ (Old (x) -AveOld) ² }.

  The relationship between the inter-dot recording time difference and the variation of the inter-dot distance is schematically represented in FIG. 40 with the horizontal axis representing the inter-dot recording time difference instead of the inter-dot distance. The dot-to-dot recording time difference is the impact time difference between any two dots, or the drop time difference between any two dots. The specified value when the characteristic parameter is landing interference is the absolute value of the difference between the change in the existing inter-dot distance and the change in the new inter-dot distance in the relationship between the inter-dot recording time difference and the change in the inter-dot distance. Sum of squares, sum of squares of difference between existing inter-dot distance variation and new inter-dot distance variation, sum of ratio of existing inter-dot distance variation and new inter-dot distance variation An index such as the sum of squares of the ratio of the change amount of the existing inter-dot distance to the change amount of the new inter-dot distance or an index representing the similarity such as the correlation coefficient can be applied.

  As another example of the characteristic parameter to be updated, the dot density for each printing element, the dot diameter for each printing element, the dot shape for each printing element, the dot formation position deviation for each printing element, which are the characteristics of individual printing elements Examples include non-ejection for each printing element, and misalignment of dots for each droplet type per printing element. The dot formation position shift for each printing element corresponds to the printing position error of the dot for each printing element. The non-ejection for each printing element corresponds to an unrecordable abnormality for each printing element.

  The specified value when the dot density for each printing element, the dot diameter for each printing element, and the dot shape for each printing element are characteristic parameters may be absolute values, or the dot density for each existing printing element, existing printing The dot diameter for each element and the ratio to the dot shape for each existing printing element may be used. One predetermined value may be defined for an arbitrary printing element group such as a printing element array or a plurality of printing elements arranged in the vicinity.

  The specified value in the case where the non-ejection for each printing element is the characteristic parameter may be that the characteristic parameter may be updated immediately when a non-ejection printing element occurs, or printing element group The characteristic parameter may be updated if a predetermined number of printing elements out of the plurality of printing elements arranged in the position fail. For example, there is an aspect in which the characteristic parameter is updated when 10% of printing elements fail for one printing element row.

  When the positional deviation of dots for each droplet type for each printing element is used as the characteristic parameter, the characteristic of the positional deviation of dots for each droplet type may be different even with the same printing element. Good.

  As another example of the characteristic parameter to be updated, a characteristic parameter unique to the serial scan method, such as a two-way printing position deviation of scanning, a two-way printing position deviation of scanning for each droplet type, a head vibration error accompanying carriage movement, And paper conveyance errors. The two-way printing position deviation of the scan corresponds to the two-way printing position deviation. The two-way printing position shift of the scan for each drop type corresponds to the two-way printing position shift for each drop type. The head vibration error caused by the carriage movement corresponds to the vibration error of the image forming unit. The sheet conveyance error corresponds to the conveyance error of the print medium.

  The specified value in the case of using the head vibration error accompanying the carriage movement as the characteristic parameter can apply an index that represents the difference between the head vibration error due to the existing carriage movement and the head vibration error due to the new carriage movement. As an index representing the difference between the head vibration error due to the existing carriage movement and the head vibration error due to the new carriage movement, in the shift amount Δx (n) in the main scanning direction with respect to the pixel position n shown in FIG. A sum of absolute values of differences between the existing displacement amount in the main scanning direction and the displacement amount in the new main scanning direction, or the displacement amount in the existing main scanning direction and the displacement amount in the new main scanning direction The sum of the squares of the differences of can be applied. The difference between the existing displacement amount in the main scanning direction and the displacement amount in the new main scanning direction may be calculated by subtracting the existing displacement amount in the main scanning direction from the displacement amount in the new main scanning direction. it can.

  Further, as an index indicating the difference between the head vibration error due to the existing carriage movement and the head vibration error due to the new carriage movement, the amount of deviation Δx (n in the main scanning direction with respect to the pixel position n shown in FIG. The sum of the ratio of the existing main scanning direction displacement amount to the new main scanning direction displacement amount or the ratio between the existing main scanning direction displacement amount and the new main scanning direction displacement amount It can be the sum of squares of. The ratio between the existing displacement amount in the main scanning direction and the displacement amount in the new main scanning direction is calculated by dividing the displacement amount in the new main scanning direction by the displacement amount in the existing main scanning direction. Can.

  Instead of the displacement amount Δx (n) in the main scanning direction with respect to the pixel position n, or in combination with the displacement amount Δx (n) in the main scanning direction with respect to the pixel position n, The shift amount Δy (n) in the scanning direction can be applied.

  As the specified value in the case of using the head vibration error accompanying the carriage movement as the characteristic parameter, an index representing similarity can be applied. Correlation coefficients can be applied as similarities. The specified value in the case where the head vibration error accompanying the carriage movement is used as the characteristic parameter may be determined based on the magnitude of the head vibration error accompanying the carriage movement. The variance or standard deviation of the magnitude of the head vibration error accompanying carriage movement can be applied as the magnitude of head vibration error accompanying carriage movement. The head vibration error accompanying carriage movement corresponds to the head vibration error.

  As another example of the characteristic parameter to be updated, a head module (indicated by reference numeral 220-j (= 1, 2,..., Nm) in FIG. 28) which is a characteristic parameter unique to the single pass system There is an error.

  As the specified value in the case where the head module vibration error in the single pass method is used as the characteristic parameter, an index representing the difference between the existing head module vibration error and the new head module vibration error can be applied. As an index indicating the difference between the existing head module vibration error and the new head module vibration error, the main scanning direction (reference numeral with respect to the position of the paper conveyance direction (sub scanning direction, illustrated with symbol y) shown in FIG. Sum of the absolute value of the difference between the existing positional deviation amount in the main scanning direction and the novel positional deviation amount in the main scanning direction, or the existing value in the positional deviation amount (dot positional deviation amount) with x. The sum of the squares of the difference between the positional deviation amount in the main scanning direction and the positional deviation amount in the new main scanning direction can be calculated.

  The difference between the existing amount of displacement in the main scanning direction and the amount of displacement in the new main scanning direction is calculated by subtracting the amount of displacement in the main scanning direction from the amount of displacement in the main scanning direction. Can.

  In addition, as an index indicating the difference between the existing head module vibration error and the new head module vibration error, the main scanning direction with respect to the position of the sheet conveyance direction (sub scanning direction, symbol y is shown) shown in FIG. The sum of the ratio of the amount of positional deviation in the main scanning direction to the amount of positional deviation in the new main scanning direction, or the existing amount of positional deviation (dot positional deviation amount) (indicated by a symbol x) The sum of squares of the ratio between the amount of positional deviation in the main scanning direction and the amount of positional deviation in the new main scanning direction can be used.

  The ratio between the existing displacement amount in the main scanning direction and the displacement amount in the new main scanning direction is calculated by dividing the displacement amount in the new main scanning direction by the displacement amount in the existing main scanning direction. Can.

  As the specified value in the case of using the head module vibration error in the single pass method as the characteristic parameter, an index representing the similarity between the existing head module vibration error and the new head module vibration error can be applied. The correlation coefficient can be applied as an index that represents the similarity between the existing head module vibration error and the new head module vibration error. The head module vibration error corresponds to the head module vibration error in the head constituted by a plurality of head modules.

  The prescribed value in the case of using the head module vibration error as the characteristic parameter may be determined based on the magnitude of the head module vibration error. As the magnitude of the head module vibration error, the variance or standard deviation of the magnitude of the head module vibration error can be applied.

  In the printing system shown in the present embodiment, at least one of the characteristic parameters listed here may be updated.

<Modified Example of Printing System According to Fourth Embodiment>
FIG. 41 is a flowchart of a method of generating halftone processing rules applied to a modification of the printing system according to the fourth embodiment. In FIG. 41, the same steps as in FIG. 38 are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

  Updating of the characteristic parameters in the method of generating halftone processing rules shown in FIG. 38 can be implemented each time a print job is executed. The update of the characteristic parameters shown in the flowchart of FIG. 38 may be performed during print job execution. However, in the case where the characteristic parameter is updated during print job execution, it is preferable to determine the halftone processing rule so that printing does not stop when the user selects the halftone processing rule.

  The flowchart shown in FIG. 41 replaces the halftone selection chart output step S107 and the halftone selection operation step S108 in the flowchart shown in FIG. 38, and determines a halftone processing rule that determines halftone processing rules based on priority parameters. A determination step S110 is included.

  In the halftone processing rule determination step S110 shown in FIG. 41, after the two or more types of halftone processing rules shown in FIG. 20 are generated, priority is selected from among the generated two or more types of halftone processing rules. The process is the same as the process (step S17) in which one type of halftone processing rule is determined based on the degree parameter, and the description thereof is omitted here.

  That is, in the flowchart shown in FIG. 37, if the user is not selected in the halftone selection operation step S108, there is a concern that the printing may be stopped without determining the halftone processing rule to be applied to the printing. On the other hand, in the flowchart shown in FIG. 41, since the halftone processing rule is determined based on the priority parameter out of the two or more types of halftone processing rules in the halftone processing rule determination step S110, the halftone processing should be applied to printing. Printing does not stop without determining the tone processing rules.

  According to the printing system configured as described above, since the characteristic parameter is updated according to the difference between the existing characteristic parameter and the new characteristic parameter, the characteristic parameter is updated according to the fluctuation of the characteristic of the printing system. be able to.

  By generating the halftoning rule using the updated characteristic parameter, it is possible to print using the halftoning rule corresponding to the variation of the characteristic of the printing system.

[Description of chart output for characteristic parameter acquisition according to the fifth embodiment, and generation of halftone processing rule]
Next, characteristic parameter acquisition chart output and halftone processing rule generation according to the fifth embodiment will be described.

<Flow chart of characteristic parameter acquisition chart output according to the fifth embodiment and halftone processing rule generation method to which halftone processing rule generation is applied>
FIG. 42 is a flowchart of a method of generating halftone processing rules according to the fifth embodiment. The method of generating halftone processing rules whose flowchart is shown in FIG. 42 can be applied to the image processing apparatus 20 shown in FIG. 3 and the image processing apparatus 20A shown in FIG. In the following description, it is assumed that the characteristic parameter acquisition chart output and the halftone processing rule are executed during an arbitrary print job.

  In the method of generating a halftone processing rule whose flowchart is shown in FIG. 42, an image after the image accompanied with the characteristic parameter acquisition chart is outputted based on the characteristic parameter acquisition chart outputted together with the image. Halftoning rules to be used for output are generated. The image after the image to which the characteristic parameter acquisition chart is additionally output may be the next image of a plurality of images sequentially output or may be an image after the next image. The plurality of images may have the same content or different content.

  In the initialization step S120, zero is substituted for iA representing the image number, and zero is substituted for jA representing the halftoning rule number. That is, the first image in a given print job is determined, and the halftone processing rule applied to the first image is determined.

  In the present embodiment, values substituted for the image number iA, the halftone processing rule number jA, and the chart number kA are zero and a positive integer. In the following description, the iA-th image is described as the image iA, the jA-th halftone processing rule is described as the halftone processing rule jA, and the kA-th characteristic parameter acquisition chart is the characteristic parameter acquisition chart kA (chart Write as kA). In FIG. 42, the characteristic parameter acquisition chart kA (chart kA) is not shown.

  In the image output step S122, halftone processing is performed on the image data representing the image iA using the halftone processing rule jA, and the image iA is output. Halftone processing is performed by the halftone processing unit 80 shown in FIG. Image output is performed by the image processing apparatus 20 shown in FIG. The halftone processing unit 80 corresponds to halftone processing means.

  In the determination step S124, it is determined whether all outputs of the image iA have been completed. If all outputs of the image iA have been completed, which is a Yes determination in the determination step S124, the process proceeds to an end step. If all the outputs of the image iA are not completed, which is a No determination in the determination step S124, the process proceeds to a characteristic parameter acquisition chart output step S126.

  The characteristic parameter acquisition chart output step S126 outputs the characteristic parameter acquisition chart along with the image iA. As an aspect of outputting the characteristic parameter acquisition chart accompanying the image iA, there is an aspect of outputting the characteristic parameter acquisition chart to a part of the sheet on which the image iA is printed (see FIG. 43A).

  When the characteristic parameter output chart is output, the output characteristic parameter acquisition chart is read, and the process proceeds to the characteristic parameter acquisition step S128 of acquiring the characteristic parameter by analyzing the read image of the characteristic parameter acquisition chart. The characteristic parameter acquiring step S128 shown in FIG. 42 is a step of reading the characteristic parameter acquiring chart (step S11) shown in FIG. 4, and the read image acquired in step S11 is analyzed to relate the characteristics of the printing system. This process is the same as the process of acquiring the characteristic parameter (step S12), and the description thereof is omitted here.

  When the characteristic parameter is acquired, in the halftone process generation step S130, two or more types of halftone process rules having different priorities of requirements for halftone process are generated. Furthermore, in the halftoning rule determination step S132, the halftoning rule jA + 1 is determined based on the priority parameter.

  The halftone process generation step S130 shown in FIG. 42 is the same as the process shown in FIG. 4 for generating two or more types of halftone process rules having different priorities of required items for the halftone process (step S14). Also, the halftone processing rule determination step S132 shown in FIG. 42 has the same contents as the step (step S17) in which one type of halftone processing rule is determined based on the priority parameter shown in FIG.

  In the updating step S136, the image number is updated from iA to iA + 1. Also, the halftoning rule number is updated from jA to jA + 1. The update of the image number includes both when the content of the image is changed and when the content of the image is not changed. When the halftoning rule number is updated from jA to jA + 1, the halftoning rule jA and the halftoning rule jA + 1 may have the same content.

  When the image number and the halftone processing rule number are updated, the process proceeds to a determination step S124, and the steps from the determination step S124 to the update step S136 are repeatedly executed.

  In FIG. 42, the aspect in which the determination step S124 is performed is exemplified in the step subsequent to the image output step S122. However, the determination step S124 may be a step subsequent to the chart output step S126 for characteristic parameter acquisition or may be halftone processed. It may be the next process of the rule determination process S132.

  FIG. 43A is a conceptual diagram of a method of generating halftone processing rules according to the fifth embodiment. HT in FIG. 43A represents a halftone processing rule. The same applies to FIG. 43 (B).

  The top row of FIG. 43A represents an image iA output together with a characteristic parameter acquisition chart (chart kA). The image iA is halftoned using a halftone processing rule jA (HTjA). Through the characteristic parameter acquisition step S128 and the halftone processing generation step S130 shown in FIG. 42, the halftone processing rule jA + 1 (HTjA + 1) is generated based on the characteristic parameter acquisition chart kA shown in FIG. 43 (A). The halftoning rule jA is generated based on the characteristic parameter acquisition chart (chart kA-1) output accompanying the image iA-1 not shown.

  The middle part of FIG. 43A represents the image iA + 1 output together with the characteristic parameter acquisition chart (chart kA + 1). The image iA + 1 is halftone-processed using the halftone processing rule jA + 1 (HTjA + 1) generated based on the characteristic parameter acquisition chart kA.

  Through the characteristic parameter acquisition step S128 and the halftone processing generation step S130 shown in FIG. 42, the halftone processing rule jA + 2 (HTjA + 2) is generated based on the characteristic parameter acquisition chart kA + 1 shown in FIG. 43 (A).

  The lowermost part of FIG. 43A represents an image iA + 2 output together with a characteristic parameter acquisition chart (chart kA + 2). The image iA + 2 is halftoned using the halftone processing rule jA + 2 (HTjA + 2) generated based on the characteristic parameter acquisition chart kA + 1.

  Through the characteristic parameter acquisition step S128 and the halftone processing generation step S130 shown in FIG. 42, the halftone processing rule jA + 3 (HTjA + 3) is generated based on the characteristic parameter acquisition chart kA + 2 shown in FIG.

  According to the method of generating halftone processing rules according to the fifth embodiment, during acquisition of an arbitrary print job, the characteristic parameter acquisition chart used to generate halftone processing rules to be used for the image to be output next By outputting the image data together with the image, it is possible to determine the characteristic variation of the printing system for each image output (each of the characteristic parameter acquisition chart output), and the halftone processing rule corresponding to the characteristic variation of the printing system. Can be generated.

  As a result, by outputting an image using the halftone processing rule corresponding to the characteristic fluctuation of the printing system, it is possible to avoid the deterioration of the image quality even when the characteristic fluctuation of the printing system occurs.

  FIG. 43A exemplifies an aspect in which the chart for characteristic parameter acquisition is output on the same sheet as the sheet on which the image is output, as an aspect in which the chart for characteristic parameter acquisition is output accompanying the image output. It is also possible to apply a mode in which the characteristic parameter acquisition chart is output to a sheet subsequent to the sheet on which the image is output and before the next image is output.

Application of Halftoning Rule Generation Method According to Fifth Embodiment
Next, an application example of the method of generating halftone processing rules according to the fifth embodiment will be described. A process (output process) of outputting a chart for acquiring characteristic parameters by applying the method of generating halftone processing rules described with reference to FIGS. 42 and 43 (A), a chart for acquiring characteristic parameters is read, and characteristic parameters Processing for acquiring a characteristic parameter acquisition chart by performing parallel processing of any one or more of the processing for acquiring the image and the processing for generating the halftone processing rule and the halftone processing, for acquiring the characteristic parameter At least one of the process of reading the chart and acquiring the characteristic parameter and the process of generating the halftone process rule may perform one or more processes and the halftone process in the same period.

  FIG. 43B is a conceptual diagram of a method of generating halftone processing rules according to an application example of the fifth embodiment. In FIG. 43 (B), the same parts as in FIG. 43 (A) are assigned the same reference numerals and descriptions thereof will be omitted as appropriate.

  The top row of FIG. 43 (B) represents the image iA output together with the characteristic parameter acquisition chart (chart kA). The image iA is halftoned using a halftone processing rule jA (HTjA). The characteristic parameter acquisition chart kA output together with the image iA is a characteristic parameter acquisition used when generating a halftone processing rule applied to halftone processing of the image iA + 2 output after two images of the image iA Chart.

  Through the characteristic parameter acquisition step S128 and the halftone processing generation step S130 shown in FIG. 42, the halftone processing rule jA + 2 (HTjA + 2) is generated based on the characteristic parameter acquisition chart kA shown in FIG. 43 (B).

  The middle part of FIG. 43B represents the image iA + 1 output together with the characteristic parameter acquisition chart (chart kA + 1). The image iA + 1 is halftone-processed using the halftone processing rule jA + 1 (HTjA + 1) generated based on the characteristic parameter acquisition chart kA-1 (not shown).

  Through the characteristic parameter acquisition step S128 and the halftone processing generation step S130 shown in FIG. 42, the halftone processing rule jA + 3 (HTjA + 3) is generated based on the characteristic parameter acquisition chart kA + 1 shown in FIG. 43 (B).

  The lowermost part of FIG. 43B represents the image iA + 2 output together with the characteristic parameter acquisition chart (chart kA + 2). The image iA + 2 is halftoned using the halftone processing rule jA + 2 (HTjA + 2) generated based on the characteristic parameter acquisition chart kA.

  Through the characteristic parameter acquisition step S128 and the halftone processing generation step S130 shown in FIG. 42, the halftone processing rule jA + 4 (HTjA + 4) is generated based on the characteristic parameter acquisition chart kA + 2 shown in FIG. 43 (B).

  That is, in the method of generating a halftone processing rule shown in FIG. 43 (B), the halftone processing used for the halftone processing is added to the image output two images before the image to be halftone processed. The characteristic parameter acquisition chart used to generate the rule is output. In other words, the halftone processing generation unit 58 (see FIG. 37) generates a halftone processing rule using the characteristic parameter acquisition chart attached to the image two images before the image to be halftoned.

  In FIG. 43 (B), for acquiring characteristic parameters used to generate a halftone processing rule to be used for the halftone processing in addition to an image output before two images to be halftone processed. Although the manner in which the chart is output is illustrated, it is used to generate a halftone processing rule to be used for the halftone processing in addition to the image output two or more images before the image to be halftone processed. It is also possible to output a characteristic parameter acquisition chart.

  Therefore, during the halftone processing of the image iA + 1, the halftone processing rule jA + 2 to be applied to the halftone processing of the image iA + 2 can be generated based on the characteristic parameter acquisition chart kA.

  Like the method of generating halftone processing rules shown in FIG. 43 (B), based on the characteristic parameter acquisition chart, for halftone processing of an image two or more images later than the image accompanied by this characteristic parameter acquisition chart When generating the halftone processing rule to be used, it is possible to simultaneously execute the halftone processing of the image after one image and the generation of the halftone processing rule used for the halftone processing of the image after two or more images by parallel processing. In other words, when nB is an integer of 2 or more, the halftone processing rule jA + nB is generated from the characteristic parameter acquisition chart kA attached to the image iA which is the processing result of the halftone processing using the halftone processing rule jA. In this case, halftoning and generation of halftoning rules can be performed simultaneously in parallel processing, and productivity can be improved. However, since the halftone processing rule 1 to the halftone processing rule nB-1 are not generated based on the characteristic parameter acquisition chart output together with the image output, the halftone processing rule 0 (set first Halftoning rules apply).

  FIG. 44 is a flowchart of a method of generating halftone processing rules according to an application example of the fifth embodiment. In FIG. 44, the same steps as in FIG. 42 are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

  In the initialization step S121 shown in FIG. 44, zero is substituted for iA representing the image number, zero is substituted for jA representing the halftone processing rule number, and zero is substituted for the characteristic parameter acquisition chart number kA.

  The image output step S122 and the determination step S124 shown in FIG. 44 are the same as the image output step S122 and the determination step S124 shown in FIG. 42, and the description thereof is omitted here.

  In the determination step S124 shown in FIG. 44, when the determination is No (all outputs of the image iA are not completed), the process proceeds to the characteristic parameter acquisition chart output step S140 and the halftone processing step S148. The characteristic parameter acquisition chart output step S140 outputs the characteristic parameter acquisition chart kA along with the image iA.

  The characteristic parameter acquisition step S142 reads the characteristic parameter acquisition chart kA output in the characteristic parameter acquisition chart output step S140, and acquires a characteristic parameter.

  The halftone processing generation step S144 generates two or more types of halftone processing rules having different request items based on the characteristic parameters acquired in the characteristic parameter acquisition step S142.

  The halftone processing rule determination step S146 is applied to halftone processing of the image iA + 2 based on the priority parameter from among the two or more types of halftone processing rules with different requirement items generated in the halftone processing generation step S144. Determine the halftoning rule jA + 2. The halftone processing rule jA + 2 is stored in the halftone processing rule storage unit shown in FIG. 3 or FIG. 37 (halftone processing rule storage step).

  The halftone processing step S148 performs halftone processing using the halftone processing rule jA + 1 and outputs an image iA + 1. The halftoning rule jA + 1 is the default halftoning rule (halftoning rule 0) in the case of jA = 0, and in the case of jA> 0, acquisition of characteristic parameters output together with the image iA-1 It is a halftone processing rule generated based on the chart kA-1.

  In the halftone processing rule generation method shown in FIG. 44, the halftone processing step S148 is a series of steps for generating a halftone processing rule, characteristic parameter acquisition chart output step S140, characteristic parameter acquisition step S142, half processing A halftone processing rule that can be executed in the same period as the tone processing generation step S144 and the halftone processing rule determination step S146, and is applied to the halftone processing of the image iA + 2 in parallel with the halftone processing of the image iA + 1 jA + 2 can be generated.

  In the updating step S150, the image number is updated from iA to iA + 1. Also, the halftoning rule number is updated from jA to jA + 1. Furthermore, the characteristic parameter acquisition chart number is updated from kA to kA + 1.

  According to the method of generating halftone processing rules according to the application example of the fifth embodiment configured as described above, variation in the characteristics of the printing system is achieved by performing parallel processing of halftone processing and halftone processing rule generation. Enhance the productivity of the printing system as compared to sequential processing of the generation of the halftone processing rule reflecting the parameter and the halftone processing applying the halftone processing rule reflecting the fluctuation of the characteristic of the printing system Is possible.

<Description of Modification of Method of Generating Halftone Processing Rule According to Application of Fifth Embodiment>
FIG. 45 is a flowchart of a first modified example of the method of generating halftone processing rules according to the application example of the fifth embodiment. FIG. 46 is a flowchart of a second modification of the method of generating halftone processing rules according to the application of the fifth embodiment. In FIG. 45 and FIG. 46, the same steps as in FIG. 44 are given the same reference numerals, and the description thereof will be omitted as appropriate.

  As shown in FIGS. 45 and 46, the method of generating halftone processing rules shown in FIG. 44 can be changed in consideration of the balance of parallel processing. As an example of the balance of parallel processing, there may be mentioned balance of processing period and balance of processing load.

  In the method of generating halftone processing rules according to the first modification shown in FIG. 45, the halftone processing generation step S144 and the halftone processing rule determination step S146 of the generation method of halftone processing rules shown in FIG. The characteristic parameter storage step S143 is added after the characteristic parameter acquisition step S142, and the halftone processing generation step S154 and the halftone processing rule determination step S156 are added before the halftone processing step S148.

  In the method of generating halftone processing rules shown in FIG. 45, when the characteristic parameters used in generating the halftone processing rule jA + 2 are acquired based on the characteristic parameter acquisition chart kA in the characteristic parameter acquisition step S142, The characteristic parameter is stored in the characteristic parameter storing step S143, and the process proceeds to the updating step S150. The characteristic parameters are stored in the characteristic parameter storage unit 54 shown in FIG.

  If NO in the determination step S124 shown in FIG. 45 (all outputs of the image iA have not been completed), the process proceeds to a characteristic parameter acquisition chart output step S140 and a halftone process generation step S154. In the halftoning process generation step S154, based on the characteristic parameter acquired from the characteristic parameter acquisition chart kA-1 output together with the image iA-1 (an image output immediately before the image iA), a required item Two or more types of halftone processing rules with different priorities are generated.

  The halftoning rule determination step S156 performs halftoning of the image iA + 1 based on the priority parameter among the two or more types of halftoning rules having different priorities of the request item generated in the halftoning generation step S154. Generate the halftoning rule jA + 1 applied to.

  The halftone processing step S148 performs halftone processing using the halftone processing rule jA + 1 determined in the halftone processing rule determination step S156, and outputs an image iA + 1. When the image iA + 1 is output in the halftone processing step S148 and the characteristic parameters used in generating the halftone processing rule jA + 2 are stored in the characteristic parameter storing step S143, the process proceeds to the updating step S150.

  In the first image output, the halftone processing generation step S154 and the halftone processing rule determination step S156 are omitted, and instead of the halftone processing step S148, “halftone processing using halftone processing rule 0 is performed. , “Output image 1” processing is performed.

  The method of generating halftone processing rules according to the second modification shown in FIG. 46 is a step after the image output step S122 of the method of generating halftone processing rules shown in FIG. In the process of the step i, a chart for characteristic parameter acquisition chart output step S140 for outputting the chart k for characteristic parameter acquisition accompanying the image iA is performed.

  In the method of generating a halftoning rule shown in FIG. 46, a chart for characteristic parameter acquisition is output from the first image accompanied with it. Note that the image output step S122 and the characteristic parameter acquisition chart output step S140 shown in FIG. 46 can be combined into one step.

  In the determination step S124 shown in FIG. 46, if the determination is No (all outputs of the image iA are not completed), the process proceeds to the characteristic parameter acquisition step S142 and the halftone processing step S148.

  When the image iA + 1 is output in the halftone processing step S148, the process proceeds to a characteristic parameter acquisition chart output step S160. The characteristic parameter acquisition chart output step S160 outputs the characteristic parameter acquisition chart kA + 1 along with the image iA + 1.

  In the updating step S162 shown in FIG. 46 provided instead of the updating step S150 shown in FIG. 44, the image number is updated from iA to iA + 1. Also, the halftoning rule number is updated from jA to jA + 1. Furthermore, the characteristic parameter acquisition chart number is updated from kA to kA + 1.

  The method of generating halftone processing rules shown in FIG. 44, FIG. 45, and FIG. 46 performs halftone processing on an image after two images rather than the image accompanied by the characteristic parameter acquisition chart based on the characteristic parameter acquisition chart. In the same way, it is also possible to generate a halftoning rule for halftoning an image after an nB image by setting an integer of 2 or more to nB.

  Specifically, in the halftone processing rule determination step S146 shown in FIGS. 44 and 46, “halftone processing rule jA + nB” may be determined instead of “halftone processing rule jA + 2”. In the halftoning rule generation method shown in FIG. 45, “halftoning rule jA + nB−1” may be determined instead of “halftoning rule jA + 1” in the halftoning rule determination step S156. The halftone processing step S148 shown in FIGS. 44, 45 and 46 is not required to be changed.

  However, in the method of generating halftone processing rules shown in FIGS. 44, 45 and 46, the processes from halftone processing rule 1 (jA = 1) to halftone processing rule nB-1 accompany the image output. Since no halftone processing rule is generated based on the output characteristic parameter acquisition chart, the halftone processing rule 0 (halftoning rule initially set) is substituted for the halftone processing rule jA + 1 in the halftone processing step S148. Halftone processing is performed using. Further, in the method of generating halftone processing rules shown in FIG. 45, the halftone processing generation step S154 and the halftone processing rule determination step S156 are omitted.

  In the method of generating halftone processing rules shown in FIGS. 42, 44, 45, and 46, an image and a halftone processing rule correspond to each other in a one-to-one manner. That is, the halftone processing rule is changed when the image changes. However, that is not necessary. One halftoning rule can be applied to multiple images. For example, apply halftone processing rule 1 to image 1, image 2, image 3 and image 4 and apply halftone processing rule 2 to image 5, image 6, image 7 and image 8. Can.

  That is, productivity can be improved by updating the halftone processing rule once for each of a plurality of image (a plurality of images) output. When the halftone processing rule is updated once for each of a plurality of images (a plurality of images), the characteristic parameter acquisition chart may be output along with any of the plurality of images.

  Then, halftoning and halftoning are performed by separating the image to be accompanied by the characteristic parameter acquisition chart and the image to be halftoned using the halftone processing rule generated based on the characteristic parameter acquisition chart by two or more images. As described above, the productivity can be further improved by simultaneously performing the generation of processing rules in parallel processing.

  According to the method of generating halftone processing rules according to the first and second modifications, it is possible to obtain the same effect as the method of generating halftone processing rules according to the application of the fifth embodiment. It is possible to optimize the distribution of parallel processing time and the distribution of processing load according to the configuration of the printing system.

[Description of Chart Output for Characteristic Parameter Acquisition According to Sixth Embodiment]
<Configuration of Image Processing Device>
FIG. 47 is a block diagram showing the configuration of an image processing apparatus applied to a printing system according to the sixth embodiment. In FIG. 47, the control unit 50 is shown in two places for convenience of illustration. The two control units 50 shown in FIG. 47 do not limit the function, structure, and the like. Acquisition of characteristic parameters according to the sixth embodiment includes generation of a chart for characteristic parameter acquisition based on the characteristic parameters regarding the system specification stored in the characteristic parameter storage unit 54, output of the characteristic parameter acquisition chart, and characteristic parameter acquisition. A characteristic parameter is newly acquired through reading of the chart and analysis of a read image of the characteristic parameter acquisition chart.

  Characteristic parameters relating to system specifications are determined based on the system specifications. In other words, it is a characteristic parameter obtained without using a characteristic parameter acquisition chart.

  Examples of the characteristic parameters relating to the system specification include the resolution described above, the number of nozzles (the number of used nozzles), the type of ink, the type of droplets, and whether unidirectional scanning or bidirectional scanning. In the present embodiment, characteristic parameters relating to system specifications are described as system specification parameters.

  Among the characteristic parameters, characteristic parameters other than the system specification parameters are characteristic parameters obtained using the characteristic parameter acquisition chart.

  Examples of characteristic parameters other than system specification parameters include dot density of each printing element, dot diameter, dot shape, dot formation position deviation, non-ejection, and the like. Other examples of characteristic parameters other than system specification parameters include average dot density, average dot diameter, and average dot shape of a plurality of printing elements. As another example of characteristic parameters other than system specification parameters, dot formation position deviation for each droplet type, bidirectional printing position deviation, head vibration error, print medium conveyance error, head module in head constituted by a plurality of head modules Vibration error, landing interference, etc. may be mentioned.

  Here, instead of generating the characteristic parameter acquisition chart, among the characteristic parameter acquisition charts stored in the characteristic parameter acquisition chart storage unit 242, the characteristic parameter acquisition chart corresponding to the acquired system specification parameter You may choose.

  The characteristic parameter storage unit 54 corresponds to a characteristic parameter storage unit. The characteristic parameter acquisition chart generation unit 62 corresponds to a characteristic parameter acquisition chart generation unit. The configuration for selecting the characteristic parameter acquisition chart instead of generating the characteristic parameter acquisition chart by the characteristic parameter acquisition chart generation unit 62 corresponds to the characteristic parameter acquisition chart selection means. The characteristic parameter acquisition chart storage unit 242 corresponds to a characteristic parameter acquisition chart storage unit.

  In the embodiment described below, an aspect will be described in which a characteristic parameter acquisition chart is generated or selected according to the selection of the printing mode.

  The image processing apparatus 21 shown in FIG. 47 includes a print mode selection unit 240, a characteristic parameter acquisition chart storage unit 242, and a chart output condition setting unit 244 in addition to the image processing apparatus 20 shown in FIG. .

  The print mode selection unit 240 selects a print mode in printing performed by the data output unit 66 and the printing apparatus 24 shown in FIG. As an example of selection of the print mode, it is automatically selected from information such as the mode in which the operator manually selects the print mode via the input device 34 shown in FIG. 3, the input image data, the type of print medium, etc. And the like.

  When the print mode is selected, the system specification parameter corresponding to the selected print mode is read out and acquired from the system specification parameters stored in the characteristic parameter storage unit 54. The characteristic parameter acquisition chart generation unit 62 generates a characteristic parameter acquisition chart based on the acquired system specification parameters.

  When the characteristic parameter acquisition chart is generated, the chart output condition for the printing mode selected by the chart output condition setting unit 244 is set, and the characteristic parameter acquisition is performed by the data output unit 66 and the printing apparatus 24 shown in FIG. Chart is output.

  Instead of generating the characteristic parameter acquisition chart, the characteristic parameter acquisition chart corresponding to the acquired system specification parameter is selected from the characteristic parameter acquisition charts stored in advance in the characteristic parameter acquisition chart storage unit 242. Aspects are also possible.

<Specific example of chart generation for characteristic parameter acquisition, and selection>
Next, a specific example of chart selection for characteristic parameter acquisition will be described. The characteristic parameter acquisition chart generation unit 62 shown in FIG. 47 generates a unit chart composed of a single dot pattern and a continuous pattern. A unit chart is a unit chart which comprises the chart for characteristic parameter acquisition, and is a necessary minimum chart. As an example of a single dot pattern in the case of serial scan, single dot patterns 102C, 102M, 102Y, 102K shown in FIG. 5 can be mentioned. As an example of a single dot pattern in the case of a single pass, single dot patterns 202C, 202M, 202Y and 202K shown in FIG. 21 can be mentioned.

  Examples of continuous dot patterns in the case of serial scan include the first continuous dot patterns 104C, 104M, 104Y, and 104K, and the second continuous dot patterns 106C, 106M, 106Y, and 106K illustrated in FIG. Examples of continuous dot patterns in the case of single pass include the first continuous dot patterns 204C, 204M, 204Y and 204K and the second continuous dot patterns 206C, 206M, 206Y and 206K shown in FIG.

  When the print mode is selected by the print mode selection unit 240 shown in FIG. 47, the characteristic parameter acquisition chart generation unit 62 generates a unit chart, and further, based on the system specification parameters corresponding to the selected print mode. By arranging the unit charts, a chart for characteristic parameter acquisition suitable for the system specification parameter corresponding to the print mode is generated.

  The generated characteristic parameter acquisition chart is stored in the characteristic parameter acquisition chart storage unit 242 using the print mode or the system specification parameter as an index. When there is a chart for characteristic parameter acquisition applicable to the selected print mode or a chart for characteristic parameter acquisition applicable to the system specification parameter corresponding to the selected print mode when the print mode is selected. Instead of the generation of the characteristic parameter acquisition chart described above, the characteristic parameter acquisition chart applicable to the selected print mode or the characteristic parameter acquisition chart applicable to the system specification parameter corresponding to the print mode is selected. Ru.

<Specific example of system specification parameters corresponding to print mode and print mode>
(1) The high image quality mode is selected, and the ink types used in the high image quality mode are cyan, magenta, yellow, black, light cyan, light magenta, the type of droplets used is only small droplets, and the scanning direction is unidirectional. For scanning The unit charts of cyan ink droplets, magenta ink droplets, yellow ink droplets, black ink droplets, light cyan ink droplets, and light magenta ink droplets are arranged for the forward scan A chart is generated. Furthermore, a continuous dot pattern may be generated by combining cyan ink droplets, magenta ink droplets, yellow ink droplets, black ink droplets, light cyan ink droplets, and light magenta ink droplets. .

  Chart for characteristic parameter acquisition when ink type of high quality image mode is cyan, magenta, yellow, black, light cyan, light magenta, and droplet type is only small droplet, unidirectional scanning in the chart storage unit for characteristic parameter acquisition If the ink type in the high-quality mode is cyan, magenta, yellow, black, light cyan, or light magenta, and the droplet type is small droplets only, the chart for characteristic parameter acquisition in the case of unidirectional scanning is selected. Be done.

(2) The standard image quality mode is selected, and the standard image quality mode ink types used are cyan, magenta, yellow and black, and the droplet types used are small, medium and large drops, and the scanning direction is In the case of bi-directional scanning A unit chart is generated for small, medium, and large droplets of cyan, magenta, yellow, and black inks, and a chart for characteristic parameter acquisition is generated in which only forward and backward scans are arranged. Ru. Furthermore, a continuous dot pattern may be generated by combining small, medium, and large droplets of cyan, magenta, yellow, and black inks.

  In the characteristic parameter acquisition chart storage unit 242, the ink types in the standard image quality mode are cyan, magenta, yellow, and black, the droplet types used are small, medium, and large, and the scanning direction is bidirectional. When a chart for acquiring characteristic parameters in the case of scanning is stored, ink types in the standard image quality mode are cyan, magenta, yellow and black, and drop types used are small, medium and large drops. If the scanning direction is bi-directional scanning, the chart for characteristic parameter acquisition is selected.

(3) When the monochrome mode is selected and the ink type used in the monochrome mode is black only, and the droplet types used are droplets, medium droplets, and large droplets, and the scanning direction is bidirectional scanning black For the ink, unit charts of small droplets, middle droplets, and large droplets are generated, and a characteristic parameter acquisition chart is generated in which the amount of forward scanning and the amount of backward scanning are arranged. Furthermore, a continuous dot pattern may be generated by combining black ink droplets, medium droplets, and large droplets.

  In the characteristic parameter acquisition chart storage unit 242, when the ink type in monochrome mode is black, the droplet types used are small, medium, and large droplets, and the characteristic parameter acquisition when the scanning direction is bidirectional scanning When the chart for the image is stored, the ink type in monochrome mode is black, the types of droplets used are droplets, medium droplets, and large droplets, and acquisition of characteristic parameters when the scanning direction is bidirectional scanning Chart is selected.

  When the nozzles used are different depending on the print mode, the content of the unit chart is different for each print mode. When outputting the characteristic parameter acquisition chart, the chart output condition setting unit 244 sets the scanning speed, the sheet conveyance amount, and the discharge frequency corresponding to the selected print mode as the chart output condition. The scanning speed is the speed of the recording head when scanning the recording head in the main scanning direction. The transport amount of the print medium is a distance by which the print medium moves in one transport in the sub scanning direction, and is a value represented by a reciprocal of a substantial resolution in the sub scanning direction.

<Relationship between generation and selection of characteristic parameter acquisition chart>
If the characteristic parameter acquisition chart storage unit 242 shown in FIG. 47 has a sufficient storage capacity, a chart corresponding to the system specification parameter can be generated and stored in advance for each print mode.

  On the other hand, when the storage capacity of the characteristic parameter acquisition chart storage unit 242 shown in FIG. 47 is insufficient, the provision of a sufficient storage capacity in the characteristic parameter acquisition chart storage unit 242 requires a large cost, or When the generation period of the acquisition chart can be short, the characteristic parameter acquisition chart can be generated.

  For frequently selected print modes, it is also possible to generate and store characteristic parameter acquisition charts in advance, and to generate characteristic parameter acquisition charts as needed for print modes that are selected less frequently. .

  For example, the characteristic parameter acquisition chart for the selected print mode is generated for the print mode selected when performing any printing, and the characteristic parameter acquisition chart storage unit 242 shown in FIG. 47 generates the characteristic parameter acquisition chart. The parameter acquisition chart is stored for a fixed period. When the same print mode is selected again during a certain period, the chart for characteristic parameter acquisition for that print mode stored in the chart for characteristic parameter acquisition chart 242 is selected, and for that print mode. The characteristic parameter acquisition chart is stored for a certain period of time from the time of reselection. After the certain period has elapsed, the characteristic parameter acquisition chart is deleted. After the characteristic parameter acquisition chart is deleted, when the print mode is set next, a characteristic parameter acquisition chart is newly generated and stored for a certain period. In this manner, it is possible to determine the period in which the characteristic parameter acquisition chart is stored, and switch the generation and selection of the characteristic parameter acquisition chart in accordance with the period in which the characteristic parameter acquisition chart is stored. .

<Variation of system configuration>
A means for acquiring characteristic parameters relating to the characteristics of the printing system, that is, a device for the user to input characteristic parameters, a chart output control device for outputting the characteristic parameter acquisition chart, and the characteristic parameter acquisition chart according to the control thereof. A printing apparatus for printing, an apparatus for reading characteristic parameter acquisition charts, and an apparatus for acquiring characteristic parameters based on an analysis result of the read image, an apparatus for generating two or more types of halftone processing rules, a halftone selection chart A chart output control device for outputting the image, a device for generating a simulation image from the halftone processing result of the halftone selection chart, reading the output result of the halftone selection chart, and calculating an image evaluation value from the chart read image Device, user half Each device may be configured as an integrated system, such as an apparatus for performing an operation to select an on-line processing rule, or it is a decentralized system in which functions are separated and a plurality of systems are combined. It may be configured.

  Similarly, the configurations of the image processing apparatus 20 described with reference to FIG. 36, the image processing apparatus 20A described with reference to FIG. 37, and the image processing apparatus 21 described with reference to FIG. A plurality of systems may be configured as a combined separate system.

  [Modification 1 of System Configuration] For example, the apparatus for performing the process of acquiring the characteristic parameter and the apparatus for performing the process of generating the halftone process rule can be configured as separate apparatuses.

  [Modification 2 of System Configuration] Further, the apparatus for performing the process of outputting the halftone selection chart and the apparatus for the user to perform the selection operation of the halftone process can be configured as separate apparatuses.

  [Modification 3 of system configuration] Also, the apparatus for acquiring the characteristic parameter and the apparatus for generating the halftoning rule by holding the priority parameter may be configured as separate apparatuses. it can.

  [Modification 4 of System Configuration] As another configuration example, an apparatus that performs processing for outputting a characteristic parameter acquisition chart, an image reading apparatus that reads the output characteristic parameter acquisition chart, and a characteristic parameter acquisition chart An apparatus that performs processing of generating and acquiring characteristic parameters from the read image and an apparatus that performs processing of generating halftone processing rules using the acquired characteristic parameters can be configured by separate apparatuses.

  Also, for example, output of characteristic parameter acquisition charts and halftone selection charts, and processing of image reading of the charts are performed by the printer manufacturer's factory or printing company individual local printing system, and the acquired readings After sending the images at once to a server of a development department or a printer maker of another company, acquisition of characteristic parameters and generation of halftone processing rules were implemented by the system of the development department or another company, and generated It is also possible to send halftone processing rules back to the original individual local printing system.

<Other configuration example>
The following configurations can be adopted for the above-described embodiment.

  [Configuration Example 1] Every time a new print job is executed, or while a print job is being executed, a chart output is automatically performed, and a system error parameter is acquired from the reading result of the chart, and based on the acquired parameter Halftoning rules may be generated. Chart output and reading are performed for each print job and / or during the print job, and halftone generation is newly performed only when the system error parameter changes beyond a specified reference or only the changed part. It may be a configuration to be performed. In this case, if there is no change in the system error parameter (including the characteristic parameter), that is, if the amount of change in the system error parameter falls within the specified criteria, the halftone processing rule generation process is omitted and the time There is no serious loss.

  Also, chart output may be performed in addition to the image before the image to be halftone-processed. In this case, time loss is reduced. Furthermore, halftoning and halftoning rule generation may be parallelized.

  [Configuration Example 2] Chart contents, chart output conditions, scan conditions (equivalent to chart reading conditions), parameter acquisition method, and halftone processing rule according to the user's quality request for the print image acquired by the quality request acquisition unit One or more combinations of the generated contents of may be changed. By adopting such a configuration, it is possible to reduce the loss of time required for processing.

  [Configuration example 3] A dedicated chart (dot replication precision survey dedicated chart) for examining dot reproducibility is output by the dot recall accuracy dedicated chart output unit, and from the dot replication precision survey dedicated chart, the dot reproducibility accuracy analyzing section The dot reproduction accuracy is analyzed, and based on the analysis result, any one or a combination of the contents of the parameter acquisition chart, chart output conditions, scan conditions, parameter acquisition method, and halftone processing rule generation contents May be changed. By adopting such a configuration, it is possible to reduce the loss of time required for processing.

<About a program that causes a computer to function as an image processing apparatus>
As an image processing apparatus described in the above embodiment, a program for causing a computer to function is a compact disc read-only memory (CD-ROM), a magnetic disk, and other computer readable media (non-transitory information storage medium that is a tangible object) And the program can be provided through the information storage medium. Instead of storing and providing the program in such an information storage medium, it is also possible to provide a program signal as a download service using a communication network such as the Internet.

  By incorporating this program into a computer, the computer can realize the functions of the image processing apparatus 20. In addition, an aspect in which a part or all of a program for realizing printing control including the image processing function described in the present embodiment is incorporated in a host control device such as a host computer, a central processing unit (CPU It is also possible to apply as an operation program of.

<< About print media >>
The term "print medium" includes those called in various terms such as print medium, print medium, image formation medium, image receiving medium, discharge medium, recording paper, and the like. In the practice of the present invention, the material and shape of the print medium are not particularly limited, and continuous sheets, cut sheets, seal sheets, resin sheets such as OHP (overhead projector) sheets, films, cloths, nonwoven fabrics, wiring patterns, etc. Various sheet bodies can be used regardless of the printed circuit board to be formed, the rubber sheet, and other materials and shapes.

<< Image quality degradation >>
The "image quality deterioration" in the present specification mainly indicates the occurrence of streaks and unevenness, and the deterioration of granularity. The image quality deterioration may be caused by various factors such as ink aggregation unevenness, gloss unevenness, density, color or banding, banding of these combinations, or bleeding.

<< About the combination of the embodiments >>
It is possible to employ the composition which combined suitably the composition explained as each embodiment mentioned above, modification, or other example of composition. For example, with regard to the configuration of the fourth embodiment and the configuration of the modification of the fourth embodiment, the configurations of the first to third embodiments can be combined as appropriate.

<Advantage of Embodiment>
According to the embodiment described above, there are the following advantages.

  (1) Various characteristic parameters related to the characteristics of the printing system can be easily acquired from the read image of the characteristic parameter acquisition chart. As a result, compared with the configuration in which the user inputs all of the various characteristic parameters from the user interface, the workload on the user regarding setting of the characteristic parameters can be significantly reduced. Then, based on the characteristic parameters acquired from the characteristic parameter acquisition chart, it is possible to generate a halftone processing rule suitable for the printing system.

  (2) A halftone processing rule suitable for the printing system can be generated in consideration of a system error in which actual printing by the printing system is assumed. As a result, it is possible to realize appropriate halftone processing that can obtain good image quality, and to obtain a print image of good image quality.

  (3) Since the characteristic parameter is updated according to the difference between the existing characteristic parameter and the new characteristic parameter, the characteristic parameter can be updated according to the fluctuation of the characteristic of the printing system. As a result, by generating the halftone process rule using the updated characteristic parameter, it is possible to perform printing using the halftone process rule corresponding to the change of the characteristic of the printing system.

  (4) According to the generation method of the processing rule, the chart for characteristic parameter acquisition to be used for generating the halftone processing rule to be used for the image to be output next is attached to the image during execution of any print job. By outputting as it is, characteristic fluctuation of the printing system can be judged for every image output (every chart output for characteristic parameter acquisition), and a halftone processing rule corresponding to characteristic fluctuation of the printing system can be generated. As a result, by outputting an image using the halftone processing rule corresponding to the characteristic fluctuation of the printing system, it is possible to avoid the deterioration of the image quality even when the characteristic fluctuation of the printing system occurs.

  In the embodiment of the present invention described above, it is possible to appropriately change, add, or delete the constituent requirements without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications can be made within the technical concept of the present invention by those having ordinary knowledge in the relevant field.

  DESCRIPTION OF SYMBOLS 10 printing system 20, 20A, 21 image processing apparatus 24 printing apparatus 26 image reading apparatus 32 display apparatus 34 input apparatus 52 characteristic parameter acquisition part 53 system error parameter acquisition part 54: characteristic parameter storage unit 55: system error parameter storage unit 56: priority parameter storage unit 58: halftone processing generation unit 58A: previous stage halftone processing generation unit 58B: halftone automatic selection unit 59 judgment evaluation value calculation unit 60 halftone processing rule storage unit 62 characteristic parameter acquisition chart generation unit 64 image analysis unit 67 system error setting unit 70 evaluation value calculation unit 74 image quality Evaluation processing unit 76: Halftone selection chart generation unit 100: Characteristic parameter acquisition chart 101: Print medium 10 C, 102M, 102Y, 102K ... single dot pattern, 104C, 104M, 104Y, 104K ... first continuous dot pattern, 106C, 106M, 106Y, 106K ... second continuous dot pattern, 150 ... halftone selection chart , 151, 152 ... primary color patch, 200 ... characteristic parameter acquisition chart, 201 ... print medium, 202C, 202M, 202Y, 202K ... single dot pattern, 204C, 204M, 204Y, 204K ... first continuous dot pattern , 206C, 206M, 206Y, 206K ... second continuous dot pattern 230 ... characteristic parameter update determination unit 323 ... specified value acquisition unit

Claims (33)

Characteristic parameter acquisition chart output means for outputting a characteristic parameter acquisition chart including a pattern for acquiring a characteristic parameter related to a characteristic of a printing system;
An image reading unit for reading the characteristic parameter acquisition chart output by the characteristic parameter acquisition chart output unit;
Characteristic parameter acquisition means for acquiring the characteristic parameter by analyzing a read image of the characteristic parameter acquisition chart obtained by the image reading means;
A halftone processing generation unit that generates a halftone processing rule that defines processing content of halftone processing used in the printing system based on the characteristic parameter acquired through the characteristic parameter acquisition unit;
Equipped with
The printing system wherein the halftone processing generation unit respectively generates two or more types of halftone processing rules having different balances of priorities with respect to a plurality of requirement items required for halftone processing from the same characteristic parameter.   The printing system according to claim 1, wherein the plurality of requirements include at least two items of image quality, cost, halftone generation time, halftone processing time, tolerance to system error, and tolerance to environmental fluctuation. .   The halftone registration unit according to claim 1 or 2, further comprising: a halftone registration unit that registers the two or more types of halftone processing rules generated by the halftone processing generation unit as candidates for halftone processing usable in the printing system. Printing system described.   For halftone selection which outputs a halftone selection chart including an image area for comparison evaluation of the quality of each halftone process using the two or more types of halftone process rules generated by the halftone process generation means The printing system according to any one of claims 1 to 3, further comprising chart output means.   An evaluation value calculation unit that calculates an evaluation value for quantitatively evaluating at least one item among image quality, cost, halftone generation time, and halftone processing time of halftone processing defined by the halftone processing rule; The printing system according to any one of Items 1 to 4.   The printing system according to claim 5, further comprising: information presenting means for presenting information of the evaluation value to a user.   For the user to select the type of halftone processing used for printing from the types of halftone processing defined by the two or more types of halftone processing rules generated by the halftone processing generation means The printing system according to any one of claims 1 to 6, further comprising halftone selection operating means.   Among the types of halftone processing defined by the two or more types of halftone processing rules generated by the halftone processing generation means, the printing based on the priority parameter regarding the priority for the plurality of required items The printing system according to any one of claims 1 to 7, further comprising halftone automatic selection means for automatically selecting a type of halftone processing used for printing of the system.   The printing system according to claim 8, further comprising: a priority input unit for the user to input information on the priority of the plurality of request items. The halftone automatic selection means
It includes a judgment evaluation value calculation means for calculating, based on the priority parameter, a judgment evaluation value for evaluating the appropriateness of halftone processing defined by the halftone processing rule generated by the halftone processing generation means,
The printing system according to claim 8 or 9, wherein a type of halftone processing used for printing of the printing system is automatically selected based on the judgment evaluation value calculated by the judgment evaluation value calculation means. The halftone automatic selection means
Simulation image generation means for generating a simulation image when printing a halftone image obtained by applying halftone processing defined by the halftone processing rule generated by the halftone processing generation means;
An image quality evaluation value calculating unit that calculates an image quality evaluation value from the simulation image;
The printing system according to any one of claims 8 to 10, comprising:   The printing system according to any one of claims 8 to 11, further comprising priority parameter holding means for holding the priority parameter.   The printing system according to any one of claims 1 to 12, wherein the halftone processing rule is specified by a combination of a halftone algorithm and a halftone parameter.   The printing system according to claim 13, wherein any one of a dither method, an error diffusion method, and a direct binary search method is adopted as the halftone algorithm.   The halftone parameters include the size of a dither mask in dithering, the threshold, the size of an error diffusion matrix in error diffusion, the diffusion coefficient, and the setting of the applicable gradation section of each error diffusion matrix, and the pixels in direct binary search The printing system according to claim 13, wherein at least one parameter is included among the number of updates, the replacement pixel range, and the parameter for evaluating system error tolerance. A characteristic parameter acquisition chart output step of outputting a characteristic parameter acquisition chart including a pattern for acquiring a characteristic parameter related to the characteristic of the printing system;
An image reading step of reading the characteristic parameter acquisition chart output by the characteristic parameter acquisition chart output step;
A characteristic parameter acquisition step of acquiring the characteristic parameter by analyzing a read image of the characteristic parameter acquisition chart obtained by the image reading step;
A halftone processing generation step of generating a halftone processing rule that defines processing content of halftone processing used in the printing system based on the characteristic parameter acquired through the characteristic parameter acquisition step;
Including
The halftoning process of the halftoning process generates the two or more types of halftoning rules having different balances of priorities with respect to a plurality of requirement items required for halftoning from the same characteristic parameters. Generation method.   Among the types of halftone processing defined by the two or more types of halftone processing rules generated in the halftone processing generation step, the printing based on the priority parameter regarding the priority for the plurality of required items The method of generating halftone processing rules according to claim 16, further comprising an automatic halftone selection step of automatically selecting the type of halftone processing used for printing of the system.   The method according to claim 17, further comprising a priority input step for the user to input information on priorities for the plurality of requirement items. The automatic halftone selection step calculates, based on the priority parameter, a determination evaluation value for evaluating the appropriateness of halftone processing defined by the halftone processing rule generated in the halftone processing generation step. Including the judgment evaluation value calculation process,
The method of generating a halftone processing rule according to claim 17 or 18, wherein a type of halftone processing used for printing of the printing system is automatically selected based on the determination evaluation value calculated in the determination evaluation value calculating step. . The halftone automatic selection step is a simulation for generating a simulation image when printing a halftone image obtained by applying the halftone processing defined by the halftone processing rule generated in the halftone processing generation step. An image generation process,
An image quality evaluation value calculating step of calculating an image quality evaluation value from the simulation image;
20. A method of generating halftone processing rules according to any one of claims 17 to 19, comprising:   21. The method of generating halftone processing rules according to any one of claims 17 to 20, comprising a priority parameter holding step of holding the priority parameter. Characteristic parameter acquisition chart generating means for generating chart data of a characteristic parameter acquisition chart including a pattern for acquiring a characteristic parameter related to a characteristic of a printing system;
Characteristic parameter acquisition means for acquiring the characteristic parameter by analyzing a read image of the characteristic parameter acquisition chart printed by the printing system based on the chart data;
A halftone processing generation unit that generates a halftone processing rule that defines processing content of halftone processing used in the printing system based on the characteristic parameter acquired through the characteristic parameter acquisition unit;
Equipped with
The image processing apparatus, wherein the halftone processing generation unit generates two or more types of halftone processing rules having different balances of priorities with respect to a plurality of required items required for halftone processing from the same characteristic parameter.   Among the types of halftone processing defined by the two or more types of halftone processing rules generated by the halftone processing generation means, the printing based on the priority parameter regarding the priority for the plurality of required items 23. The image processing apparatus according to claim 22, further comprising automatic halftone selection means for automatically selecting the type of halftone processing used for printing of the system.   24. The image processing apparatus according to claim 23, further comprising a priority input unit for the user to input information on the priority of the plurality of request items. The automatic halftone selecting means calculates a judgment evaluation value for evaluating the appropriateness of the halftone process defined by the halftone process rule generated by the halftone process generating means, based on the priority parameter. Including a judgment evaluation value calculation means,
The image processing apparatus according to claim 23, wherein a type of halftone processing used for printing of the printing system is automatically selected based on the determination evaluation value calculated by the determination evaluation value calculation unit. The halftone automatic selection unit is configured to generate a simulation image when printing a halftone image obtained by applying the halftone processing defined by the halftone processing rule generated by the halftone processing generation unit. Image generation means,
An image quality evaluation value calculating unit that calculates an image quality evaluation value from the simulation image;
The image processing apparatus according to any one of claims 23 to 25, comprising:   The image processing apparatus according to any one of claims 23 to 26, further comprising priority parameter holding means for holding the priority parameter. Computer,
Characteristic parameter acquisition chart generating means for generating chart data of a characteristic parameter acquisition chart including a pattern for acquiring a characteristic parameter related to a characteristic of a printing system;
Characteristic parameter acquisition means for acquiring the characteristic parameter by analyzing a read image of the characteristic parameter acquisition chart printed by the printing system based on the chart data;
A halftone processing generation unit that generates a halftone processing rule that defines processing content of halftone processing used in the printing system based on the characteristic parameter acquired through the characteristic parameter acquisition unit, and is a halftone processing A program which causes two or more types of halftone processing rules having different balances of priorities with respect to a plurality of required items required to function as halftone processing generation means respectively generating from the same characteristic parameter. Computer,
Among the types of halftone processing defined by the two or more types of halftone processing rules generated by the halftone processing generation means, the printing based on the priority parameter regarding the priority for the plurality of required items The program according to claim 28, wherein the program functions as an automatic halftone selection means for automatically selecting the type of halftone processing used for printing of the system. Computer,
The program according to claim 29, wherein the program functions as a priority input unit for the user to input information related to the priorities of the plurality of request items. Computer,
The above-mentioned evaluation evaluation value calculation means for calculating the evaluation value for evaluating the appropriateness of the halftone process defined by the halftone process rule generated by the halftone process generation means based on the priority parameter A halftone automatic selection unit that automatically selects the type of halftone processing used for printing by the printing system based on the determination evaluation value calculated by the determination evaluation value calculation unit. 31. A program according to claim 29 or 30 which causes it to function. Computer,
Simulation image generation means for generating a simulation image when printing a halftone image obtained by applying halftone processing defined by the halftone processing rule generated by the halftone processing generation means; and the simulation image 32. The program according to any one of claims 29 to 31, wherein said program is functioned as said halftone automatic selection means, comprising: Computer,
The program according to any one of claims 29 to 32, functioning as priority parameter holding means for holding the priority parameter.