JP2007329842A - Color reproduction model creating method, storage medium, image forming apparatus, and color reproduction model creating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color reproduction model creating method for obtaining a maximum physical quantity optimum to an image forming material and using the maximum physical quantity optimum to the image forming material, a storage medium for storing a color conversion profile created on the basis of a color reproduction model, and an image forming apparatus mounted with the storage medium. <P>SOLUTION: A color chart to which no pile height limit is placed is formed on recording paper 20, a colorimeter applies colorimetric processing to the color chart to obtain a colorimetric value. The colorimetric value is analyzed to obtain a maximum pile height, a color chart is again formed on the recording paper on the basis of the maximum pile height, the colorimeter applies colorimetric processing to the color chart to obtain a colorimetric value, and a color reproduction model is created on the basis of the colorimetric value. A color conversion profile created on the basis of the color reproduction model is stored on an HDD which the image forming apparatus mounts. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is based on image data input to an image output device, and a method for creating a color reproduction model used for creating a color conversion profile for outputting an image on recording paper, and a color reproduction model. The present invention relates to a storage medium for storing a color conversion profile, an image forming apparatus equipped with the storage medium, and a color reproduction model creation apparatus.

  The image output device is, for example, image data composed of red (R), green (G), and blue (B), cyan (C), magenta (M), yellow (Y), and black (K). When image data composed of colors is input, color conversion that can be reproduced by the image output device is performed, and for example, an image is formed on a recording sheet using an image forming material such as toner or ink composed of CMYK colors. Form as.

  The color conversion is performed using a color conversion profile, and the color conversion profile is created based on a color reproduction model.

  The color reproduction model is a model indicating a range of colors that can be reproduced by the image output apparatus, and is expressed using, for example, saturation on the horizontal axis and lightness on the vertical axis. The color reproduction model is created by measuring a color chart formed by the image output device using a colorimeter.

  Here, in the toner composed of CMYK, the value when the largest amount is output is 100% for each color. The total of the physical amounts of the four color toners is referred to as a pile height amount (Pile Height amount). When this is expressed, when all four colors are output at the maximum, the pile height amount is 400%. If toner is used at a high pile height such that the pile height is close to 400%, color unevenness due to transfer failure or fixing failure to the recording paper, and if the image forming material is ink, the recording paper will absorb the ink sufficiently. Bleeding due to inability to fill.

  For this reason, the pile height is fixedly 400% or less (for example, 280%), and a color chart is created (see Patent Document 1 and Patent Document 2). However, when the pile height amount is not appropriate, the created color reproduction model is inappropriate.

It has also been proposed to prepare a plurality of color charts corresponding to a plurality of pile height amounts in advance and select a color chart based on the designated pile height amount (see Patent Document 3).
JP 2004-58626 A JP 2004-147257 A JP 2004-230826 A

  However, it is difficult to determine an accurate pile height amount with the above-described prior art, and as a result, an appropriate color chart cannot be obtained, and the color reproduction model is distorted.

  In consideration of the above-described facts, the present invention obtains an optimum maximum physical quantity of an image forming material, stores a color reproduction model creation method using the optimum maximum physical quantity, and a color conversion profile created based on the color reproduction model. It is an object to obtain a medium, an image forming apparatus equipped with the storage medium, and a color reproduction model creation apparatus.

  The present invention provides a color conversion system that performs color conversion using a color conversion profile prepared in advance in an image output device when an image is output to a predetermined medium based on image data input to the image output device. A color reproduction model creating method for creating a color reproduction model that is a basis for creating the color conversion profile, wherein a plurality of physical quantities depending on density are known in advance by the image output device. A color chart composed of color patches is output, each color patch of the output color chart is measured, and the contour of the color reproduction model is less than a predetermined distortion amount based on the color measurement result. In addition, a maximum physical quantity of each color is determined, and the color reproduction model is created using the determined maximum physical quantity as a threshold value.

  According to the present invention, the image output device outputs a color chart, measures the color with a colorimeter, for example, and determines the maximum physical quantity of each color for which the color reproduction model is equal to or less than a predetermined distortion amount based on the color measurement result. decide. The physical quantity is, for example, area instruction data or gradation data, and represents 8-bit (0 to 255) digital data (Cin). Then, a color reproduction model is created based on the determined maximum physical quantity. Therefore, the distortion of the color reproduction model can be eliminated.

  Further, in the present invention, based on the determined maximum physical quantity, the image output device again outputs a color chart, and based on the colorimetric values of each color patch of the output color chart, It is characterized by creating a reproduction model.

  The image output device outputs the color chart again based on the determined maximum physical quantity. Then, each color patch of the color chart is measured, and a color reproduction model is created based on the measured color value. Thereby, the accuracy of the color reproduction model can be increased.

  Further, the present invention is characterized in that a color reproduction model is created by extracting the remaining color patches excluding the color patches exceeding the determined maximum physical quantity.

  A color reproduction model without distortion can be created by extracting the remaining color patches from which the color patches exceeding the determined maximum physical quantity are excluded and creating a color reproduction model.

  In the present invention, the color chart is provided with a plurality of color patches having the same physical quantity, and the number is increased as the physical quantity increases.

  By providing a plurality of color patches having the same physical quantity in the color chart, the accuracy of the colorimetric value can be improved, and the accuracy of the maximum physical quantity can be improved by increasing the number of color patches as the physical quantity increases.

  Furthermore, in the present invention, the physical quantity in which the maximum physical quantity is a variation in colorimetric values of color patches having the same physical quantity, saturation of a change in colorimetric value with an increase in physical quantity, or a reversal of a slope of a change in colorimetric value with an increase in physical quantity It is characterized by determining on the basis of.

  The maximum physical quantity is determined on the basis of the physical quantity in which the variation in the colorimetric value, the saturation of the colorimetric value change, and the inversion of the slope of the colorimetric value change have occurred. For this reason, the standard for determining the maximum physical quantity can be clarified, and the maximum physical quantity can be uniquely determined.

  In the present invention, the physical quantity that is the starting point of the variation, saturation, and inversion is determined based on the physical quantities generated by the colorimetric values of the unit color patch of the three primary colors and the mixed color patch in which the three primary colors are mixed. It is characterized by doing.

  A physical quantity that is the starting point of variation, saturation, and inversion is determined from the colorimetric values of the unit color patch of the three primary colors and the mixed color patch in which the three primary colors are mixed. Accordingly, the maximum physical quantity can be determined from various colors based on, for example, cyan, magenta, and yellow constituting the three primary colors.

  Furthermore, in the present invention, the maximum physical quantity is corrected by a combination of three primary colors forming the color patch.

  By correcting the determined maximum physical quantity by the combination of the three primary colors, the corrected maximum physical quantity can be given to a different color depending on the combination of the three primary colors even if the physical quantity is the same.

  In the present invention, the combination of the three primary colors is determined by at least one of saturation and a ratio of each color.

  The combination of the three primary colors is determined by at least one of saturation and the ratio of each color, and the maximum physical quantity is corrected based on the determination. Therefore, the correction of the maximum physical quantity is performed for colors having the same maximum physical quantity but having different saturation and ratio of each color.

  Furthermore, in the present invention, the image output device is an image forming device that forms an image on a predetermined recording sheet by toner development, and the maximum physical quantity is area ratio instruction data or gradation data.

  When the image output device is an image forming device that forms an image on recording paper by toner development and the maximum physical quantity corresponds to the toner amount, color reproduction based on the maximum physical quantity is used when forming an image on recording paper by toner development. A color conversion profile created by the model can be used.

  The present invention is a storage medium for storing the color conversion profile created based on the color reproduction model created in claims 1 to 8.

  The color conversion profile created based on the color reproduction model is stored in a storage medium, so that when the image is output to a predetermined medium based on the image data, the color conversion profile is appropriately read from the storage medium and used. be able to.

  Furthermore, the present invention is an image forming apparatus equipped with a storage medium for storing the color conversion profile created based on the color reproduction model created in claims 1 to 8.

  When the image forming apparatus is equipped with a storage medium for storing the color conversion profile, the image forming apparatus can perform color conversion on the input image data using the color conversion profile and output an image on a recording sheet.

  The present invention also provides a color reproduction model creation for creating a color reproduction model in a color conversion system that performs color conversion when outputting an image to a predetermined medium based on image data input to an image output device. A method for outputting a color chart composed of a plurality of color patches whose physical quantities depending on density are known in advance by the image output device, and measuring each color patch of the output color chart Then, based on the color measurement result, the maximum physical quantity of each color is determined so that the contour of the color reproduction model is equal to or less than a predetermined distortion amount, and the color reproduction is performed using the determined maximum physical quantity as a threshold value. It is characterized by creating a model.

  According to the present invention, it is possible to eliminate distortion of the color reproduction model of the color conversion system used when outputting an image to a predetermined medium based on image data input to the image output apparatus.

  Furthermore, the present invention provides a color reproduction model creation for creating a color reproduction model in a color conversion system that performs color conversion when outputting an image to a predetermined medium based on image data input to an image output device. An output means for outputting a color chart composed of a plurality of color patches whose physical quantities depending on density are known in advance by the image output device, and each color patch of the output color chart A color measurement means for measuring the color, a determination means for determining the maximum physical quantity of each color based on the color measurement result, so that the contour of the color reproduction model is equal to or less than a predetermined distortion amount, and the determined maximum Creating means for creating the color reproduction model using a physical quantity as a threshold value.

  According to the present invention, the color chart is output by the output means, the color measurement is performed by the color measurement means, and the maximum physical quantity of each color for which the color reproduction model is equal to or less than the predetermined distortion amount by the determination means based on the color measurement result decide. Then, the creating means creates a color reproduction model based on the determined maximum output physical quantity. Therefore, the distortion of the color reproduction model can be eliminated.

  As described above, in the present invention, an optimum maximum physical quantity of an image forming material is obtained, a color reproduction model creation method using the optimum maximum physical quantity, and a storage medium for storing a color conversion profile created based on the color reproduction model The present invention has an excellent effect of obtaining an image forming apparatus and a color reproduction model creating apparatus equipped with the storage medium.

(First embodiment)
FIG. 1 shows an image output system 10 according to the present embodiment.

  The image output system 10 is configured by connecting an image forming apparatus 12, a colorimeter 14, and a personal computer 16 via a network 18.

  The image forming apparatus 12 forms an image on a recording sheet 20 that is a predetermined medium based on image data by toner development.

The colorimeter 14 measures the color of the recording paper 20 output from the image forming apparatus 12, and displays various color systems such as L ^* a ^* b ^* color system and L ^* C ^* h color system. It is expressed as a colorimetric value digitized based on Colorimetric values obtained by colorimetry are transmitted to the personal computer 16 via the network 18. Further, the colorimeter 14 is not connected to the personal computer 16 using the network 18 but may be connected by, for example, RS-232C or USB (Universal Serial Bus).

  The personal computer 16 processes the colorimetric values obtained by the colorimeter, and transmits the processing results and image data to the image forming apparatus 12 via the network 18.

  FIG. 2 is a block diagram showing a main part of control between the image forming apparatus 12 and the personal computer 16.

  The image forming apparatus 12 includes a microcomputer 100.

  The microcomputer 100 controls the image forming apparatus 12 and is connected to a module control unit 104, a network interface 106, and an HDD 108 serving as a storage medium via a bus 102 such as a control bus or a data bus.

  The module control unit 104 is based on a control signal from the microcomputer 100, and a scanner module 110 that reads an image written on a document as image data and a printer that forms image data on the recording paper 20 using toner. The module 112 is controlled.

  The network interface 106 is connected to the personal computer 16 via the network 18.

  The HDD 108 stores image data read by the scanner module 110, image data transmitted from the personal computer 16, and the like.

  The personal computer 16 includes a CPU 200. The CPU 200 performs calculation processing on various input data, and is connected to the ROM 204, RAM 206, HDD 208, and network interface 210 via the bus 202.

  In accordance with the processing of the CPU 200, the ROM 204 reads a program, and the RAM 206 reads and writes data and programs.

  The HDD 208 stores image data created by the personal computer 16 and various other data.

  The network interface 210 is connected to the image forming apparatus 12 via the network 18 and transmits / receives data such as image data.

  Here, the image forming apparatus 12 performs color conversion using a color conversion profile created based on a color reproduction model in order to convert image data composed of RGB colors into an image composed of CMYK colors. I do. The color reproduction model is created based on the result of measuring the color chart formed on the recording paper 20 by the image forming apparatus 12 using the colorimeter 14.

  The color chart is composed of a plurality of color patches whose pile height amount, which is a physical amount depending on the toner density, is known. However, when the maximum pile height is not appropriate, a transfer defect or the like occurs in the color patch formed on the recording paper 20. Therefore, the outline of the color reproduction model obtained by measuring the color patch is distorted, and a good color reproduction model cannot be obtained. For this reason, it is necessary to obtain an optimum maximum pile height amount so that the contour of the color reproduction model is equal to or less than a predetermined distortion amount.

  FIG. 3 is a functional block diagram functionally showing details of the CPU 200 of the personal computer 16 that determines the optimum maximum pile height amount.

  The CPU 200 includes a pile height amount determination unit 300, a color reproduction model creation unit 302, and a color conversion profile creation unit 304. Further, the CPU 200 includes a pile height amount setting unit 310, a pile height amount memory 312, a suitability determination unit 314, and a color chart output control unit 316.

  The color reproduction model creation unit 302 receives the colorimetric values transmitted from the colorimeter 14 to the personal computer 16 and creates a color reproduction model. The color reproduction model creation unit 302 is connected to the color conversion profile creation unit 304, and transmits the created color reproduction model to the color conversion profile creation unit 304.

  The color conversion profile creation unit 304 creates a color conversion profile based on the received color reproduction model, and transmits the color conversion profile to the image forming apparatus 12. The color conversion profile transmitted to the image forming apparatus 12 is stored in the HDD 108 installed in the image forming apparatus 12. A ROM (not shown) is not limited to the HDD 108.

  The pile height amount determination unit 300 includes a colorimetric value analysis unit 306 and a maximum amount determination unit 308.

  The colorimetric value analysis unit 306 receives the colorimetric value transmitted from the colorimeter 14 to the personal computer 16 and analyzes it according to a predetermined standard to be described later. Further, the colorimetric value analysis unit 306 is connected to the maximum amount determination unit 308, and transmits the analysis result to the maximum amount determination unit 308.

  The maximum amount determination unit 308 receives the result analyzed by the colorimetric value analysis unit 306 and determines the maximum pile height amount based on the result. The maximum amount determination unit 308 is connected to the suitability determination unit 314.

  The suitability determination unit 314 compares the reference pile height amount read from the pile height amount memory 312 with the maximum pile height amount determined by the maximum amount determination unit 308, and determines whether or not the reference pile height amount is suitable as the maximum pile height amount.

  Here, the reference pile height amount is a pile height amount used when outputting a color chart for determining the maximum pile height amount.

  The suitability determination unit 314 is connected to the color reproduction model creation unit 302 and the pile height amount setting unit 310. When the reference pile height amount is not suitable for the maximum pile height amount, the maximum pile height amount is transmitted to the pile height amount setting unit 310. . On the other hand, when the reference pile height amount is suitable for the maximum pile height amount, the maximum pile height amount (= reference pile height amount) is transmitted to the color reproduction model creation unit 302.

  The pile height amount setting unit 310 has an operation of setting a pile height amount at the time of color reproduction model creation by the color reproduction model creation unit 302. In the initial stage, the reference pile height amount read from the pile height amount memory 312 is color chart output controlled. To the unit 316. At the time of feedback, the suitability determination unit 314 transmits the maximum pile height value input from the maximum amount determination unit 308 to the color chart output control unit 316.

  The color chart output control unit 316 transmits a color chart formation signal for forming a color chart with the pile height amount received from the pile height amount setting unit 310 to the image forming apparatus 12.

  The HDD 208 included in the personal computer 16 includes a color chart data storage unit 318 and stores color chart data that is image data of the color chart.

  The color chart data is stored in the HDD 108 of the image forming apparatus 12 via the color chart output control unit 316 as necessary, and is formed on the recording paper 20 as a color chart.

  As described above, the color chart is composed of a plurality of color patches whose pile height amounts are known.

  FIG. 4 shows the relationship between the pile height amount and the number of color patches, where the vertical axis represents the number of color patches and the horizontal axis represents the pile height amount.

  Here, it is assumed that the pile height amount when the image forming apparatus 12 outputs the maximum amount of toner for all four colors of CMYK is 400%, and the pile height amount when the toner is not output at all is 0%.

  When the pile height amount is 0% to 200%, the number of color patches is two. However, when the pile height amount exceeds 200%, the number of color patches increases as the color patch has a higher pile height amount.

  As described above, the number of color patches is increased as the pile height amount is increased, and the pile height amount is maximized at 400%.

  The numerical values shown in FIG. 4 are examples, and may be different as long as the pile height amount and the color patch have the same relationship as the relationship shown in FIG. Further, an increase in the number of color patches with respect to an increase in the pile height amount may be a non-linear change instead of a linear change.

  The operation of the first embodiment will be described below.

  The analysis of the colorimetric values obtained as a result of measuring the color patches of the color chart formed on the recording paper 20 by the image forming apparatus 12 with the colorimeter 14 will be described.

  The colorimetric value analysis is performed by the colorimetric value analysis unit 306, and the maximum pile height amount is determined based on the analysis result.

  FIGS. 5A to 5C show a method for obtaining a pile height amount as a reference for obtaining the maximum pile height.

In FIG. 5A, the colorimetric values are expressed in the L ^* a ^* b ^* color system, L ^* is omitted, the vertical axis is b ^* (color change is yellow to blue), and the horizontal axis is a ^* ( The variation in colorimetric values obtained from a plurality of color batches having the same pile height amount is shown as a color change from red to green. As an example, the circle indicated by A in FIG. 5A is a variation of 240% pile height, the circle indicated by B in FIG. 5A is a variation of 280% pile height, and is indicated by C in FIG. 5A. Circle represents a variation in pile height of 320%.

  The greater the pile height, the wider the range of colors that can be expressed by the image forming apparatus 12. However, if the variation is larger than expected, there is a possibility that the toner is not stably placed on the recording paper 20 due to transfer failure or the like. The pile height amount in which such variation does not occur becomes a reference for determining the maximum pile height amount.

FIG. 5B shows the pile height amount at which the colorimetric value is saturated, with the vertical axis representing L ^* (lightness) or C ^* (saturation) and the horizontal axis representing the pile height amount.

As indicated by a point D in FIG. 5B, there is a value at which the change in L ^* or C ^* does not occur even when the pile height amount increases. This indicates that even if the toner amount is increased beyond the pile height indicated by the point D in FIG. 5B, no color change occurs. That is, it is saturated. The pile height amount at which this saturation occurs is a reference for determining the maximum pile height amount.

Further, FIG. 5C shows the reversal of the gradient of the colorimetric value change with an increase in the pile height, with the vertical axis representing L ^* or C ^* and the horizontal axis representing the pile height.

As indicated by a point E in FIG. 5C, there is a value that reverses the slope of the change in L ^* or C ^* as the pile height of the toner amount increases. This indicates that the toner is not properly transferred or fixed on the recording paper 20 at the toner amount equal to or higher than the pile height indicated by the point E in FIG. The pile height amount at which the inclination is reversed becomes a reference for determining the maximum pile height amount.

  The pile height amount that is the starting point of these variations, saturation, and reversal is obtained from the pile height amounts generated by the colorimetric values of the unit color patches of the three primary colors (cyan, magenta, yellow) and the mixed color patch in which the three primary colors are mixed. .

  Further, in addition to the above three criteria, if there is an analysis method effective for serving as a criterion for determining the maximum pile height amount, it may be used.

  Next, a process from determining the maximum pile height amount to creating a color reproduction model will be described with reference to the flowchart of FIG.

  In step 400, the image forming apparatus 12 forms a color chart on the recording paper 20. As a pile height amount when forming a color chart, a reference pile height amount (a fixed value between 0% and 400% pile height amount) stored in the pile height amount memory 312 is used.

  Next, in step 402, the colorimeter 14 performs color measurement of the color patches constituting the color chart.

  In step 404, the colorimetric value obtained by the colorimetry by the colorimeter 14 is transmitted to the personal computer 16, and the personal computer 16 receives the colorimetric value.

  In step 406, the colorimetric value analysis unit 306 analyzes the colorimetric value.

  Next, in step 408, the maximum amount determining unit 308 determines the maximum pile height amount from the result of the colorimetric value analysis by the colorimetric value analyzing unit 306.

  Next, in step 409, the suitability determination unit 314 determines whether the reference pile height amount is suitable for the maximum pile height amount determined by the maximum amount determination unit 308. If it is suitable, the determination is affirmative, and the routine proceeds to step 416. On the other hand, if it is determined that it is not suitable, the determination is negative, and the routine proceeds to step 410.

  In step 410, the image forming apparatus 12 forms a color chart on the recording paper 20 using the maximum pile height determined by the pile height determining unit 300 as a threshold value.

  Next, in step 412, the colorimeter 14 performs color measurement of the color patches constituting the color chart formed on the recording paper 20 in step 410.

  Next, in step 414, the colorimeter 14 transmits the color measurement value to the personal computer 16, and the personal computer 16 receives the color measurement value.

  Next, in step 416, when the process proceeds from step 414 to step 416, the color reproduction model creation unit 302 creates a color reproduction model based on the colorimetric values obtained by measuring the color patches in step 412, The color reproduction model creation process ends. When the process proceeds from step 409 to step 416, the color reproduction model creation unit 302 creates a color reproduction model based on the colorimetric values obtained by measuring the color patches in step 402, and the color reproduction model creation process Exit.

  When the color reproduction model is created by the method described with reference to FIG. 6, the color conversion profile creation unit 304 creates a color conversion profile based on the color reproduction model.

  The color conversion profile is transmitted from the personal computer 16 to the image forming apparatus 12 and stored in the HDD 108 installed in the image forming apparatus 12.

  As described above, according to the first embodiment, a color chart in which the pile height amount is not limited is formed on the recording paper 20, the color chart is measured by the colorimeter 14, and the color measurement is performed. Get the value. By analyzing the colorimetric value, the maximum pile height amount is obtained, a color chart is formed again on the recording paper 20 based on the maximum pile height amount, and color measurement is performed, and a color reproduction model is created based on the colorimetric value. The color conversion profile created based on the color reproduction model is stored in the HDD installed in the image forming apparatus 12.

(Second Embodiment)
In the first embodiment, the image forming apparatus 12 forms a color chart on the recording paper 20 twice. However, the second embodiment is characterized in that a color reproduction model is created only by forming a color chart once.

  Here, with reference to FIG. 7, the functional block diagram which showed the detail of CPU200 with which the personal computer 16 with which it concerns on 2nd Embodiment is provided is shown. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description of the configuration is omitted.

  In the second embodiment, the pile height amount determination unit 300 and the color reproduction model creation unit 302 are connected by adding a data extraction unit 500 therebetween. Further, the data extraction unit 500 is connected to the colorimeter 14 and receives the maximum pile height amount determined by the pile height amount determination unit 300 and the colorimetric value from the colorimeter 14.

  Further, the data extraction unit 500 uses the maximum pile height amount determined by the pile height amount determination unit as a threshold value, and the colorimetric values of the remaining color patches excluding the color patches created exceeding the maximum pile height amount, The data is transmitted to the color reproduction model creation unit 302.

  Next, according to the flowchart of FIG. 8, processing until the maximum pile height amount in the second embodiment is determined and a color reproduction model is created will be described. The same steps as those in the flowchart of FIG. 6 according to the first embodiment will be described only before and after the added steps, and the other same steps will be denoted by the same reference numerals and the description thereof will be omitted.

  When the maximum pile height amount of the toner amount is determined in step 408, the process proceeds to step 600.

  In step 600, the data extraction unit 500 extracts colorimetric values of color patches that are equal to or less than the maximum pile height amount, using the maximum pile height amount as a threshold value.

  In step 602, the color reproduction model creation unit 302 creates a color reproduction model based on the colorimetric values of the color patches extracted by the data extraction unit 500, and the color reproduction model creation process is terminated.

  As described above, according to the second embodiment, a color conversion profile can be created only by forming a color chart once, and the time for creating a color conversion profile can be shortened.

(Third embodiment)
Next, a third embodiment according to the present invention will be described.

  The third embodiment is characterized in that the maximum pile height amount is corrected by a combination of three primary colors forming a color patch.

  In the third embodiment, a correction function for correcting the maximum pile height amount is added to the pile height amount determination unit 300 of FIG. 3 according to the first embodiment or FIG. 7 according to the second embodiment.

  FIG. 9A and FIG. 9B show examples of combinations of three primary colors that are determination factors when the maximum pile height amount is corrected.

  FIG. 9A shows that the maximum pile height amount is corrected by saturation for colors having the same pile height amount (for example, 280%) of CMYK toners. In FIG. 9A, as an example, the saturation is standard when the ratio of toner of C, M, Y, and K is 70%. When the ratio of K is high, the saturation is low, and when the ratio of K is high, the saturation is high.

  When the saturation is low, the maximum amount determination unit 308 corrects the maximum pile height amount to be high. By increasing the maximum pile height when the saturation is low, the range of low saturation colors that can be expressed by the image forming apparatus 12 is expanded.

  On the other hand, when the saturation is high, the maximum amount determination unit 308 corrects the maximum pile height amount to be low. This is because a highly saturated color can be expressed even if the maximum pile height is low.

  FIG. 9B shows that the maximum pile height is corrected by the difference in the toner composition ratio in the same pile height (for example, 240%).

  In FIG. 9B, as an example, it is assumed that the toner is transferred in the order of Y, M, and C, and the case where the ratio of the toner of C, M, and Y is 80% is standard.

  When the ratio of the toner amount in the early transfer order is lower than the toner amount in the late transfer order (Y40%, M100%, C100%), a part of the toner with the late transfer order is placed on the toner with the early transfer order. There is a possibility that it is placed, or part of it is placed on the recording paper 20. For this reason, the transfer conditions of the toner with a slow transfer order vary depending on the location, which may cause a fixing failure of the toner and distort the color reproduction model.

  Therefore, if the amount of toner is reduced, the toners are not unnecessarily overlapped, and the possibility that the transfer conditions differ from place to place is reduced. Therefore, the maximum amount determination unit 308 corrects the maximum pile height amount to be low.

  On the other hand, when the ratio of the toner amount in the early transfer order is higher than the toner amount in the late transfer order (in the case of Y100%, M100%, C40%), the toner with the slow transfer order is added to the toner with the fast transfer order. Since all the toner is loaded, the toner transfer condition does not vary depending on the portion, and the toner is stably fixed on the recording paper.

  If the toner can be stably fixed on the recording paper 20, the range of colors that can be reproduced by the image forming apparatus 12 can be expanded without causing distortion in the color reproduction model by increasing the maximum pile height. . Therefore, the maximum amount determination unit 308 corrects the maximum pile height amount to be increased.

(Modification)
In the first to third embodiments, the CPU 200 provided in the personal computer 16 has a function of determining a maximum pile height amount and creating a color reproduction model and a color conversion profile based on the maximum pile height (FIGS. 3 and 3). 7), the microcomputer 100 of the image forming apparatus 12 (see FIG. 2) may have these functions.

  The image forming apparatus 12 receives the colorimetric values obtained by measuring the color chart with the colorimeter 14 via the network 18, RS-232C, or USB, thereby determining the maximum pile height amount without using the personal computer 16. Thus, a color conversion profile can be created from the color reproduction model.

It is the schematic showing an image output system. 1 is a block diagram illustrating a schematic configuration of an image forming apparatus and a personal computer. It is the functional block diagram which showed the detail of CPU of the personal computer based on 1st Embodiment functionally. It is a figure which shows the relationship between the pile height amount and the number of color patches in a color chart. It is a figure which shows the reference | standard of the pile height amount which determines the maximum pile height amount. (A) shows the magnitude of variation in colorimetric values obtained from a plurality of color batches having the same pile height. (B) shows saturation of the colorimetric value change with an increase in the pile height. (C) shows the reversal of the gradient of the colorimetric value change with the increase in the pile height. It is a flowchart which shows the flow of a process until determining the maximum pile height amount based on 1st Embodiment, and producing a color reproduction model. It is the functional block diagram which showed the detail of CPU of the personal computer based on 2nd Embodiment functionally. It is a flowchart which shows the flow of a process until determining the maximum pile height amount and producing a color reproduction model based on 2nd Embodiment. It is a figure which shows the combination of 3 primary colors used as the judgment element in the case of correct | amending the maximum pile height amount based on 3rd Embodiment. (A) is a figure which shows correct | amending by saturation in the color with the same pile height amount. FIG. 7B is a diagram illustrating that correction is performed based on a difference in the toner composition ratio in colors having the same pile height.

Explanation of symbols

10 image output system 12 image forming apparatus (image output apparatus)
14 Colorimeter 16 PC 18 Network 20 Recording paper (predetermined medium)
100 microcomputer 102 bus 104 module control unit 106 network interface 108 HDD (storage medium)
110 Scanner module 112 Printer module 200 CPU
202 Bus 204 ROM
206 RAM
208 HDD
210 Network Interface 300 Pile Height Amount Determination Unit 302 Color Reproduction Model Creation Unit 304 Color Conversion Profile Creation Unit 306 Colorimetric Value Analysis Unit 308 Maximum Amount Determination Unit 310 Pile Height Amount Setting Unit 312 Pile Height Amount Memory 314 Suitability Judgment Unit 316 Color Chart Output Control Unit 318 Color chart data storage unit 500 Data extraction unit

Claims (13)

In the color conversion system for performing color conversion using a color conversion profile prepared in advance in the image output device when outputting an image to a predetermined medium based on image data input to the image output device, the color A color reproduction model creation method for creating a color reproduction model as a basis for creating a conversion profile,
By the image output device, at least a color chart composed of a plurality of color patches whose physical quantities depending on density are known in advance is output,
Measure each color patch of the output color chart,
Based on the color measurement result, the maximum physical quantity of each color is determined so that the contour of the color reproduction model is a predetermined distortion amount or less,
A color reproduction model creation method, wherein the color reproduction model is created using the determined maximum physical quantity as a threshold value. Based on the determined maximum physical quantity, the image output device again outputs a color chart,
2. The color reproduction model creation method according to claim 1, wherein a color reproduction model is created based on the colorimetric values of each color patch of the output color chart.   The color reproduction model creation method according to claim 1, wherein a color reproduction model is created by extracting the remaining color patches excluding the color patches exceeding the determined maximum physical quantity.   4. The color reproduction model according to claim 1, wherein a plurality of color patches having the same physical quantity are provided on the color chart, and the number is increased as the physical quantity increases. How to make.   The maximum physical quantity is determined based on a physical quantity in which a colorimetric value variation of color patches of the same physical quantity, saturation of a colorimetric value change with an increase in physical quantity, and a reversal of a slope of a colorimetric value change with respect to an increase in physical quantity have occurred. The color reproduction model creation method according to any one of claims 1 to 4, wherein:   The physical quantity that is the starting point of the dispersion, saturation, and reversal is determined based on physical quantities that are generated from the respective colorimetric values of the unit color patch of the three primary colors and the mixed color patch in which the three primary colors are mixed. The color reproduction model creation method according to claim 5.   The color reproduction model creation method according to claim 1, wherein the maximum physical quantity is corrected by a combination of three primary colors forming the color patch.   8. The color reproduction model creation method according to claim 7, wherein the combination of the three primary colors is determined by at least one of saturation and a ratio of each color.   4. The image forming apparatus according to claim 1, wherein the image output apparatus is an image forming apparatus that forms an image on a predetermined recording sheet by toner development, and the maximum physical quantity is area ratio instruction data or gradation data. The color reproduction model creation method according to any one of the above.   A storage medium for storing the color conversion profile created based on the color reproduction model created in any one of claims 1 to 8.   An image forming apparatus including a storage medium for storing the color conversion profile created based on the color reproduction model created in claim 1. A color reproduction model creation method for creating a color reproduction model in a color conversion system that performs color conversion when outputting an image to a predetermined medium based on image data input to an image output device,
By the image output device, at least a color chart composed of a plurality of color patches whose physical quantities depending on density are known in advance is output,
Measure each color patch of the output color chart,
Based on the color measurement result, the maximum physical quantity of each color is determined so that the contour of the color reproduction model is a predetermined distortion amount or less,
A color reproduction model creation method, wherein the color reproduction model is created using the determined maximum physical quantity as a threshold value. A color reproduction model creation device for creating a color reproduction model in a color conversion system that performs color conversion when outputting an image to a predetermined medium based on image data input to an image output device,
Output means for outputting a color chart composed of a plurality of color patches whose physical quantities depending on density are known in advance by the image output device;
A colorimetric means for measuring each color patch of the output color chart;
A determining unit that determines a maximum physical quantity of each color based on a colorimetric result so that an outline of the color reproduction model is equal to or less than a predetermined distortion amount;
Creating means for creating the color reproduction model using the determined maximum physical quantity as a threshold;
A color reproduction model creation device comprising:

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