JP2018120579A - Image processing method, printing method, image processing device, and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer negating the need of correction with respect to variations in ink discharge characteristics of each nozzle array.SOLUTION: An image processing method generates printing data for causing a printing system 1 (printer) printing a printing image based on image data to execute printing by repeating path operation in which a nozzle array discharges ink droplets while relatively moving in an X-axis direction (main scanning direction) with respect to a printing medium and forms dots onto the printing medium and feed operation for relatively moving the nozzle array and the printing medium in a sub-scanning direction intersecting with the X-axis direction (main scanning direction). The image processing method includes: a step of applying a plurality of pieces of (first and second halftone processing) halftone processing for generating halftone data determining a formation state of the dots formed by the nozzle array discharging the same color ink to the same area of the image data and performing them; and a step of allocating the generated halftone data to the path operation.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an image processing method, a printing method for performing printing using the image processing method, an image processing apparatus, and a printing apparatus including the image processing apparatus.

A serial type ink jet printer has a path operation for ejecting ink droplets while moving a head in which a nozzle array for ejecting ink droplets is formed in the main scanning direction (main scanning) with respect to the print medium, and a print medium. By alternately repeating a transport operation that moves (sub-scan) in the transport direction (sub-scan direction) that intersects the main scan direction, dots (dot rows) that are aligned in the main scan direction are formed side by side in the transport direction. Form an image on top.
In such an ink jet printer, a method of increasing the number of nozzles has been taken as one method for further increasing the printing speed. Specifically, this is a method of increasing the number of dots formed in one main scan (pass operation) and increasing the printing speed by increasing the number of nozzles per head or arranging a plurality of heads.

  When a plurality of heads are arranged as a single head, if there is a difference in ink ejection characteristics (variations in ink ejection amount or ejection direction) of the individual heads arranged, the size and position of the dots formed will vary, resulting in uneven color. In some cases, the print quality may be affected. On the other hand, Patent Document 1 describes an ink jet recording apparatus (printing apparatus) including a drive waveform generation data correction unit capable of correcting variations in ink discharge amount and discharge timing.

JP 2001-47614 A

  However, in the ink jet recording apparatus described in Patent Document 1, since it is necessary to perform correction in accordance with the ink ejection characteristics of each head, it is necessary to provide drive waveform generation data correction means for each head, which reduces costs. There was a problem that would be an obstacle. In addition, it is necessary to obtain a correction amount according to the ink ejection characteristics of each head, and there is a problem that adjustment takes time.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples or forms.

  Application Example 1 In the image processing method according to this application example, the nozzle group ejects ink droplets while moving relative to the print medium in the main scanning direction to form dots on the print medium; Print data for causing a printing apparatus that prints a print image based on image data to execute printing by repeating a feeding operation for relatively moving the nozzle group and the print medium in the sub-scanning direction intersecting the main scanning direction. A halftone process for generating halftone data for determining a formation state of the dots formed by the nozzle group that ejects ink of the same color, for the same region of the image data. And a step of applying a plurality of steps, and a step of assigning the generated halftone data to the pass operation.

  According to this application example, the step of applying a plurality of halftone processes for generating halftone data for determining the formation state of dots formed by nozzle groups that eject ink of the same color to the same region of image data And assigning the generated halftone data to a pass operation. In other words, each color print image can be formed by using a plurality of halftone data generated separately by applying a plurality of halftone processes to the same area of the image data.

  As a result, for example, in a printing apparatus, when a nozzle group is configured as a single head that arranges a plurality of heads and discharges ink of the same color (hereinafter referred to as a large head to distinguish the individual heads arranged), For all areas, halftone data corresponding to the individual heads constituting the large head can be generated separately, and the entire image area can be printed for each individual head based on the respective halftone data. it can. In other words, by causing individual heads to print over the entire image area, there is no color unevenness (color unevenness is suppressed) based on uniform ink ejection characteristics (not including variations between individual heads). Images can be obtained for each individual head. By superimposing these print images for each head, printing is assigned to each head so that a print image based on the image data is formed (assigned to the pass operation), thereby ejecting ink from each head. Even when the characteristics vary, it is possible to print a print image in which color unevenness is suppressed.

  As a result, in the printing apparatus, it is not necessary to perform correction according to the ink ejection characteristics of the individual heads in order to suppress variations in the ink ejection characteristics between the individual heads. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each head, and there is no need to provide correction means for executing correction of the correction amount obtained for each head.

  Application Example 2 In the image processing method according to the application example, the nozzle group includes a plurality of nozzle groups, and the halftone process includes a halftone process corresponding to each of the plurality of nozzle groups. Features.

  According to this application example, the plurality of halftone processes applied to the same region of the image data include halftone processes corresponding to the plurality of nozzle groups constituting the nozzle group. That is, printing can be performed using halftone data generated separately for each nozzle group.

  As a result, by causing individual nozzle groups to print over the entire image area, there is no color unevenness (color unevenness is suppressed) based on uniform ink ejection characteristics (not including variations among nozzle groups). A print image can be obtained for each nozzle group. By superimposing the print images for each nozzle group, printing is assigned to each nozzle group so that a print image based on the image data is formed (assigned to the pass operation), so that the ink of each nozzle group Even when there is variation in the ejection characteristics, it is possible to print a print image in which color unevenness is suppressed.

  As a result, there is no need to perform corrections corresponding to the ink ejection characteristics of the individual nozzle groups in order to suppress variations in the ink ejection characteristics between the individual nozzle groups. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each nozzle group, and there is no need to provide correction means for executing correction of the correction amount obtained for each nozzle group.

Further, for example, when a group of nozzles having the same or similar ink ejection characteristics is divided into nozzle groups, the entire image area can be printed based on individual halftone data for each nozzle group. For each nozzle group, it is possible to obtain a printed image with little variation between nozzles and no color unevenness (or suppressed color unevenness). In addition, printing is assigned to each nozzle group so that a print image based on the image data is formed by superimposing these print images for each nozzle group (assignment to the pass operation), thereby eliminating color unevenness. A print image (or color unevenness is suppressed) can be printed efficiently.
As the nozzle group, for example, one head chip including a plurality of nozzles processed in the same manufacturing environment and manufacturing conditions can be applied.

  Application Example 3 In the image processing method according to the application example, the halftone process includes a halftone process using a dither method and a halftone process using an error diffusion method.

  According to this application example, the plurality of halftone processes applied to the same region of the image data includes a halftone process using a dither method and a halftone process using an error diffusion method. Therefore, in the formation of printed images of each color, they are generated separately by applying multiple halftone processes such as halftone processing using the dither method and halftone processing using the error diffusion method to the same area of the image data. Printing can be performed using the plurality of halftone data.

  As a result, for example, when the nozzle group is divided into nozzle groups having the same or similar ink ejection characteristics, a print image based on the image data is formed by overlapping the print images formed for each nozzle group. Can be. In addition, a print image for each nozzle group is formed based on different halftone data processed by a plurality of different halftone processes, such as a halftone process using a dither method or a halftone process using an error diffusion method. . Therefore, when print images formed by nozzle groups having different ink ejection characteristics are superimposed on the same area, the same halftone process is performed on the same image data. Compared with the case of forming based on tone data, the difference in ink ejection characteristics between nozzle groups can be dispersed in the image area, so that printing with lower deterioration in print quality can be performed.

  Application Example 4 In the image processing method according to the application example described above, the dither matrix used for the plurality of halftone processes to be applied includes different dither matrices.

  According to this application example, the dither matrices used for the plurality of halftone processes applied to the same region of the image data include different dither matrices. Therefore, for example, the nozzle group is divided into nozzle groups having the same or similar ink ejection characteristics, and a print image based on the image data is formed by overlapping the print images formed for each nozzle group in the same region. In this case, compared with the case where each print image is formed based on the same halftone data generated by halftone processing the same image data using the same dither matrix, Since the difference in the ink ejection characteristics between the nozzle groups can be dispersed in the image area, it is possible to perform printing with further suppressed print quality degradation.

  Application Example 5 In the image processing method according to the application example described above, the error diffusion method used for the plurality of halftone processes to be applied includes different error diffusion methods.

  According to this application example, error diffusion methods used for a plurality of halftone processes applied to the same region of image data include different error diffusion methods. Therefore, for example, the nozzle group is divided into nozzle groups having the same or similar ink ejection characteristics, and a print image based on the image data is formed by overlapping the print images formed for each nozzle group in the same region. In this case, compared with the case where each print image is formed based on the same halftone data generated by halftone processing the same image data using the same error diffusion method. Since the difference in the ink ejection characteristics between the nozzle groups can be dispersed in the image area, it is possible to perform printing while suppressing the deterioration of the print quality.

  Application Example 6 In the image processing method according to the application example described above, the matrix coordinates for developing the determined dot formation state used for the plurality of halftone processes to be applied include different matrix coordinates. It is characterized by.

  According to this application example, different matrix coordinates are included in the coordinates of the matrix that develops the determined dot formation state used for the plurality of halftone processes applied to the same region of the image data. Matrix coordinates are the coordinates of a dot matrix that develops the result of halftone processing, and different matrix coordinates are, for example, matrices obtained by shifting the coordinate axis by a fraction of the dot pitch in the main scanning direction. Coordinates. Therefore, for example, the nozzle group is divided into nozzle groups having the same or similar ink ejection characteristics, and a print image based on the image data is formed by overlapping the print images formed for each nozzle group in the same region. In this case, as compared with the case where each print image is formed based on halftone data obtained by expanding the result of halftone processing based on the same image data to the same matrix coordinates, Printing with higher uniformity of in-plane distribution of ink can be performed.

  Application Example 7 A printing method according to this application example includes a step of generating print data by the image processing method according to the application example, and a step of printing based on the print data.

According to the printing method of this application example, since printing is performed based on the print data generated by the image processing method according to the application example, there are a plurality of ink ejection characteristics that have a difference (variation in ink ejection amount or ejection direction). Even a printing apparatus having a nozzle group (for example, a head) can efficiently print a print image in which color unevenness is suppressed.
As a result, there is no need to make corrections corresponding to the ink ejection characteristics of individual nozzle groups. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each nozzle group, and there is no need to provide correction means for executing correction of the correction amount obtained for each nozzle group.

  Application Example 8 In the image processing apparatus according to this application example, the nozzle group ejects ink droplets while moving relative to the print medium in the main scanning direction to form dots on the print medium; Print data for causing a printing apparatus that prints a print image based on image data to execute printing by repeating a feeding operation for relatively moving the nozzle group and the print medium in the sub-scanning direction intersecting the main scanning direction. A halftone process for generating halftone data for determining the formation state of the dots formed by the nozzle group that ejects ink of the same color, for the same region of the image data. A plurality of halftone processing units that are applied and an allocation unit that allocates the generated halftone data to the pass operation. That.

  According to the image processing apparatus of this application example, a plurality of halftone processes for generating halftone data for determining the formation state of dots formed by nozzle groups that eject ink of the same color are applied to the same region of image data. A halftone processing unit to be performed in this way, and an allocation unit that allocates the generated halftone data to the pass operation. In other words, each color print image can be formed by using a plurality of halftone data generated separately by applying a plurality of halftone processes to the same area of the image data.

  As a result, for example, in a printing apparatus, when a nozzle group is configured as one large head that arranges a plurality of heads and discharges the same color ink, the individual heads that constitute the large head for all areas of the image data are arranged. Corresponding halftone data can be generated separately, and the entire image area can be printed for each individual head based on the respective halftone data. In other words, by causing individual heads to print over the entire image area, there is no color unevenness (color unevenness is suppressed) based on uniform ink ejection characteristics (not including variations between individual heads). Images can be obtained for each individual head. By superimposing these print images for each head, printing is assigned to each head so that a print image based on the image data is formed (assigned to the pass operation), thereby ejecting ink from each head. Even when there is variation in characteristics, it is possible to efficiently print a printed image in which color unevenness is suppressed.

  As a result, in the printing apparatus, it is not necessary to perform correction according to the ink ejection characteristics of the individual heads in order to suppress variations in the ink ejection characteristics between the individual heads. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each head, and there is no need to provide correction means for executing correction of the correction amount obtained for each head.

  Application Example 9 A printing apparatus according to this application example includes the image processing apparatus according to the application example, and a printing unit that performs printing based on the print data generated by the image processing apparatus. .

  According to this application example, even when there is a variation in the ink ejection characteristics of the individual heads constituting the printing unit, color unevenness is suppressed without correction corresponding to the ink ejection characteristics of the individual heads. The printed image can be printed efficiently. That is, in the printing apparatus according to this application example, it is not necessary to obtain a correction amount according to the ink ejection characteristics of each head at the time of manufacture and adjustment, and the correction amount obtained for each head is corrected. Since there is no need to provide the correction means, it can be more easily manufactured or adjusted and provided at a lower cost.

1 is a front view illustrating a configuration of a printing system as a printing apparatus according to a first embodiment. 1 is a block diagram illustrating a configuration of a printing system as a printing apparatus according to a first embodiment. Illustration of basic functions of printer driver in the prior art Schematic diagram showing an example of nozzle arrangement as seen from the bottom of the print head Conceptual diagram showing a matrix of a data space in which halftone data is developed in the conventional halftone processing Explanatory drawing schematically showing an example in which the dot formation position is displaced due to a difference in ink ejection characteristics Schematic diagram showing an example in the case where color shading is visually recognized in an image printed in the prior art Schematic diagram showing an example in the case where color shading is visually recognized in an image printed in the prior art 6 is a flowchart illustrating functions of a printer driver included in the image processing apparatus according to the first embodiment. Conceptual diagram showing matrix coordinates of halftone data corresponding to each nozzle tip 1 is a conceptual diagram illustrating an image printed by a printing apparatus according to a first embodiment. Conceptual diagram showing other examples of matrix coordinates of halftone data corresponding to each nozzle tip Conceptual diagram showing other examples of matrix coordinates of halftone data corresponding to each nozzle tip Conceptual diagram showing other examples of matrix coordinates of halftone data corresponding to each nozzle tip Conceptual diagram showing obtaining a desired print image by superimposing four images printed by four nozzle chips Conceptual diagram showing an example of dot positions formed in four images printed by four nozzle chips Conceptual diagram showing an example of dot positions formed in four images printed by four nozzle chips

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention. In the following drawings, the scale may be different from the actual scale for easy understanding. Further, in the coordinates added to the drawings, the Z-axis direction is the vertical direction, the + Z direction is the upward direction, the X-axis direction is the front-rear direction, the -X direction is the forward direction, the Y-axis direction is the left-right direction, and the + Y direction is the left direction. The XY plane is a horizontal plane.

(Embodiment 1)
FIG. 1 is a front view showing a configuration of a printing system 1 as a “printing apparatus” according to the first embodiment, and FIG. 2 is a block diagram of the same.
The printing system 1 includes a printer 100 and an image processing apparatus 110 connected to the printer 100. The printer 100 is an ink jet printer that prints a desired image on a roll paper 5 as a long “print medium” supplied in a rolled state based on print data received from the image processing apparatus 110. It is.

<Basic configuration of image processing apparatus>
The image processing apparatus 110 includes a printer control unit 111, an input unit 112, a display unit 113, a storage unit 114, and the like, and controls a print job that causes the printer 100 to perform printing. The image processing apparatus 110 is configured using a personal computer as a preferred example.
Software that operates the image processing apparatus 110 includes general image processing application software (hereinafter referred to as an application) that handles image data to be printed, print data for controlling the printer 100 and causing the printer 100 to execute printing. Includes printer driver software to be generated (hereinafter referred to as printer driver).
That is, the image processing apparatus 110 generates print data for causing the printer 100 to print a print image based on the image data.
Note that the printer driver is not limited to an example configured as a functional unit by software, and may be configured by firmware, for example. For example, the firmware is mounted on an SOC (System on Chip) in the image processing apparatus 110.

The printer control unit 111 includes a CPU 115, an ASIC 116, a DSP 117, a memory 118, a printer interface unit (I / F) 119, and the like, and performs centralized management of the entire printing system 1.
The input unit 112 is information input means as a human interface. Specifically, for example, a port to which a keyboard or an information input device is connected.
The display unit 113 is an information display unit (display) as a human interface, and is related to information input from the input unit 112, an image to be printed on the printer 100, and a print job under the control of the printer control unit 111. Information etc. are displayed.
The storage unit 114 is a rewritable storage medium such as a hard disk drive (HDD) or a memory card. The storage unit 114 stores software (a program operated by the printer control unit 111) that operates the image processing apparatus 110, images to be printed, and print jobs. Related information and the like are stored.
The memory 118 is a storage medium that secures an area for storing a program for the CPU 115 to operate, a work area for the operation, and the like, and includes a storage element such as a RAM or an EEPROM.

<Basic configuration of printer 100>
The printer 100 includes a printing unit 10, a moving unit 20, a control unit 30, and the like. The printer 100 that has received the print data from the image processing apparatus 110 controls the printing unit 10 and the moving unit 20 by the control unit 30 to print an image on the roll paper 5 (image formation).
The print data is image formation data obtained by converting image data so that the printer 100 can print the image data using an application and printer driver included in the image processing apparatus 110, and includes a command for controlling the printer 100.
The image data includes, for example, general full color image information or text information obtained by a digital camera or the like.

The printing unit 10 includes a head unit 11, an ink supply unit 12, and the like.
The moving unit 20 includes a main scanning unit 40, a conveyance unit 50, and the like. The main scanning unit 40 includes a carriage 41, a guide shaft 42, a carriage motor (not shown), and the like. The conveyance unit 50 includes a supply unit 51, a storage unit 52, a conveyance roller 53, a platen 55, and the like.

  The head unit 11 includes a print head 13 and a head control unit 14 having a plurality of nozzles (nozzle groups) that discharge printing ink (hereinafter referred to as ink) as ink droplets. The head unit 11 is mounted on the carriage 41 and reciprocates in the main scanning direction along with the carriage 41 moving in the main scanning direction (X-axis direction shown in FIG. 1). While the head unit 11 (printing head 13) moves in the main scanning direction, the ink droplets are ejected onto the roll paper 5 supported by the platen 55 under the control of the control unit 30, thereby forming dots along the main scanning direction. (Raster line) is formed on the roll paper 5.

The ink supply unit 12 includes an ink tank and an ink supply path (not shown) that supplies ink from the ink tank to the print head 13.
As the ink, for example, as an ink set made of a dark ink composition, a four-color ink set obtained by adding black (K) to a three-color ink set of cyan (C), magenta (M), and yellow (Y), etc. There is. Further, for example, eight colors including ink sets such as light cyan (Lc), light magenta (Lm), light yellow (Ly), and light black (Lk) made of a light ink composition in which the density of each color material is lightened. There are ink sets. The ink tank, the ink supply path, and the ink supply path to the nozzle that ejects the same ink are provided independently for each ink.

A piezo method is used as a method for ejecting ink droplets (inkjet method). The piezo method is a method in which a pressure corresponding to a print information signal is applied to ink stored in a pressure chamber by a piezoelectric element (piezo element), and ink droplets are ejected (discharged) from a nozzle communicating with the pressure chamber for printing.
The method for ejecting ink droplets is not limited to this, and other printing methods may be used in which ink is ejected in droplets to form dot groups on a print medium. For example, a system in which ink is continuously ejected in droplets from a nozzle with a strong electric field between the nozzle and the acceleration electrode placed in front of the nozzle, and printing is performed by giving a print information signal from the deflection electrode while the ink droplet is flying, Alternatively, the ink droplets are ejected in accordance with the print information signal without deflecting (electrostatic suction method), the pressure is applied to the ink with a small pump, and the nozzle is mechanically vibrated with a crystal resonator or the like to force For example, a method of ejecting ink droplets, a method of heating and foaming ink with a microelectrode in accordance with a print information signal, and ejecting ink droplets to perform printing (thermal jet method) may be used.

The moving unit 20 (main scanning unit 40, transport unit 50) moves the roll paper 5 relative to the head unit 11 (printing head 13) under the control of the control unit 30.
The guide shaft 42 extends in the main scanning direction and supports the carriage 41 in a slidable contact state, and the carriage motor serves as a drive source for reciprocating the carriage 41 along the guide shaft 42. That is, the main scanning unit 40 (carriage 41, guide shaft 42, carriage motor) moves the carriage 41 (that is, the print head 13) in the main scanning direction along the guide shaft 42 under the control of the control unit 30. Let

The supply unit 51 rotatably supports a reel on which the roll paper 5 is wound in a roll shape, and sends the roll paper 5 to the conveyance path. The storage unit 52 rotatably supports a reel that winds up the roll paper 5, and winds up the roll paper 5 that has been printed from the conveyance path.
The transport roller 53 includes a drive roller that moves the roll paper 5 in the transport direction (Y-axis direction shown in FIG. 1) intersecting the main scanning direction, a driven roller that rotates as the roll paper 5 moves, and the like. 5 is configured to be conveyed from the supply unit 51 to the storage unit 52 via the printing region of the printing unit 10 (the region in which the print head 13 moves on the upper surface of the platen 55).

The control unit 30 includes an interface unit (I / F) 31, a CPU 32, a memory 33, a drive control unit 34, and the like, and controls the printer 100.
The interface unit 31 is connected to the printer interface unit 119 of the image processing apparatus 110 and transmits / receives data between the image processing apparatus 110 and the printer 100. The image processing apparatus 110 and the printer 100 may be directly connected by a cable or the like, or may be indirectly connected via a network or the like. Further, data transmission / reception may be performed between the image processing apparatus 110 and the printer 100 via wireless communication.
The CPU 32 is an arithmetic processing device for controlling the entire printer 100.
The memory 33 is a storage medium that secures an area for storing a program for the CPU 32 to operate, a work area for the operation, and the like, and includes a storage element such as a RAM or an EEPROM.
The CPU 32 controls the printing unit 10 and the moving unit 20 via the drive control unit 34 according to the program stored in the memory 33 and the print data received from the image processing apparatus 110.

The drive control unit 34 controls the drive of the printing unit 10 (head unit 11 and ink supply unit 12) and the moving unit 20 (main scanning unit 40 and transport unit 50) based on the control of the CPU 32. The drive control unit 34 includes a movement control signal generation circuit 35, a discharge control signal generation circuit 36, and a drive signal generation circuit 37.
The movement control signal generation circuit 35 is a circuit that generates a signal for controlling the movement unit 20 (the main scanning unit 40 and the conveyance unit 50) in accordance with an instruction from the CPU 32.
The ejection control signal generation circuit 36 generates a head control signal for selecting a nozzle for ejecting ink, selecting an ejection amount, controlling ejection timing, and the like according to an instruction from the CPU 32 based on the print data. It is.
The drive signal generation circuit 37 is a circuit that generates a basic drive signal including a drive signal for driving the piezoelectric element of the print head 13.
The drive control unit 34 selectively drives the piezoelectric elements corresponding to the respective nozzles based on the head control signal and the basic drive signal.

  With the above configuration, the control unit 30 moves the carriage 41 that supports the print head 13 along the guide shaft 42 with respect to the roll paper 5 supplied to the printing region by the conveyance unit 50 (the supply unit 51 and the conveyance roller 53). A pass operation for ejecting (applying) ink droplets from the print head 13 while moving in the main scanning direction (X-axis direction) and a “sub-scanning direction” that intersects the main scanning direction by the transport unit 50 (transport roller 53). A desired image is formed (printed) on the roll paper 5 by repeating the transport operation (feed operation) for moving the roll paper 5 in the transport direction (+ Y direction).

<Basic functions of the printer driver in the prior art>
FIG. 3 is an explanatory diagram of basic functions of a printer driver in the prior art.
Printing on the roll paper 5 is started when print data is transmitted from the image processing apparatus 110 to the printer 100. The print data is generated by the printer driver.
Hereinafter, print data generation processing in the prior art will be described with reference to FIG.

  The printer driver receives image data from the application, converts it into print data in a format that can be interpreted by the printer 100, and outputs the print data to the printer 100. When converting image data from an application into print data, the printer driver performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, command addition processing, and the like.

The resolution conversion process is a process for converting the image data output from the application into a resolution (printing resolution) when printing on the roll paper 5. For example, when the print resolution is specified as 720 × 720 dpi, the vector format image data received from the application is converted into bitmap format image data having a resolution of 720 × 720 dpi. Each pixel data of the image data after the resolution conversion process is composed of pixels arranged in a matrix. Each pixel has a gradation value of, for example, 256 gradations in the RGB color space. That is, the pixel data after resolution conversion indicates the gradation value of the corresponding pixel.
Pixel data corresponding to one column of pixels arranged in a predetermined direction among pixels arranged in a matrix is called raster data. The predetermined direction in which the pixels corresponding to the raster data are arranged corresponds to the moving direction (main scanning direction) of the print head 13 when printing an image.

The color conversion process is a process for converting RGB data into data in the CMYK color system space. The CMYK colors are cyan (C), magenta (M), yellow (Y), and black (K), and the image data in the CMYK color system space is data corresponding to the ink color that the printer 100 has. Therefore, for example, when the printer 100 uses 10 types of inks of the CMYK color system, the printer driver generates image data in a 10-dimensional space of the CMYK color system based on the RGB data.
This color conversion processing is performed based on a table (color conversion lookup table LUT) in which gradation values of RGB data and gradation values of CMYK color system data are associated with each other. Note that the pixel data after the color conversion processing is, for example, CMYK color system data of 256 gradations represented by the CMYK color system space.

  The halftone process is a process of converting high gradation number (256 gradations) data into gradation number data that can be formed by the printer 100. By this halftone processing, data indicating 256 gradations indicates, for example, 1-bit data indicating 2 gradations (with or without dots) or 4 gradations (without dots, small dots, medium dots, large dots). It is converted into halftone data that determines the dot formation state, such as 2-bit data. Specifically, from the dot generation rate table corresponding to the gradation value (0 to 255) and the dot generation rate, the dot generation rate corresponding to the gradation value (for example, in the case of 4 gradations, no dot, small Pixel data is created so that dots are formed in a dispersed manner using the dither method, error diffusion method, etc. at the obtained generation rate. The Thus, in the halftone process, halftone data for determining the formation state of the dots formed by the nozzle group that ejects the same color ink is generated.

  The rasterization process is a process of rearranging pixel data arranged in a matrix (for example, 1-bit or 2-bit halftone data as described above) according to the dot formation order at the time of printing. In the rasterizing process, the image data constituted by the pixel data (halftone data) after the halftone process is assigned to each pass operation in which the print head 13 (nozzle array) ejects ink droplets while moving in the main scanning. Is included. When the allocation process is completed, the pixel data arranged in a matrix is allocated to the actual nozzles forming each raster line constituting the print image in each pass operation.

The command addition process is a process for adding command data corresponding to the printing method to the rasterized data. The command data includes, for example, transport data related to transport specifications (such as the amount of movement and speed in the transport direction) of the print medium (roll paper 5).
These processes by the printer driver are performed by the ASIC 116 and the DSP 117 (see FIG. 2) under the control of the CPU 115, and the generated print data is transmitted to the printer 100 via the printer interface unit 119 by the print data transmission process. Is done.

<Nozzle row>
FIG. 4 is a schematic diagram illustrating an example of the arrangement of nozzles as viewed from the lower surface of the print head 13.
As shown in FIG. 4, the print head 13 includes six (black ink nozzle row K, cyan ink nozzle row C, magenta ink nozzle row M, magenta ink nozzle row M) in which a plurality of nozzles for discharging ink of each color are arranged side by side. Yellow ink nozzle row Y, gray ink nozzle row LK, light cyan ink nozzle row LC). The nozzle rows 130 are aligned and arranged so as to be parallel to each other at a constant interval (nozzle row pitch) along a direction (X-axis direction) intersecting the transport direction.

The nozzle row 130 is composed of two nozzle chips 131 that extend in the Y-axis direction and are arranged in series. The nozzle chips 131 are aligned at regular intervals (nozzle pitch) along the transport direction (Y-axis direction). There are 200 nozzles # 1 to # 200 arranged side by side.
The nozzle chip 131 is manufactured by a MEMS (Micro Electro Mechanical Systems) manufacturing process using, for example, a silicon wafer as a basic material and applying a semiconductor process. The 200 nozzles included in the nozzle chip 131 have the same ink ejection characteristics, or An approximate “nozzle group” is formed.
In other words, the print head 13 constituting the “nozzle group” is constituted by a plurality of nozzle chips 131 as “nozzle groups”.
In addition, each nozzle is provided with a drive element (piezoelectric element such as the piezo element described above) for driving each nozzle to eject ink droplets.

<Problems in the prior art>
FIG. 5 is a conceptual diagram showing a matrix of a data space in which halftone data is developed in the conventional halftone processing. The 1-bit data and 2-bit data corresponding to the dot formation state described above are developed at the positions indicated by the circles, and rasterization processing (allocation processing) is performed on the data, and halfway from the assigned nozzles. Dots are formed based on the tone data.

FIG. 6 is an explanatory diagram schematically illustrating an example in which there is a difference in ink ejection characteristics between the nozzle chips 131 constituting the nozzle row 130 and the dot formation position is displaced.
In order to simplify the description, the nozzle row 130 that ejects the same color ink is composed of two nozzle chips 131 (nozzle chip 1311 and nozzle chip 1312), and each nozzle chip 131 is composed of eight nozzles. An example will be described.
For example, the eight dot positions formed by the nozzle chip 1312 in the same shot with respect to the eight dot positions formed by the nozzle chip 1311 in one shot (the position indicated by the numeral 1 in FIG. 6) is the number 2 in FIG. As shown in FIG. 5, when the image is shifted by Δx in the X-axis direction (main scanning direction) and Δy in the Y-axis direction (conveying direction), uneven color shading may be visually recognized in the printed image.

FIG. 7 and FIG. 8 are schematic diagrams illustrating an example in the case where uneven color shading is visually recognized in an image printed in the prior art.
In the example shown in FIG. 7, image formation of an area (band) having a width of 2 L corresponding to the length of a row of 8 × 2 = 16 nozzles is completed by one pass operation, The print medium (roll paper 5) is transported in the transport direction (+ Y direction) according to the width 2L, so that the end of the formed band and the end of the band formed by the next pass operation are in contact with each other. The example in the case of printing by repeating the method of forming a band side by side in the direction (Y-axis direction) is shown. For example, when performing solid printing at the maximum density, large dots are formed at all the dot positions 1 and 2 shown in FIG.
In FIG. 7, the relative positions of the nozzle rows 130 by step movement for each feed amount 2L of the print medium (roll paper 5) are shown in an oblique direction so that the nozzle rows 130 do not overlap. That is, in FIG. 7, the nozzle row 130 is depicted as moving in the −Y direction, but actually the print medium (roll paper 5) moves in the + Y direction. Further, the positional relationship of the nozzle row 130 in the X-axis direction has no meaning.

  In such a printing method, as is clear from FIG. 7, a large difference occurs in the dot density in the area surrounded by the broken line, and as a result, uneven color shading is visually recognized in the printed image. . Specifically, the area A shown in FIG. 7 is visually recognized as a black line (dark line) with a high dot density, and the area B is visually recognized as a white line (light line) with a low dot density.

Further, in the example shown in FIG. 8, in order to reduce the black streaks (dark streaks) and the white streaks (light streaks) as described above, the feed amount in the band width (2L) is set to half the feed amount L, and the band An example in which printing is performed so that the boundary area of the image overlaps the band center area is shown. This is a method of forming one image area in two passes. In the first pass operation, printing is performed with half the density in the X-axis direction (main scanning direction), and in the next pass operation, the density is halved. Printing is performed so as to fill the gaps. This printing is performed by assigning the halftone data developed as shown in FIG. 5 to two pass operations by an assignment process.
This method mixes the black streak (dark streak) region with a high dot density and the white streak (light streak) region with a low dot density, thereby reducing color shading, but the broken line shown in FIG. It can be seen that streaks in the X-axis direction are visible as in the C region surrounded by.

When such uneven color shading is visually recognized, for example, by adjusting the discharge timing from the nozzle during the pass operation for the positional deviation of the dots in the X-axis direction (main scanning direction), It is possible to correct dot misalignment. Further, for example, with respect to dot positional deviation in the Y-axis direction (conveyance direction) between different pass operations, the dot positional deviation is corrected by adjusting the transport amount (feed amount) between pass operations. Can do.
However, in these adjustments, it is necessary to evaluate the ink ejection characteristics of the print heads 13 (each individual nozzle chip 131) included in each printer 100 and determine the adjustment amount (correction amount) based on the evaluation result. In addition, the printer 100 needs to include a mechanism (for example, a discharge timing adjustment mechanism for each nozzle chip 131 or a conveyance amount adjustment mechanism for each pass operation) that can reflect each determined adjustment amount (correction amount). was there.

<Image processing>
FIG. 9 is a flowchart illustrating functions of the printer driver provided in the image processing apparatus 110 according to the present embodiment.
In response to the above-described problem, the image processing apparatus 110 performs, as a function unit in the printer driver, halftone processing for generating halftone data for determining the formation state of dots formed by the nozzle group that ejects the same color ink. A halftone processing unit 120 that performs a plurality of applications on the same area and an allocation unit 121 that allocates the generated halftone data to a pass operation.
That is, in the present embodiment, as an image processing method for generating print data, halftone processing for generating halftone data for determining the formation state of dots formed by the nozzle row 130 as a nozzle group that ejects ink of the same color is used. Including a step of applying a plurality of the same to the same area of the image data, and a step of assigning the generated halftone data to the pass operation.

In other words, in the conventional image processing, halftone processing is collectively performed on the same region of image data (target region for generating print data), and the generated halftone data is assigned to the pass operation to print data. In the image processing in this embodiment, a plurality of halftone processes are applied to the same area (target area for generating print data), and the result (a plurality of halftone processes) is generated. Print data is generated by allocating a plurality of halftone data generated corresponding to each of these to a pass operation.
Further, the plurality of halftone processes applied to the same area of the image data are performed as halftone processes corresponding to each of the nozzle chips 131 as the nozzle group constituting the nozzle row 130.
This will be specifically described below.

  First, as the simplest example, an example in which the matrix coordinates of halftone data are changed as a plurality of halftone processes applied to the same region of image data will be described. That is, different matrix coordinates are included in the coordinates of the matrix (the matrix coordinates of the halftone data) for developing the determined dot formation state used for a plurality of halftone processes applied to the same area of the image data. . In printing, a method of forming one image region in two passes is used, as in the method shown in FIG. That is, printing with half the density in the X-axis direction (main scanning direction) is performed in the first pass operation, the print medium (roll paper 5) is transported with the feed amount L, and the density is halved in the next pass operation. Print to fill the part.

FIG. 10 is a conceptual diagram showing matrix coordinates of halftone data corresponding to each of the nozzle chips 131 (nozzle chip 1311 and nozzle chip 1312).
Halftone processing corresponding to the nozzle chip 1311 (hereinafter referred to as first halftone processing) is a density in the X-axis direction (main scanning direction) in matrix coordinates as compared to the halftone data processing in the prior art shown in FIG. The halftone data is expanded so that is half.
In addition, halftone processing (hereinafter referred to as second halftone processing) corresponding to the nozzle chip 1312 is halftone so that the density in the X-axis direction (main scanning direction) is halved in the same manner as the first halftone processing. As shown in FIG. 10, the data is developed so that the developed coordinate position becomes a coordinate position that fills the gap portion of the coordinate developed by the first halftone process and having the density reduced by half.

  As shown in FIG. 9, the halftone processing unit 120 as a function unit of the printer driver performs such a plurality of halftone processing (first halftone processing and second halftone processing) on the entire area of the image data. (That is, a plurality of halftone processes are applied to the same area of the image data), and a plurality of halftone data (for the first halftone data and the second halftone process corresponding to the first halftone process) Corresponding second halftone data) is obtained.

The allocating unit 121 merges the first halftone data and the second halftone data, performs a rasterizing process including an allocating process to each pass operation of the nozzle chip 1311 and the nozzle chip 1312, and a command adding process to print data. Generate.
In printing, the printer driver transmits print data to the printer 100, the nozzle chip 1311 performs printing in accordance with the print data assigned based on the first halftone data, and the nozzle chip 1312 converts the second halftone data. Printing is performed according to the print data assigned based on the data.
In other words, the allocation unit 121 as a functional unit of the printer driver performs allocation for each pass of the nozzle chip 1311 based on the first halftone data so as to correspond to such two-pass printing, and the nozzle chip Print data is generated by allocating each of the 1312 passes based on the second halftone data.

FIG. 11 is a conceptual diagram showing an image printed by the printing apparatus (printing system 1) according to the present embodiment.
In FIG. 11, the dot indicated by the numeral 1 is a dot formed by the nozzle chip 1311 based on the first halftone data, and the dot indicated by the numeral 2 is formed by the nozzle chip 1312 based on the second halftone data. The dot is shown.
At each dot position, a dot based on the first halftone data or the second halftone data generated based on the image data (that is, if the halftone data is 2 bits, for example, no dot, small dot) , Medium dots, or large dots).

The printing method in the present embodiment includes a step of generating print data by the above-described image processing method of the present embodiment, and a step of printing based on the print data.
According to the printing method according to the present embodiment, as is apparent from FIG. 11, printing with the same nozzle chip 131 is continuously performed in the Y-axis direction, and thus ink between different nozzle chips 131 in the Y-axis direction. A difference in dot density due to a difference in ejection characteristics is eliminated. As a result, the unevenness in the X-axis direction visually recognized by the above-described prior art is not visually recognized. Alternatively, according to the printing method according to the present embodiment, at least unevenness in the X-axis direction visually recognized by the above-described conventional technique is suppressed.

As described above, according to the image processing method, the printing method, the image processing apparatus, and the printing apparatus according to the present embodiment, the following effects can be obtained.
A halftone process for generating halftone data for determining the formation state of dots formed by the nozzle row 130 that ejects the same color ink is classified into a first halftone process and a second halftone process for the same region of image data. And a step of assigning the generated halftone data to the pass operation. That is, the formation of the print image of each color can be performed using a plurality of halftone data (first halftone data and second halftone data) separately generated for the same area of the image data.

  The plurality of halftone processes applied to the same region of the image data correspond to the first halftone process corresponding to the nozzle chip 1311 constituting the nozzle row 130 and the nozzle chip 1312 constituting the nozzle row 130. Second halftone processing. That is, printing can be performed using the halftone data generated separately for each nozzle chip 131.

  As a result, each nozzle chip 131 (each of the nozzle chip 1311 and the nozzle chip 1312) is made to print over the entire image area, thereby being based on uniform ink ejection characteristics (not including variations among the nozzle chips 131). Thus, a print image having no color unevenness (in which color unevenness is suppressed) can be obtained for each nozzle chip 131 (nozzle chip 1311 and nozzle chip 1312 respectively). By superimposing the print images for each nozzle chip 131, printing is assigned to each nozzle chip 131 so that a print image based on the image data is formed (assigned to the pass operation). Even if the ink ejection characteristics 131 vary, it is possible to print a print image in which color unevenness is suppressed.

  As a result, there is no need to make corrections corresponding to the ink ejection characteristics of the individual nozzle chips 131 in order to suppress variations in the ink ejection characteristics between the individual nozzle chips 131. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each nozzle chip 131, and there is no need to provide correction means for executing correction of the correction amount obtained for each nozzle chip 131.

The nozzle chip 1311 and the nozzle chip 1312 are manufactured by a MEMS manufacturing process using a semiconductor process, and the 200 nozzles included in the nozzle chip 131 form a “nozzle group” having the same or similar ink ejection characteristics. doing.
Therefore, for each nozzle chip 131 (each of the nozzle chip 1311 and the nozzle chip 1312), it is possible to obtain a printed image with little variation between nozzles and no color unevenness (or suppressed color unevenness). In addition, color unevenness is achieved by assigning printing to each nozzle chip 131 so that a print image based on the image data is formed by superimposing the print images for each nozzle chip 131 (assigning to the pass operation). It is possible to efficiently print a print image having no color (or color unevenness is suppressed).

  Further, halftone data (first halftone data and second halftone) determined in each of a plurality of halftone processes (first halftone process and second halftone process) applied to the same region of image data. As shown in FIG. 10, different matrix coordinates are used for the coordinates of the matrix for developing (data). Therefore, compared with the case where each print image is formed based on halftone data obtained by expanding the result of halftone processing based on the same image data to the same matrix coordinates, the surface of the ink is more Printing with high uniformity of internal distribution can be performed.

Further, according to the printing method of the present embodiment, even in a printing system 1 (printing apparatus) having a plurality of nozzle chips 131 having a difference in ink ejection characteristics (variation in ink ejection amount and ejection direction), color unevenness. It is possible to efficiently print a print image in which the image is suppressed.
As a result, there is no need to make corrections corresponding to the ink ejection characteristics of the individual nozzle chips 131. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each nozzle chip 131, and there is no need to provide correction means for executing correction of the correction amount obtained for each nozzle chip 131.

  Further, according to the image processing apparatus 110 of the present embodiment, in the printing system 1 (printing apparatus), in order to suppress variations in ink discharge characteristics between the individual nozzle chips 131, the ink discharge characteristics of the individual nozzle chips 131 are supported. This eliminates the need for correction. That is, there is no need to obtain a correction amount that matches the ink ejection characteristics of each nozzle chip 131, and there is no need to provide correction means for executing correction of the correction amount obtained for each nozzle chip 131.

  Further, according to the printing system 1 (printing apparatus) according to the present embodiment, even when the ink ejection characteristics of the individual nozzle chips 131 constituting the printing unit 10 vary, the ink of the individual nozzle chips 131 is used. A print image in which color unevenness is suppressed can be efficiently printed without performing correction in accordance with the ejection characteristics. That is, in the printing system 1 (printing apparatus) according to the present embodiment, it is not necessary to obtain a correction amount according to the ink ejection characteristics of each nozzle chip 131 at the time of manufacture and adjustment. Since it is not necessary to provide a correction means for executing correction of the obtained correction amount, it is more easily manufactured or adjusted and provided at a lower cost.

  In the present embodiment, as the simplest example, an example in which the matrix coordinates of halftone data are made different as a plurality of halftone processes applied to the same region of image data has been described with reference to FIG. However, in the first pass operation, the density in the X-axis direction (main scanning direction) is printed by half, and the print medium (roll paper 5) is transported by the feed amount L. In the next pass operation, the density is halved. The method of performing printing so as to fill the part is not limited to the pattern example shown in FIG. For example, examples shown in FIGS. 12 to 14 may be used.

12 to 14 are conceptual diagrams showing other examples of matrix coordinates of halftone data corresponding to each of the nozzle chips 131 (nozzle chip 1311 and nozzle chip 1312).
As a method of developing halftone data so that the density in the X-axis direction (main scanning direction) is halved in the matrix coordinates, for example, it is developed in a staggered pattern (checkered flag pattern) as shown in FIG. It may be a method. Alternatively, as shown in FIG. 13 and FIG. 14, a method of developing in a houndstooth pattern (checker flag pattern shape) by 2 dots may be used. Moreover, it is not limited to the range of the example shown in FIG. 10, FIG.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below. Here, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the first embodiment, in the halftone process independently performed for each nozzle chip 131, the dot density is reduced by the number of times of the pass operation (that is, the halftone process with a reduced density is performed), and each pass is performed. Although an example has been described in which halftone data is developed by shifting matrix coordinates so that dot positions to be formed do not overlap, a plurality of different halftone processes performed for each nozzle chip 131 are not limited to this method.

(Modification 1)
The image processing method as the first modification is characterized in that a different dither matrix is included in a dither matrix (dither mask) used for a plurality of applied halftone processes.
That is, different dither matrices are used for the dither matrix used in the first halftone process performed on the nozzle chip 1311 and the dither matrix used in the second halftone process performed on the nozzle chip 1312.

  Note that, depending on the dither matrix to be applied, there may be a concern about the influence (interference fringes or the like) due to mutual interference depending on the print image. Therefore, it is preferable to determine the dither matrix by performing sufficient evaluation beforehand.

  According to this modification, the print image for each nozzle chip 131 is formed based on halftone data developed by different dither matrices. Therefore, compared with the case where the print image by each nozzle chip 131 is formed based on the same halftone data generated by performing the halftone process on the same image data using the same dither matrix, Since the difference in the ink ejection characteristics between the nozzle chips 131 can be dispersed in the image area, it is possible to perform printing while suppressing a decrease in print quality.

(Modification 2)
The image processing method as the second modification is characterized in that the plurality of halftone processes to be applied include a halftone process using a dither method and a halftone process using an error diffusion method.
That is, for example, the first halftone process performed on the nozzle chip 1311 expands the halftone data using the dither method, and the second halftone process performed on the nozzle chip 1312 uses the error diffusion method. Expand halftone data.

  According to this modification, the print image for each nozzle chip 131 is based on different halftone data processed by different halftone processes in the halftone process using the dither method and the halftone process using the error diffusion method. Formed. Therefore, when the print images formed by the nozzle chips 131 having different ink ejection characteristics are superimposed on the same region, the respective print images are generated by performing the same halftone process on the same image data. Compared to the case of forming based on halftone data, the difference in ink ejection characteristics between the nozzle chips 131 can be dispersed in the image region, so that printing with a further reduction in print quality can be performed. it can.

(Modification 3)
The image processing method as the modified example 3 is characterized in that in a plurality of applied halftone processes, halftone data is developed using an error diffusion method, and the error diffusion method used therein includes different error diffusion methods. And
That is, different error diffusion methods are used for the error diffusion method used in the first halftone process performed on the nozzle chip 1311 and the error diffusion method used in the second halftone process performed on the nozzle chip 1312.
In the error diffusion method, when image data is expanded into halftone data by halftone processing, the quantization error when the pixel of interest of the image data is binarized is binarized in the vicinity of the pixel of interest. This is a method of successively binarizing each of these gradation values while diffusing to the gradation value of a non-existing pixel.
Different error diffusion methods include the direction of the pixel to be diffused, the range of the pixel to be diffused, and the quantization when the quantization error is diffused to the gradation value of the pixel that has not been binarized in the vicinity of the target pixel. There is a method in which a threshold value for determining whether or not to diffuse as an error is different.

  According to this modification, a print image for each nozzle chip 131 is formed based on halftone data developed by different error diffusion methods. Therefore, compared with a case where each print image is formed based on the same halftone data generated by performing halftone processing on the same image data using the same error diffusion method, the nozzle chip 131 is used. Since the difference in ink ejection characteristics can be dispersed in the image area, printing with further reduced print quality can be performed.

  Note that by using a plurality of different halftone processes as in the first to third modifications described above, the matrix coordinates for developing the halftone data are not necessarily changed as in the first embodiment described with reference to FIG. Although there is no need to shift, it is preferable to shift the matrix coordinates for developing the halftone data in order to perform printing with high uniformity of the in-plane distribution of the ink.

(Modification 4)
In the first embodiment and the first to third modifications, the example in which the nozzle row 130 is configured by the two nozzle chips 131 has been described. However, the present invention is not limited to this.
For example, the nozzle row 130 may be composed of two nozzles, and a different halftone process may be performed for each nozzle as described above, and printing performed on each may be overlaid. Alternatively, the nozzle row 130 may be constituted by three or more nozzle chips 131.

In FIG. 15, the nozzle row 130 includes four nozzle chips 131 (nozzle chips 1311 to 1314), and a desired print image is obtained by superimposing images to be printed (images G <b> 1 to G <b> 4). It shows conceptually.
FIGS. 16 and 17 show examples of dot positions formed in images (images G1 to G4) to be printed. An image Gn is composed of dots formed at positions indicated by numerals n (n = 1 to 4). That is, the matrix coordinates where the halftone data is developed by the halftone process corresponding to each of the nozzle chips 1311 to 1314 are the matrix coordinates where the numbers are arranged at the positions shown in FIGS. ing. That is, the matrix coordinates for developing the halftone data used for the four halftone processes to be applied include four different matrix coordinates.

  In this way, by expanding the halftone data to different matrix coordinates, each print image is converted to halftone data obtained by expanding the result of the halftone processing based on the same image data to the same matrix coordinates. Compared to the case where the ink is formed on the basis, printing with higher uniformity of the in-plane distribution of the ink can be performed.

  DESCRIPTION OF SYMBOLS 1 ... Printing system, 5 ... Roll paper, 10 ... Printing part, 11 ... Head unit, 12 ... Ink supply part, 13 ... Print head, 14 ... Head control part, 20 ... Moving part, 30 ... Control part, 31 ... Interface 32: CPU, 33: Memory, 34: Drive control unit, 35: Movement control signal generation circuit, 36: Discharge control signal generation circuit, 37 ... Drive signal generation circuit, 40 ... Main scanning unit, 41 ... Carriage, 42 DESCRIPTION OF SYMBOLS ... Guide shaft, 50 ... Conveyance part, 51 ... Supply part, 52 ... Storage part, 53 ... Conveyance roller, 55 ... Platen, 100 ... Printer, 110 ... Image processing apparatus, 111 ... Printer control part, 112 ... Input part, 113 Display unit 114 Storage unit 115 CPU ASIC 117 DSP 118 Memory 119 Printer interface 120 Futon processing unit, 121 ... allocation unit, 130 ... nozzle array, 131 ... nozzle tip.

Claims (9)

A nozzle group ejects ink droplets while moving relative to the printing medium in the main scanning direction to form dots on the printing medium, and the nozzle group and the printing medium intersect the main scanning direction. An image processing method for generating print data for causing a printing apparatus that prints a print image based on image data to execute printing by repeating a feeding operation for relative movement in the sub-scanning direction,
Applying a plurality of halftone processes for generating halftone data for determining the formation state of the dots formed by the nozzle group that ejects the same color ink to the same region of the image data; and
Assigning the generated halftone data to the pass operation. An image processing method comprising: The nozzle group includes a plurality of nozzle groups,
The image processing method according to claim 1, wherein the halftone processing includes halftone processing corresponding to each of the plurality of nozzle groups.   The image processing method according to claim 1, wherein the halftone process includes a halftone process using a dither method and a halftone process using an error diffusion method.   The image processing method according to any one of claims 1 to 3, wherein the dither matrix used for the halftone process includes a different dither matrix.   The image processing method according to any one of claims 1 to 4, wherein the error diffusion method used for the halftone process includes a different error diffusion method.   6. The matrix coordinates for developing the determined dot formation state used for the halftone process include different matrix coordinates. 6. Image processing method. A step of generating print data by the image processing method according to claim 1;
And a step of printing based on the print data. A nozzle group ejects ink droplets while moving relative to the printing medium in the main scanning direction to form dots on the printing medium, and the nozzle group and the printing medium intersect the main scanning direction. An image processing apparatus that generates print data for causing a printing apparatus that prints a print image based on image data to execute printing by repeating a feeding operation that relatively moves in the sub-scanning direction.
A halftone processing unit that applies a plurality of halftone processes for generating halftone data for determining the formation state of the dots formed by the nozzle group that ejects the same color ink to the same area of the image data; ,
An image processing apparatus comprising: an allocation unit that allocates the generated halftone data to the pass operation. An image processing apparatus according to claim 8,
A printing unit configured to print based on the print data generated by the image processing apparatus.

Images