JP6848383B2 - Image processing equipment, printing equipment, and computer programs - Google Patents

Description

The present invention relates to a halftone processing technique.

Printing that forms an image consisting of a large number of dots on the print medium by moving the print head having a large number of nozzles for ejecting ink in the main scanning direction and transporting the print medium in the transport direction intersecting the main scanning direction. The device is known. In such a printing apparatus, dot data indicating the image data of multi-gradation ink colors by turning on / off the dots of each ink color is generated. Such dot data is generated using a so-called halftone technique. For example, in the dither method, which is one of the halftone technologies, the gradation value of each pixel is compared with the threshold value set in the dither mask, and when the gradation value is larger than the threshold value, the dots are turned on and the gradation is set. Dot data is generated by performing a binarization process in which dots are turned off when the value is smaller than the threshold value. In such a printing device, there is a problem that the landing position of the ink droplets deviates from the planned position due to the variation of the ink ejection amount for each nozzle and the variation of the flight direction of the ink droplets, and the graininess of the printed image is lowered. Can occur. Patent Document 1 discloses a method for generating a dither mask that can improve the graininess of a printed image even if the landing position of ink droplets shifts.

JP-A-2015-192214

However, even when printing is performed using the dither mask generated by the method described in Patent Document 1, if the landing position of the ink droplets shifts, the graininess (image quality) of the entire printed surface may deteriorate. .. Therefore, there is a demand for a technique for suppressing deterioration of the image quality of the entire printed surface when the landing position of the ink droplet is displaced.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, dot data indicating the presence or absence of ink dots on a medium in a printing apparatus using image data represented by gradation values and a threshold value set in a dither mask. An image processing apparatus including a dot data generation unit for generating an image is provided. This image processing apparatus has, as the dither mask, a first dither mask and a second dither mask different from the first dither mask; the first dither mask and the second dither mask are respectively. When printing is performed by the printing apparatus based on the dot data generated by using the dither mask, the graininess when the first dither mask is used when the amount of landing deviation of the ink in the medium is zero. Is higher than the granularity when the second dither mask is used; within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus. The graininess when the second dither mask is used is set so that there is a higher landing deviation amount range than the graininess when the first dither mask is used; the dot data generator is set. , The threshold value set in the first dither mask in the first region having a plurality of pixels in the first direction and the second direction intersecting the first direction in the image region indicated by the image data. Is used to generate the dot data of the first region; a plurality of pixels in the image region, which are different from the first region and are in the first direction and the second direction, respectively. In the second region having the above, the dot data of the second region is generated using the threshold value set in the second dither mask.

According to the image processing apparatus of this form, the first dither mask and the second dither mask have a landing deviation amount when printing is performed by the printing apparatus based on the dot data generated by the respective dither masks. When it is zero, the granularity when the first dither mask is used is higher than the granularity when the second dither mask is used, the amount of landing deviation is larger than zero, and the maximum expected in the printing apparatus. Within the assumed landing deviation amount range smaller than the deviation amount, there is a landing deviation amount range in which the granularity when the second dither mask is used is higher than the granularity when the first dither mask is used. Since each is set, the dot data of the first region is generated using the threshold set in the first dither mask, and the dot data of the second region is generated using the threshold set in the second dither mask. , Compared to the case where printing is performed based on the dot data generated using only the first dither mask, when the landing deviation amount is within the assumed landing deviation amount range, the printed surface is displaced. It is possible to suppress a decrease in graininess (image quality) as a whole.

(2) According to another embodiment of the present invention, dots indicating the presence or absence of ink dots on a medium in a printing apparatus are used by using image data represented by gradation values and a threshold value set in a dither mask. An image processing apparatus including a dot data generation unit for generating data is provided. In this image processing apparatus, the dither mask includes a first dither mask portion and a second dither mask portion; the first dither mask portion includes a first direction of an image region indicated by the image data. , The second direction intersecting with the first direction is applied to a first region having a plurality of pixels, respectively; the second dither mask portion is the same as the first region of the image region. It is used by applying it to a second region having a plurality of pixels in the first direction and the second direction, which are different regions; the first dither mask portion is one of the first dither masks. The second dither mask portion is configured as a part of a second dither mask different from the first dither mask; the first dither mask and the second dither mask are The first dither mask was used when the amount of landing deviation of the ink in the medium was zero when printing was performed by the printing apparatus based on the dot data generated by using each dither mask. The graininess of the case is higher than that of the case where the second dither mask is used; the estimated landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus. Within the range, the graininess when the second dither mask is used is set so that there is a higher landing deviation amount range than the graininess when the first dither mask is used. ..

According to the image processing apparatus of this form, the dither mask includes a first dither mask portion formed as a part of the first dither mask and a second dither mask portion formed as a part of the second dither mask. And, when printing is performed by the printing apparatus based on the dot data generated by using the first dither mask and the second dither mask, the first is the case where the landing deviation amount is zero. Assuming that the granularity when the original dither mask is used is higher than the granularity when the second dither mask is used, the amount of landing deviation is larger than zero, and the amount of impact deviation is smaller than the maximum amount of deviation assumed in the printing apparatus. Within the landing deviation amount range, the graininess when the second dither mask is used is set so that there is a higher landing deviation amount range than the granularity when the first dither mask is used. Therefore, the dot data of the first region is generated by using the threshold value set in the first dither mask portion, and the dot data of the second region is generated by using the threshold value set in the second dither mask portion. 1 When printing is performed based on the dot data generated using the threshold set only for the dither mask, and the landing position shift occurs so that the landing deviation amount is within the assumed landing deviation amount range. In the above, deterioration of graininess (image quality) of the entire printed surface can be suppressed.

In addition, since a single dither mask including the first dither mask portion and the second dither mask portion is used, the storage area of the dither mask can be reduced in the image processing apparatus. Further, as compared with the configuration having the first dither mask and the second dither mask as the dither mask, the process of selecting which of the first dither mask and the second dither mask to use can be omitted. , The time required for the process of generating dot data can be shortened.

(3) In the image processing apparatus of the above embodiment, the first region is a single unit region in the image region, which is a unit region including a plurality of the first regions and a plurality of the second regions. The second region may have a single polygonal shape. According to the image processing apparatus of this form, since the first region and the second region each have a single polygonal shape in the unit region, the boundary line between the first region and the second region is a straight line. The first region and the second region can be arranged so as not to form a shape, and the boundary line that is not parallel to at least one of the first direction and the second direction can be made inconspicuous in the printed image.

(4) In the image processing apparatus of the above embodiment, the boundary line between the first region and the second region may intersect at least one of the first direction and the second direction. According to the image processing apparatus of this form, the boundary line between the first region and the second region is not parallel to at least one of the first direction and the second direction. Therefore, in the printed image, the first direction and the second direction are used. Borders that are not parallel to at least one of the directions can be made less noticeable.

(5) In the image processing apparatus of the above-described embodiment, the first region and the second region may have different shapes from each other. According to the image processing apparatus of this form, since the first region and the second region have different shapes, it is possible to prevent the boundary line between the first region and the second region from becoming linear. The boundary line between the first region and the second region can be made inconspicuous in the printed image.

(6) In the image processing apparatus of the above embodiment, the boundary line between the first region and the second region is a plurality of parallel portions parallel to either one of the first direction and the second direction. It may have a plurality of parallel portions that are not in contact with each other. According to the image processing apparatus of this form, since the plurality of parallel portions are not in contact with each other, the boundary line between the first region and the second region can be made inconspicuous in the printed image.

(7) In the image processing apparatus of the above embodiment, in the unit region in the image region, which is a unit region including the plurality of the first region and the plurality of the second regions, the first region and the second region. The region may be a part of the region that overlaps with each other. According to the image processing apparatus of this form, since the first region and the second region overlap each other in a part of the unit region, the boundary line between the first region and the second region is not conspicuous in the printed image. it can.

The present invention can also be realized in various forms. For example, it can be realized in the form of an image processing method, a printing device, a printing method, a computer program for realizing these devices and methods, a recording medium on which such a computer program is recorded, and the like.

The plurality of components of each form of the present invention described above are not all essential, and may be used to solve some or all of the above-mentioned problems, or part or all of the effects described herein. In order to achieve the above, it is possible to change, delete, replace some of the plurality of components with new other components, and partially delete the limited contents, as appropriate. In addition, in order to solve a part or all of the above-mentioned problems, or to achieve a part or all of the effects described in the present specification, the technical features included in the above-mentioned embodiment of the present invention. It is also possible to combine some or all with some or all of the technical features contained in the other embodiments of the invention described above to form an independent embodiment of the invention.

It is a block diagram which shows the structure of the image processing apparatus as one Embodiment of this invention. It is explanatory drawing which shows the schematic structure of the printing apparatus. It is explanatory drawing which shows typically the change of the graininess with respect to the landing deviation amount at the time of printing based on the dot data generated by using the 1st dither mask and the 2nd dither mask independently. It is a flowchart which shows the processing procedure of the printing process executed by an image processing apparatus and a printing apparatus. It is a flowchart which shows the detailed procedure of the halftone processing (step S110) of one color component of four ink colors C, M, Y, K. It is explanatory drawing which shows typically the mode that the dither mask is applied to the image area indicated by the image data. It is explanatory drawing which shows in a schematic form by enlarging the minimum unit area shown in FIG. It is explanatory drawing which shows an example of the mask selection map. It is a block diagram which shows the schematic structure of the image processing apparatus in 2nd Embodiment. It is explanatory drawing which shows typically the structure of the dither mask in 2nd Embodiment. It is a flowchart which shows the detailed procedure of the halftone processing (step S110) in 2nd Embodiment. An explanatory diagram schematically showing a change in graininess with respect to the amount of landing deviation when printing is performed based on dot data generated by using the first dither mask and the second dither mask independently in the first modification. is there. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 1st aspect in the modification 2. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 2nd aspect in the modification 2. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 3rd aspect in the modification 2. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 1st aspect in the modification 3. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 2nd aspect in the modification 3. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 3rd aspect in the modification 3. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 1st aspect in the modification 4. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 2nd aspect in the modification 4. It is explanatory drawing which shows the structure of the 1st region and the 2nd region of the 3rd aspect in a modification 4. It is explanatory drawing which shows the structure of the 1st region and the 2nd region in the modification 5. It is explanatory drawing which shows the structure of the 1st region and 2nd region in the modification 6.

A. First Embodiment:
A1. Image processing device configuration:
FIG. 1 is a block diagram showing a configuration of an image processing device 100 as an embodiment of the present invention. The image processing device 100 performs image processing of the image printed by the printing device 200, and transmits the image data for printing after the image processing to the printing device 200. The image processing device 100 is configured to be able to communicate with the printing device 200. In the present embodiment, the image processing device 100 is composed of a personal computer. The application 20 and the printer driver 30 are incorporated in the operating system that operates in the image processing device 100.

The printer driver 30 includes a resolution conversion unit 31, a color conversion unit 32, a halftone processing unit 33, and a print data output unit 35.

The resolution conversion unit 31 has a function of converting the resolution of the input image into the print resolution. The input image corresponds to, for example, an image generated by the application 20 or an image received from an input interface (not shown). In the present embodiment, the input image is represented by a gradation value composed of red (R), green (G), and blue (B) color components. In the present embodiment, the gradation value range of the input image is 0 to 255.

The color conversion unit 32 has a function of converting the image data of the input image into the image data represented by the gradation values of the ink colors C, M, Y, and K. In the present embodiment, the gradation value range of the image data after color conversion is 0 to 255. The gradation value range of the image data is not limited to 0 to 255, and may be any range such as 0 to 128. The color conversion unit 32 performs the above color conversion with reference to the color conversion table 40 stored in the memory 50 in advance.

The halftone processing unit 33 sets the gradation value of 256 gradations (steps) of the image data of each ink color to the presence / absence of dots of each ink color, in other words, 2 with dots (255) and without dots (0). Executes halftone processing that converts to the gradation value of the gradation. In the present embodiment, the halftone processing is performed by the so-called dither method. In the dither method, a plurality of pixels constituting the image data are sequentially specified as the pixel of interest, and the presence or absence of dots in the pixel of interest is determined using the gradation value of the pixel of interest and the threshold value set in the dither mask. ..

In the present embodiment, as the above-mentioned dither mask, the first dither mask 42a and the second dither mask 42b are stored in the memory 50 in advance. The first dither mask 42a and the second dither mask 42b are different dither masks. In the present embodiment, among the image areas indicated by the image data, the dot data of a certain image area (first area Ar1 described later) is generated by using the threshold value set in the first dither mask 42a, and the certain image area. The dot data of (the second region Ar2 described later) is generated by using the threshold value set in the second disaster mask 42b. The mask selection map 41 is stored in the memory 50 in advance. In the mask selection map 41, which of the first dither mask 42a and the second dither mask 42b is used is set for each pixel of the image data. A detailed description of the halftone processing, the mask selection map, and the dither mask will be described later.

The print data output unit 35 rasterizes the data processed by the halftone processing unit 33, that is, the data indicating the presence or absence of dots on the print medium of each ink color C, M, Y, K, and commands for print control. The print data including the above is generated and transmitted to the printing apparatus 200. When rasterizing the dot data, the print data output unit 35 determines whether the dots of each pixel are formed in the forward movement or the double movement of the carriage (not shown) in the printing device 200.

The printer driver 30 corresponds to a computer program for realizing the functions of the above-mentioned processing units 31 to 35. The printer driver 30 is supplied in a form recorded on a computer-readable recording medium. Such recording media include, for example, DVDs, flash memories, computer internal storage devices (memory such as RAM and ROM) and external storage devices, in which data can be fixed rather than temporarily and can be read by a computer. Various media can be used.

A2. Printing device configuration:
FIG. 2 is an explanatory diagram showing a schematic configuration of the printing apparatus 200. The printing device 200 is an inkjet printer that prints an image or the like by forming dots on the printing medium P by ejecting ink based on the image data received from the image processing device 100. The printing device 200 includes a control unit 220, a head unit 230, a carriage motor 240, a transport motor 250, a drive belt 261 and a flexible cable 262, and a platen 263.

The control unit 220 is a device including a CPU, a RAM, and an input / output interface, and the CPU executes a computer program stored in the RAM to control each part of the printing device 200.

The head unit 230 is electrically connected to the control unit 220 via a flexible cable 262. The head unit 230 is attached to a carriage guide (not shown) so as to be reciprocally movable in the main scanning direction D1. The head unit 230 reciprocates along the main scanning direction D1 by the power of the carriage motor 240 transmitted via the drive belt 261.

The head unit 230 includes a carriage 231, four ink cartridges 232, and a print head 233. Four ink cartridges 232 for each ink color are mounted on the carriage 231. In the present embodiment, the four ink cartridges 232 contain cyan (C), magenta (M), yellow (Y), and black (K) inks, respectively. The print head 233 is provided with a plurality of nozzle rows for ejecting ink on the surface facing the print medium P. The ink supplied from the ink cartridge 232 to the print head 233 is ejected in the form of droplets from such nozzles.

The transfer motor 250 is driven in response to a control signal from the control unit 220. By transmitting the power of the transfer motor 250 to the platen 263, the print medium P is transferred in the sub-scanning direction D2.

When the image data of the image to be printed is input from the image processing device 100, the control unit 220 drives the transport motor 250 to transport the print medium P to the print start position in the sub-scanning direction D2. The control unit 220 drives the carriage motor 240 and moves the head unit 230 to the printing start position in the main scanning direction D1. The control unit 220 controls the head unit 230 to move along the main scanning direction D1 and ejects ink from the head unit 230 to the print medium P, and the transport motor 250 for transporting the print medium P in the sub-scanning direction D2. The control of is repeated alternately. As a result, the image is printed on the print medium P. In FIG. 2, the head unit 230 reciprocates along the main scanning direction D1, and the print medium P is conveyed along the upstream to downstream of the sub-scanning direction D2 that intersects the main scanning direction D1. In the present embodiment, the sub-scanning direction D2 is a direction orthogonal to the main scanning direction D1.

A3. Dither mask composition:
FIG. 3 schematically shows a change in graininess with respect to the amount of landing deviation when printing is performed based on dot data generated by using the first dither mask 42a and the second dither mask 42b independently. It is a figure. As will be described later, in the present embodiment, the first dither mask 42a and the second dither mask 42b are used in combination and are not used alone. In FIG. 3, the vertical axis represents graininess and the horizontal axis represents the amount of landing deviation. In FIG. 3, the change in graininess with respect to the amount of landing deviation when printing is performed based on the dot data generated using the first dither mask 42a is represented by a solid line, and the dots generated using the second dither mask 42b are shown. The changes in graininess with respect to the amount of landing deviation when printing is performed based on the data are shown by broken lines.

In the present embodiment, "graininess" means the dispersibility of dots formed on the print medium P. Specifically, a printed image, that is, an image represented by ink dots, is Fourier transformed to obtain a power spectrum, and the obtained power spectrum is used as a sensitivity characteristic (VTF: Visual Transfer Function) for the spatial frequency of human vision. It is an index obtained by integrating at each spatial frequency with a corresponding weight. Such an index is obtained by, for example, the following formula (1).

In the above equation (1), the coefficient K indicates a coefficient for matching the obtained value with the human sense. The VTF in the above formula (1) is obtained by, for example, the following formula (2).

In the above equation (2), the variable L indicates the observation distance, and the variable u indicates the spatial frequency.

In the present embodiment, the “landing deviation amount” means the landing deviation amount of the ink on the print medium P. Specifically, it means the distance between the planned landing position of the ink droplet and the actual landing position on the print medium P. The landing position shift may occur due to, for example, variations in the amount of ink ejected from each nozzle and variations in the flight direction of ink droplets. The gMax shown on the horizontal axis of FIG. 3 indicates the maximum deviation amount (hereinafter, referred to as “maximum deviation amount”) assumed in the printing apparatus 200.

When printing is performed based on the dot data generated by using the first dither mask 42a, the graininess becomes the maximum value when the landing deviation amount is zero, and gradually decreases as the landing deviation amount increases. It is the lowest value when the maximum deviation amount is gMax. This is because when the first dither mask 42a is used, the amount of landing deviation is zero, that is, when the landing deviation does not occur, the dispersibility of the dots in the print medium P is very good, and the amount of landing deviation is large. When the above occurs, it means that the dispersibility of dots in the print medium P deteriorates as the amount of landing deviation increases.

The graininess when printing is performed based on the dot data generated by using the second dither mask 42b is substantially constant within the range of the landing deviation amount from zero to the maximum deviation amount gMax. This is because when the second dither mask 42b is used, the dispersibility of the dots on the print medium P is almost the same regardless of the amount of landing deviation, and the amount of landing deviation is maximum as compared with the case where the amount of landing deviation is zero. It means that the dispersibility of dots can be maintained at the same level as in the case where the amount of deviation is gMax. However, as shown in FIG. 3, when the amount of landing deviation is zero, the graininess when printing is performed based on the dot data generated by using the second dither mask 42b is the first dither mask 42a. It is lower than the graininess when printing is performed based on the dot data generated by using.

Here, as shown in FIG. 3, when the landing deviation amount is between zero and g1, the graininess when the second dither mask 42b is used becomes the graininess when the first dither mask 42a is used. Low compared to. On the other hand, when the landing deviation amount is between g1 and gMax, the graininess when the second dither mask 42b is used is higher than the graininess when the first dither mask 42a is used. In other words, when printing is performed based on the dot data generated by using the second dither mask 42b within the range of the landing deviation amount larger than zero and smaller than the maximum deviation amount gMax. The graininess has a higher landing deviation amount range than the graininess when printing is performed based on the dot data generated by using the first dither mask 42a. Therefore, when the landing deviation amount is within the range from g1 to the maximum deviation amount gMax, the graininess can be increased when the second dither mask 42b is used as compared with the case where the first dither mask 42a is used.

In the present embodiment, the above-mentioned landing deviation amount g1 is a value of about 1/2 of the maximum deviation amount gMax, but is not limited to such a value, and is an arbitrary value larger than zero and smaller than the maximum deviation amount gMax. There may be.

A4. Printing process:
FIG. 4 is a flowchart showing a processing procedure of printing processing executed by the image processing device 100 and the printing device 200. As shown in FIG. 4, when the user specifies a print target image in the image processing device 100 and gives a print instruction, the print process is executed. The resolution conversion unit 31 executes a resolution conversion process on the designated print target image (step S100). Specifically, the resolution conversion unit 31 converts the resolution of the image to be printed into the resolution at the time of printing on the print medium P.

The color conversion unit 32 executes a color conversion process to convert the input image data into image data represented by the gradation value of the ink color (step S105). The color conversion unit 32 converts RGB data into image data having 256 gradations represented by the color space of the ink color CMYK with reference to the color conversion table 40.

The dot data generation unit 34 uses the first dither mask 42a and the second dither mask 42b to execute halftone processing for each color component of each ink color (step S110). The halftone processing is started when the image data of each color component of the ink colors C, M, Y, and K is received from the color conversion unit 32. The details of the halftone processing will be described later.

The print data output unit 35 executes the print data output process using the dot data (step S115). Specifically, the print data output unit 35 executes rasterization processing on the dot data after the halftone processing, and outputs the processed data (print data) to the printing apparatus 200. When the print device 200 receives the print data from the print data output unit 35, the print device 200 prints the print target image on the print medium P according to the control command included in the print data (step S120).

A5. Details of halftone processing:
FIG. 5 is a flowchart showing a detailed procedure of halftone processing (step S110) of one color component of the four ink colors C, M, Y, and K. The detailed procedure of the halftone processing in the present embodiment is outlined below. That is, it is a process of specifying a plurality of pixels constituting the image data as a pixel of interest one by one in a predetermined order, determining on / off of dots for each pixel of interest, and generating dot data. Specifically, it starts from the pixel in the upper left corner of the image data, moves one by one to the right, and when it reaches the right end, it moves to the left end pixel one step down, and pays attention to it in sequence. Pixels are specified, dots are turned on / off for each pixel of interest, and dot data is generated.

As shown in FIG. 5, the dot data generation unit 34 determines whether or not the processing of all pixels of the image data is completed (step S205). At this time, the dot data generation unit 34 determines whether or not the position of the pixel of interest has reached the end of the image data. When the position of the pixel of interest has reached the end of the image data, it is determined that the processing of all pixels has been completed (step S205: YES), and the halftone processing for one color is terminated. When it is determined that the processing of all the pixels is not completed (step S205: NO), the next pixel is specified as the pixel of interest (step S210). After executing step S210, the dot data generation unit 34 refers to the mask selection map 41 and acquires a threshold value from the dither mask corresponding to the pixel of interest (step S215). The details of this step S215 will be described with reference to FIGS. 6 to 8.

FIG. 6 is an explanatory diagram schematically showing how a dither mask is applied to the image region F1 indicated by the image data. As shown in FIG. 6, the image region F1 indicated by the image data is divided into two types of regions, a first region Ar1 and a second region Ar2, from the viewpoint of applying a dither mask. The first area Ar1 and the second area Ar2 are virtual areas indicating which dither mask is applied to determine the presence or absence of dots in each pixel, and the areas are not printed separately in this way. Absent. In the image region F1, the first region Ar1 has a substantially diamond shape. In the image region F1, the second region Ar2 also has a substantially diamond shape. In the image region F1, each first region is arranged so that the vertices of each region are in contact with each other. In the image region F1, each second region is also arranged so that the vertices of each other are in contact with each other. In the image region F1, each first region and each second region are arranged so that one side of each region touches each other. As described above, which dither mask is used in the first region Ar1 and the second region Ar2 is determined by the mask selection map 41.

In the division between the first region Ar1 and the second region Ar2 as shown in FIG. 6, the minimum unit region ArMin composed of four first regions Ar1 and one second region Ar2 is the main scanning direction D1 and sub-scanning. It is realized by repeatedly applying without a gap along the direction D2. As will be described later, the size of this minimum unit region ArMin is equal to the size of the two-dimensional array in the mask selection map 41. Each minimum unit region ArMin is arranged in the image region F1 so that the boundary line of the two minimum unit regions ArMin adjacent to the main scanning direction D1 is parallel to the sub-scanning direction D2 of each minimum unit region ArMin. Further, each minimum unit region ArMin is arranged in the image region F1 so that the boundary line of the two minimum unit regions ArMin adjacent to the sub-scanning direction D2 is parallel to the main scanning direction D1 of each minimum unit region ArMin. There is.

FIG. 7 is an explanatory diagram schematically showing an enlarged minimum unit region ArMin shown in FIG. As shown in FIG. 7, the minimum unit region ArMin is composed of four first regions Ar1 and a second region Ar2. Each first region Ar1 has a plurality of pixels in each of the main scanning direction D1 and the sub-scanning direction D2. The second region Ar2 is a region different from the first region Ar1, and has a plurality of pixels in each of the main scanning direction D1 and the sub-scanning direction D2. Each first region Ar1 has a substantially triangular shape. The second region Ar2 has a substantially rhombus shape. The four first regions Ar1 are arranged around the second region Ar2, and the four first regions Ar1 and the second region Ar2 are in contact with each other at the boundaries L1, L2, L3 and L4. The boundary lines L1 to L4 intersect the main scanning direction D1 and the sub-scanning direction D2, respectively.

FIG. 8 is an explanatory diagram showing an example of the mask selection map 41. FIG. 8 shows values corresponding to some pixels in the main scanning direction D1 and the sub-scanning direction D2 in the mask selection map 41. The mask selection map 41 is a two-dimensional array corresponding to the minimum unit area ArMin. The upper left area shown in the mask selection map 41 corresponds to the first area Ar1 arranged in the upper left in the minimum unit area ArMin. The lower left area shown in the mask selection map 41 corresponds to the first area Ar1 arranged at the lower left in the minimum unit area ArMin. The central region shown in the mask selection map 41 corresponds to the second region Ar2 in the minimum unit region ArMin.

As shown in FIG. 8, 1 is set for each pixel corresponding to the first region Ar1. 2 is stored for each element corresponding to the second region Ar2. In the present embodiment, in step S215, for the pixel for which 1 is set in the mask selection map 41, the threshold value set for the pixel at the same position in the first dither mask 42a is acquired. On the other hand, for the pixels for which 2 is set in the mask selection map 41, the threshold values set for the pixels at the same position in the second dither mask 42b are acquired. Then, by executing the subsequent procedure, in the present embodiment, for the pixel for which 1 is set in the mask selection map 41, dot data is generated using the first dither mask 42a, and 2 is set. For the pixels, dot data is generated using the second dither mask 42b. In other words, of the image area F1 indicated by the image data, the dot data of the first area Ar1 is generated in the first area Ar1 using the threshold value set in the first dither mask 42a, and the dot data of the first area Ar2 is generated in the second area Ar2. 2 Dot data of the second region Ar2 is generated using the threshold value set in the dither mask 42b.

As shown in FIG. 5, after the execution of step S215, the dot data generation unit 34 determines whether or not the gradation value of the pixel of interest is smaller than the threshold value (step S220). When it is determined that the gradation value of the pixel of interest is equal to or greater than the threshold value (step S220: NO), the dot of the pixel of interest is determined to be ON (step S225). At this time, the gradation value of the pixel of interest in the dot data is set to 255. On the other hand, in step S220 described above, when it is determined that the gradation value of the pixel of interest is smaller than the threshold value (step S220: YES), the dot data generation unit 34 determines that the dot of the pixel of interest is OFF (step S220: YES). Step S230). At this time, the gradation value of the pixel of interest in the dot data is set to 0.

After executing step S225 or step S230, the process returns to step S205, and the above steps S205 to S230 are repeatedly executed until the halftone processing for all pixels of the image data for one color is completed. When the halftone processing for the image data for one color is completed, the halftone processing is similarly executed for the image data of the remaining color components.

According to the image processing apparatus 100 of the first embodiment described above, the first dither mask 42a and the second dither mask 42b are printed by the printing apparatus 200 based on the dot data generated by using the respective dither masks. When the amount of landing deviation is zero, the granularity when the first dither mask 42a is used is higher than the granularity when the second dither mask 42b is used, and the amount of landing deviation is large. Within the range of the assumed landing deviation amount larger than zero and smaller than the maximum deviation amount gMax assumed in the printing apparatus 200, the granularity when the second dither mask 42b is used is the case where the first dither mask 42a is used. Each is set so that there is a range of landing deviation amount higher than the granularity, and dot data of the first region Ar1 is generated using the threshold set in the first dither mask 42a to generate the second dither mask. Since the dot data of the second region Ar2 is generated using the threshold value set in 42b, the amount of landing deviation is larger than that in the case of printing based on the dot data generated using only the first dither mask 42a. When the landing position shift occurs within the assumed landing shift amount range, it is possible to suppress the deterioration of the graininess (image quality) of the entire printed surface.

In addition, in the minimum unit region ArMin, the first region Ar1 and the second region Ar2 have a single polygonal shape different from each other. Therefore, the first region and the second region can be arranged so that the boundary line between the first region and the second region does not become linear, and the boundary line between the first region Ar1 and the second region Ar2 is both. It intersects the main scanning direction D1 and the sub-scanning direction D2. Therefore, in the printed image, the boundary line between the first region and the second region can be made inconspicuous.

B. Second embodiment:
B1. Image processing device configuration:
FIG. 9 is a block diagram showing a schematic configuration of the image processing apparatus 100a according to the second embodiment. The first aspect of the image processing apparatus 100a in the second embodiment is that the mask selection map 41 is omitted and that the dither mask 43 is provided in place of the first dither mask 42a and the second dither mask 42b. It is different from the image processing device 100 of the embodiment. Since the other configurations of the image processing apparatus 100a of the second embodiment are the same as those of the image processing apparatus 100 of the first embodiment, the same components are designated by the same reference numerals, and detailed description thereof will be omitted. ..

The dot data generation unit 34 of the first embodiment applies different dither masks to the first region Ar1 and the second region Ar2. On the other hand, the dot data generation unit 34 of the second embodiment applies a single dither mask 43 in all the regions of the image region F1 indicated by the image data. Therefore, the image processing apparatus 100a of the second embodiment does not include the mask selection map 41, and some of the processing procedures in the halftone processing of the second embodiment are the processing of the halftone processing in the first embodiment. Different from the procedure.

B2. Dither mask composition:
FIG. 10 is an explanatory diagram schematically showing the configuration of the dither mask 43 in the second embodiment. The dither mask 43 is a dither mask corresponding to the minimum unit region ArMin. As shown in the lower center of FIG. 10, the dither mask 43 includes the first dither mask portions 43a1, 43a2, 43a3 and 43a4, and the second dither mask portion 43b1. In the present embodiment, the first dither mask portions 43a1, 43a2, 43a3 and 43a4 are applied to the first region Ar1 and used. Further, the second dither mask portion 43b1 is applied to the second region Ar2 and used. In other words, the dot data of the first region Ar1 is generated using the threshold values set in the first dither mask portions 43a1 to 43a4 in the dither mask 43, and the dot data of the second region Ar2 is the second dot data in the dither mask 43. It is generated using the threshold value set in the dither mask unit 43b1.

As shown on the upper left side of FIG. 10, each of the first dither mask portions 43a1, 43a2, 43a3 and 43a4 is configured as a part of the first dither mask 43a. As shown on the upper right side of FIG. 10, the second dither mask portion 43b1 is configured as a part of the second dither mask 43b. The first dither mask 43a and the second dither mask 43b are different dither masks.

The first dither mask 43a has the same threshold value as the first dither mask 42a in the first embodiment. That is, when printing is performed based on the dot data generated by using the first dither mask 43a, the change in graininess with respect to the amount of landing deviation shown in FIG. 3 is the same as that of the first dither mask 42a.

The second dither mask 43b has the same threshold value as the second dither mask 42b in the first embodiment. That is, when printing is performed based on the dot data generated by using the second dither mask 43b, the change in graininess with respect to the amount of landing deviation shown in FIG. 3 is the same as that of the second dither mask 42b.

B3. Details of halftone processing:
FIG. 11 is a flowchart showing a detailed procedure of the halftone processing (step S110) in the second embodiment. The halftone process of the second embodiment is different from the halftone process of the first embodiment in that step S215a is executed instead of step S215. Since the other procedures in the halftone processing of the second embodiment are the same as those of the halftone processing of the first embodiment, the same procedures are designated by the same reference numerals, and detailed description thereof will be omitted.

In the halftone processing of the second embodiment, the threshold value is acquired from the dither mask 43. Specifically, as shown in FIG. 11, when the pixel of interest is specified (step S210), the dot data generation unit 34 acquires a threshold value from the dither mask 43 (step S215a). As described above, since the dither mask 43 has a threshold value set for each pixel corresponding to the minimum unit region ArMin, the dot data generation unit 34 does not refer to the mask selection map 41. The threshold value of the pixel of interest is acquired from the dither mask 43. After the execution of step S215a, the above-mentioned steps S220, S225 and S230 are executed. After that, the process returns to step S205, and the above-mentioned processes of step S210, step S215a, and steps S220 to S230 are repeatedly executed until the halftone processing for all the pixels of the image data is completed.

According to the image processing apparatus 100a of the second embodiment described above, the dither mask 43 includes the first dither mask portions 43a1 to 43a4 configured as a part of the first dither mask 43a and the second dither mask. A second dither mask portion 43b1 configured as a part of the 43b is included, and printing is performed by the printing apparatus 200 based on the dot data generated by using the first dither mask 43a and the second dither mask 43b. When the landing deviation amount is zero, the graininess when the first dither mask 43a is used is higher than the granularity when the second dither mask 43b is used, and the landing deviation amount is higher. The graininess when the second dither mask 43b is used is within the range of the assumed landing deviation amount larger than zero and smaller than the maximum deviation amount gMax assumed in the printing apparatus 200, and the first dither mask 43a is used. The dot data of the first region Ar1 is generated by using the threshold values set in the first dither mask portions 43a1 to 43a4, respectively, so that there is a range of landing deviation amount higher than that of the graininess in the case of being present. Then, since the dot data of the second region Ar2 is generated using the threshold value set in the second dither mask unit 43b1, the dot data generated by using the threshold value set only in the first dither mask unit 43a1 to 43a4. Compared with the case of printing based on the above, when the landing position shift occurs so that the landing deviation amount is within the assumed landing deviation amount range, it is possible to suppress the deterioration of the graininess (image quality) of the entire printed surface.

In addition, since a single dither mask 43 including the first dither mask portions 43a1 to 43a4 and the second dither mask portion 43b1 is used, the storage area of the dither mask 43 can be reduced in the image processing apparatus 100a. Further, as compared with the configuration having the first dither mask and the second dither mask as the dither mask, the process of selecting which dither mask to use, the first dither mask or the second dither mask, can be omitted. , The time required for the process of generating dot data can be shortened. In addition, according to the image processing device 100a of the second embodiment, the same effect as that of the image processing device 100 of the first embodiment is obtained.

C. Modification example:
C1. Modification 1:
FIG. 12 schematically shows a change in graininess with respect to the amount of landing deviation when printing is performed based on dot data generated by using the first dither mask and the second dither mask independently in the first modification. It is explanatory drawing which shows. In FIG. 12, similarly to FIG. 3, the vertical axis indicates graininess and the horizontal axis indicates the amount of landing deviation. In addition, the change in graininess with respect to the amount of landing deviation when printing is performed based on the dot data generated using the first dither mask is represented by a solid line, and printing is performed based on the dot data generated using the second dither mask. The change in graininess with respect to the amount of landing deviation when the above is performed is shown by a broken line.

The graininess when printing is performed based on the dot data generated by using the first dither mask in the first modification is substantially the same as that of the first dither mask 42a shown in FIG. Similar to the first dither mask in the first modification, the graininess when printing is performed based on the dot data generated by using the second dither mask in the first modification is the highest when the amount of landing deviation is zero. It becomes a value, and gradually decreases as the amount of landing deviation increases, and becomes the minimum value when the maximum deviation amount is gMax.

Similar to the example shown in FIG. 3, when the amount of landing deviation is zero, the graininess when printing is performed based on the dot data generated by using the first dither mask is the second dither mask. It is higher than the graininess when printing is performed based on the dot data generated by using. Further, when the amount of landing deviation is in the range of g2 to g3 and printing is performed based on the dot data generated by using the second dither mask, the graininess when printing is performed is the dots generated by using the first dither mask. It is higher than the graininess when printing is performed based on the data.

However, unlike the example shown in FIG. 3, the graininess when printing is performed based on the dot data generated by using the first dither mask is such that the curve showing the change in graininess becomes convex downward. It is declining. Further, when printing is performed based on the dot data generated by using the second dither mask, the graininess showing the change in graininess is convex upward when the amount of landing deviation is in the range of g2 to g3. It is decreasing to become.

When the first dither mask and the second dither mask in the first modification are used, the graininess is obtained when the first dither mask is used as compared with the case where the second dither mask is used in the range of the landing deviation amount from zero to g2. Can be raised. When the amount of landing deviation is in the range of g2 to g3, the graininess can be increased when the second dither mask is used as compared with the case where the first dither mask is used. Within the range of the landing deviation amount from g3 to the maximum deviation amount gMax, the graininess can be increased when the first dither mask is used as compared with the case where the second dither mask is used. Therefore, even in such a configuration, when a certain landing deviation range (the landing deviation amount shown in FIG. 12 is within the range of g2 to g3) occurs, only the first dither mask is used. Compared with this, since the graininess can be increased, the same effect as that of the first embodiment is obtained.

Further, the characteristics regarding the graininess of the first dither mask 42a and the second dither mask 42b in the first embodiment are not limited to the characteristics shown in FIGS. 3 and 12. That is, in general, the first dither mask and the second dither mask are the amount of ink landing deviation on the print medium P when printing is performed by the printing apparatus 200 based on the dot data generated by using the respective dither masks. When is zero, the granularity when the first dither mask is used is higher than the granularity when the second dither mask is used, the amount of landing deviation is larger than zero, and it is assumed in the printing apparatus 200. Within the assumed landing deviation amount range smaller than the maximum displacement amount, there is a landing deviation amount range in which the granularity when the second dither mask is used is higher than the granularity when the first dither mask is used. In addition, if the configurations are set respectively, the same effect as that of the first embodiment is obtained.

Similarly, the characteristics related to the graininess of the first dither mask 43a and the second dither mask 43b of the second embodiment are not limited to the characteristics shown in FIGS. 3 and 12. That is, in general, the first dither mask 43a and the second dither mask 43b are printed media P when printing is performed by the printing apparatus 200 based on the dot data generated by using the respective dither masks. When the amount of landing deviation of the ink is zero, the graininess when the first dither mask 43a is used is higher than the graininess when the second dither mask 43b is used, and the amount of landing deviation is zero. The graininess when the second dither mask 43b is used is the same as when the first dither mask 43a is used within the range of the assumed landing deviation amount which is larger and smaller than the maximum deviation amount assumed by the printing apparatus 200. If the configurations are set so that the landing deviation amount range is higher than that of the granularity, the same effect as that of the second embodiment can be obtained.

C2. Modification 2:
FIG. 13 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the first aspect in the modified example 2. In FIG. 13, the image data and the minimum unit area ArMin are not shown. The same applies to the following description. As shown in FIG. 13, each first region Ar1 has a single triangular shape. Each second region Ar2 also has a single triangular shape. The boundary lines L1, L2 and L3 are all straight lines. The boundary line L1 is parallel to the main scanning direction D1. The boundary lines L2 and L3 intersect the main scanning direction D1 and the sub-scanning direction D2, respectively.

FIG. 14 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the second aspect in the modified example 2. The first region Ar1 and the second region Ar2 of the second aspect in the second modification are the first region Ar1 and the second region Ar2 of the second aspect of the second embodiment rotated clockwise by 90 degrees. is there. The boundary line L1 is parallel to the sub-scanning direction D2.

FIG. 15 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the third aspect in the modified example 2. The first region Ar1 and the second region Ar2 of the third aspect in the modified example 2 are embodiments in which the first region Ar1 and the second region Ar2 of the first aspect of the modified example 2 are rotated clockwise by about 25 degrees. Is. Therefore, the boundary lines L1, L2, and L3 intersect the main scanning direction D1 and the sub-scanning direction D2, respectively.

According to the configuration of the first region Ar1 and the second region Ar2 in the second modification described above, the same effects as those of the above-described embodiments can be obtained. In addition, according to the first region Ar1 and the second region Ar2 of the third aspect in the second modification, all of the boundary lines L1 to L3 between the first region Ar1 and the second region Ar2 are in the main scanning direction D1. And because it intersects with the sub-scanning direction D2, the boundary between the first region Ar1 and the second region Ar2 can be made inconspicuous in the printed image.

C3. Modification 3:
FIG. 16 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the first aspect in the modified example 3. As shown in FIG. 16, each first region Ar1 has a single regular hexagonal shape. Each second region Ar2 also has a single regular hexagonal shape. The boundary lines L1 and L2 are not straight lines but have a concavo-convex shape that matches the shapes of the first region Ar1 and the second region Ar2. The boundaries L1 and L2 intersect the main scanning direction D1.

FIG. 17 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the second aspect in the modified example 3. As shown in FIG. 17, each first region Ar1 has a single regular pentagon shape. Each second region Ar2 also has a single regular pentagon shape. The boundary lines L1 and L2 are not straight lines but have a concavo-convex shape that matches the shapes of the first region Ar1 and the second region Ar2. The boundaries L1 and L2 intersect the main scanning direction D1.

FIG. 18 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the third aspect in the modified example 3. The first region Ar1 and the second region Ar2 of the third aspect in the modified example 3 are embodiments in which the first region Ar1 and the second region Ar2 of the first aspect of the modified example 3 are rotated clockwise by about 25 degrees. Is. Therefore, the boundary lines L1 and L2 intersect the main scanning direction D1 and the sub-scanning direction D2, respectively.

According to the configuration of the first region Ar1 and the second region Ar2 in the modification 3 described above, the same effect as that of each of the above-described embodiments can be obtained. In addition, since the boundary line between the first region Ar1 and the second region Ar2 is not a straight line, the boundary between the first region Ar1 and the second region Ar2 can be made inconspicuous in the printed image.

C4. Modification 4:
FIG. 19 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the first aspect in the modified example 4. The first region Ar1 and the second region Ar2 have different shapes from each other. Specifically, each first region Ar1 has a regular hexagonal shape. Each second region Ar2 has a diamond shape. The second region Ar2 is smaller than the first region Ar1. The boundary lines L1 and L2 are not straight lines but have a concavo-convex shape that matches the shapes of the first region Ar1 and the second region Ar2. The boundaries L1 and L2 intersect the main scanning direction D1.

FIG. 20 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the second aspect in the modified example 4. Each first region Ar1 has a regular hexagonal shape. Each second region Ar2 has a polygonal shape. The boundaries L1 and L2 intersect the main scanning direction D1. The boundary line L1 and the boundary line L2 are a parallel portion parallel to the main scanning direction D1 (hereinafter, referred to as a “main scanning direction parallel portion”) and a parallel portion parallel to the sub scanning direction D2 (hereinafter, ““ main scanning direction parallel portion”). It is referred to as a "sub-scanning direction parallel portion"). Specifically, the boundary line L1 has four main scanning direction parallel portions P1, P2, P3 and P4, and two sub scanning direction parallel portions Q1 and Q2. The boundary line L2 has four main scanning direction parallel portions P5, P6, P7 and P8, and two sub scanning direction parallel portions Q3 and Q4. The main scanning direction parallel portions P1 to P8 are not in contact with each other. The sub-scanning direction parallel portions Q1 to Q2 are not in contact with each other.

FIG. 21 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 of the third aspect in the modified example 4. Each first region Ar1 has a regular octagonal shape. Each second region Ar2 has a polygonal shape. The boundaries L1 and L2 intersect the main scanning direction D1. The boundary line L1 has four main scanning direction parallel portions P1, P2, P3 and P4, and five sub scanning direction parallel portions Q1, Q2, Q3, Q4 and Q5. The boundary line L2 has four main scanning direction parallel portions P5, P6, P7 and P8, and five sub scanning direction parallel portions Q6, Q7, Q8, Q9 and Q10. The main scanning direction parallel portions P1 to P8 are not in contact with each other. The sub-scanning direction parallel portions Q1 to Q10 are not in contact with each other.

According to the configuration of the first region Ar1 and the second region Ar2 in the modified example 4 described above, the same effects as those of the above-described embodiments can be obtained. In addition, since the plurality of main scanning direction parallel portions P1 to P8 are not in contact with each other and the plurality of sub scanning direction parallel portions Q1 to Q10 are not in contact with each other, the main scanning direction parallel portion and the sub scanning direction parallel portion are not in contact with each other. The boundary between the first region Ar1 and the second region Ar2 can be made less noticeable in the printed image as compared with the configuration in which the two regions are continuous with each other. In the present modification 4, both the main scanning direction parallel portion and the sub scanning direction parallel portion are provided, but one of the main scanning direction parallel portion and the sub scanning direction parallel portion is used as a parallel portion. Even in a configuration having a plurality of components, the same effect as in the present modification 4 is obtained.

C5. Modification 5:
FIG. 22 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 in the modified example 5. FIG. 22 shows, in order from the left, the configuration of the first region Ar1, the configuration of the second region Ar2, and the configurations of the first region Ar1 and the second region Ar2 applied to the image region F1, respectively. For convenience of explanation, the first region Ar1 in FIG. 22 is provided with hatching different from the examples shown up to FIG. 21.

As shown on the left side of FIG. 22, each first region Ar1 has an octagonal shape. The first regions Ar1 adjacent to each other along the main scanning direction D1 are arranged so as to be in contact with the sides along the sub-scanning directions D2. The first regions Ar1 adjacent to each other along the sub-scanning direction D2 are arranged so as to be in contact with the sides along the main scanning direction D1. As shown in the center of FIG. 22, each second region Ar2 also has an octagonal shape. The second regions Ar2 adjacent to each other along the main scanning direction D1 are arranged so as to be in contact with the sides along the sub-scanning directions D2. The second regions Ar2 adjacent to each other along the sub-scanning direction D2 are arranged so as to be in contact with the sides along the main scanning direction D1. As shown on the right side of FIG. 22, in the image region F1, the first region Ar1 and the second region Ar2 have regions (hereinafter, referred to as “overlapping regions”) Ar1 + Ar2 in which some regions overlap each other. Therefore, even the smallest unit region ArMin composed of four first regions Ar1 and one second region Ar2 also has overlapping regions Ar1 + Ar2.

Also in the present modification 5, the dot data of each of the first region Ar1 and the second region is generated in the same manner as in each of the above-described embodiments. That is, the dot data of the first region Ar1 is generated by using the threshold value set in the first dither mask 42a, and the dot data of the second region Ar2 is generated by using the threshold value set in the second dither mask 42b. To. In the overlapping region Ar1 + Ar2, which of the first dither mask 42a and the second dither mask 42b to use the threshold value set for the dither mask is determined, for example, as follows.

In the region close to the first region Ar1 in the overlapping region Ar1 + Ar2, it is determined that the region using the threshold value set in the first dither mask 42a is larger than the region using the threshold value set in the second dither mask 42b. .. Further, in the region close to the second region Ar2 in the overlapping region Ar1 + Ar2, the region using the threshold value set in the second dither mask 42b is larger than the region using the threshold value set in the first dither mask 42a. decide. That is, in the overlapping region Ar1 + Ar2, the usage rate of the threshold value set in the first dither mask 42a is determined so as to gradually decrease from the region near the first region Ar1 to the region near the second region Ar2, and the second dither The usage rate of the threshold value set in the mask 42b is determined so as to gradually increase from the region near the first region Ar1 to the region near the second region Ar2. By gradually changing the usage ratio of the first dither mask 42a and the second dither mask 42b in the overlapping region Ar1 + Ar2 in this way, the boundary between the first dither mask 42a and the second dither mask Ar2 is further defined in the printed image. It can be made inconspicuous.

In the above-described modification 5, when the dither mask 43 in the second embodiment is used, the ratio of the regions to which the first dither mask 43a and the second dither mask 43b are applied in the overlapping regions Ar1 + Ar2 is stepped. The same effect as that of the above-mentioned modification 5 can be obtained by changing the target.

C6. Modification 6:
FIG. 23 is an explanatory diagram showing the configuration of the first region Ar1 and the second region Ar2 in the modified example 6. Each first region Ar1 has a single quadrangular shape. Each second region Ar2 also has a single quadrangular shape. The boundary line L1 intersects the main scanning direction D1 and the sub-scanning direction D2, respectively. As shown in FIG. 22, when the first region Ar1 and the second region Ar2 are repeatedly applied in the main scanning direction D1 and the sub-scanning direction D2, respectively, they have a checkered pattern shape. Even in such a configuration, the same effect as that of each of the above-described embodiments can be obtained.

C7. Modification 7:
In each of the above embodiments and modifications, the first region Ar1 and the second region Ar2 have a polygonal shape, but the shape is not limited to a polygon, and is surrounded by one continuous line such as a circle. It may have any shape of. It may be a shape showing a circle arranged in the center in the minimum unit area ArMin of a square shape and other areas excluding the circle in the minimum unit area ArMin. Moreover, the polygon is not limited to the regular polygon. Even in such a configuration, the same effect as that of each of the above-described embodiments can be obtained.

C8. Modification 8:
In each of the above embodiments and modifications, the main scanning direction D1 corresponds to the first direction in the means for solving the problem, and the sub-scanning direction D2 corresponds to the second direction in the means for solving the problem. The first direction is not limited to the main scanning direction D1, and the second direction is not limited to the sub-scanning direction D2, and may be any other direction. Further, the second direction (sub-scanning direction D2) is a direction orthogonal to the first direction (main scanning direction D1), but it is not limited to being orthogonal and may intersect. Even in such a configuration, the same effects as those of the above-described embodiments and modifications can be obtained.

C9. Modification 9:
In each of the above embodiments, the minimum unit region ArMin is not limited to the example shown in FIG. For example, as shown in FIG. 6, a region in which three minimum unit regions ArMin are continuously applied along the main scanning direction D1 and a sub-scanning direction D2, that is, a region in which a total of nine minimum unit regions ArMin are gathered. May be the minimum unit region ArMin. In this case, even in the mask selection map 41, the same effect as that of the first embodiment is obtained by storing the set values in advance in the pixels corresponding to the area where a total of nine minimum unit areas ArMin are gathered. ..

C10. Modification 10:
In each of the above embodiments, the halftone process (step S105) can be performed independently for each color component of each ink color C, M, Y, and K, but the present invention is not limited thereto. For example, halftone processing units 33 may be prepared for the number of ink colors and executed in parallel for four colors at the same time. It may be executed in order for each color in units of one line or one screen.

C11. Modification 11:
In each of the above embodiments, the printing apparatus 200 is an inkjet printer that prints with four colors of ink (cyan, magenta, yellow, and black), but the present invention is not limited thereto. For example, the number of inks used may differ from the above. Specifically, in addition to the above-mentioned four-color ink, seven colors including three-color inks of light gray, light cyan, and light magenta may be used. Even in these configurations, the same effects as those of the above-described embodiments are obtained.

C12. Modification 12:
In each of the above embodiments, another device may have at least a part of the functions of the image processing device 100. For example, the printing device 200 may have a halftone processing unit 33. Further, the printing device 200 may have all the functions of the image processing device 100. Even in these configurations, the same effect as that of the embodiment can be obtained.

C13. Modification 13:
In the embodiments and modifications, a part of the configuration realized by the hardware may be replaced with software, and conversely, a part of the configuration realized by the software may be replaced with hardware. Good. Further, when a part or all of the functions of the present invention are realized by software, the software (computer program) can be provided in a form stored in a computer-readable recording medium. In the present invention, the "computer-readable recording medium" is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but is an internal storage device in a computer such as various RAMs or ROMs, a hard disk, or the like. It also includes an external storage device that is fixed to your computer. That is, the term "computer-readable recording medium" has a broad meaning including any recording medium on which data can be fixed rather than temporarily.

The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit of the present invention. For example, the embodiments corresponding to the technical features in each of the embodiments described in the column of the outline of the invention, the technical features in the modified examples are used to solve some or all of the above-mentioned problems, or the above-mentioned above. It is possible to replace or combine them as appropriate to achieve some or all of the effects. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

20 ... application, 30 ... printer driver, 31 ... resolution conversion unit, 32 ... color conversion unit, 33 ... halftone processing unit, 34 ... dot data generation unit, 35 ... print data output unit, 40 ... color conversion table, 41 ... Map for mask selection, 42a ... 1st data mask, 42b ... 2nd data mask, 43 ... data mask, 43a ... 1st original data mask, 43a1 ... 1st data mask part, 43a2 ... 1st data mask part, 43a3 ... 1st data mask unit, 43a4 ... 1st data mask unit, 43b ... 2nd original data mask unit, 43b1 ... 2nd data mask unit, 50 ... memory, 100 ... image processing device, 100a ... image processing device, 200 ... printing device , 220 ... Control unit, 230 ... Head unit, 231 ... Carriage, 232 ... Ink cartridge, 233 ... Print head, 240 ... Carriage motor, 250 ... Conveyor motor, 261 ... Drive belt, 262 ... Flexible cable, 263 ... Platen, Ar1 ... 1st area, Ar2 ... 2nd area, Ar1 + Ar2 ... Overlapping area, ArMin ... Minimum unit area, CMYK ... Ink color, D1 ... Main scanning direction, D2 ... Sub-scanning direction, F1 ... Image area, L1 ... Borderline, L2 ... Boundary line, L3 ... Boundary line, L4 ... Boundary line, P ... Print medium, P1 ... Main scanning direction parallel part, P2 ... Main scanning direction parallel part, P3 ... Main scanning direction parallel part, P4 ... Main scanning direction parallel part , P5 ... Main scanning direction parallel part, P6 ... Main scanning direction parallel part, P7 ... Main scanning direction parallel part, P8 ... Main scanning direction parallel part, Q1 ... Sub-scanning direction parallel part, Q2 ... Sub-scanning direction parallel part, Q3 ... Sub-scanning direction parallel part, Q4 ... Sub-scanning direction parallel part, Q5 ... Sub-scanning direction parallel part, Q6 ... Sub-scanning direction parallel part, Q7 ... Sub-scanning direction parallel part, Q8 ... Sub-scanning direction parallel part, Q9 ... Sub Scanning direction parallel part, Q10 ... Sub-scanning direction parallel part, g1 ... Landing deviation amount, g2 ... Landing deviation amount, g3 ... Landing deviation amount, gMax ... Maximum deviation amount

Claims (13)

An image processing device including a dot data generation unit that generates dot data indicating the presence or absence of ink dots on a medium in a printing device using image data expressed by gradation values and a threshold set in a dither mask. There,
As the dither mask, a first dither mask and a second dither mask different from the first dither mask
Has a dither mask
When the first dither mask and the second dither mask are printed by the printing apparatus based on the dot data generated by using the respective dither masks,
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second dither mask is used is the same as that of the first dither mask. Each is set so that there is a higher landing deviation amount range than the graininess when used.
The dot data generation unit
In the image region indicated by the image data, in the first region having a plurality of pixels in each of the first direction and the second direction orthogonal to the first direction, the threshold value set in the first dither mask is set. To generate the dot data in the first region using
The second dither mask is set in a second region of the image region, which is different from the first region and has a plurality of pixels in each of the first direction and the second direction. The dot data of the second region is generated by using the threshold value.
The first region and the second region have a boundary line that intersects both the first direction and the second direction.
Image processing device. An image processing device including a dot data generation unit that generates dot data indicating the presence or absence of ink dots on a medium in a printing device using image data expressed by gradation values and a threshold set in a dither mask. There,
The dither mask includes a first dither mask portion and a second dither mask portion.
The first dither mask portion is applied to and used in the first region having a plurality of pixels in the first direction and the second direction orthogonal to the first direction in the image region indicated by the image data. Be,
The second dither mask portion is applied to a second region of the image region, which is different from the first region and has a plurality of pixels in each of the first direction and the second direction. Used as
The first region and the second region have a boundary line that intersects both the first direction and the second direction.
The first dither mask portion is configured as a part of the first dither mask.
The second dither mask portion is configured as a part of a second dither mask different from the first dither mask.
The first dither mask and the second dither mask are used when printing is performed by the printing apparatus based on dot data generated by using the respective dither masks.
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second element dither mask is used is the first element dither. Each is set so that there is a higher landing deviation amount range than the graininess when using a mask.
Image processing device. An image processing device including a dot data generation unit that generates dot data indicating the presence or absence of ink dots on a medium in a printing device using image data expressed by gradation values and a threshold set in a dither mask. There,
As the dither mask, a first dither mask and a second dither mask different from the first dither mask
Has a dither mask
When the first dither mask and the second dither mask are printed by the printing apparatus based on the dot data generated by using the respective dither masks,
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second dither mask is used is the same as that of the first dither mask. Each is set so that there is a higher landing deviation amount range than the graininess when used.
The dot data generation unit
In the image region indicated by the image data, in the first region having a plurality of pixels in each of the first direction and the second direction intersecting with the first direction, the threshold value set in the first dither mask is set. To generate the dot data in the first region using
The second dither mask is set in a second region of the image region, which is different from the first region and has a plurality of pixels in each of the first direction and the second direction. The dot data of the second region is generated by using the threshold value.
In a unit area in the image area, which is composed of a plurality of the first area and a plurality of the second areas, a part of the first area and the second area overlap each other. ing,
Image processing device. An image processing device including a dot data generation unit that generates dot data indicating the presence or absence of ink dots on a medium in a printing device using image data expressed by gradation values and a threshold set in a dither mask. There,
The dither mask includes a first dither mask portion and a second dither mask portion.
The first dither mask portion is applied to and used in the first region having a plurality of pixels in the first direction and the second direction intersecting the first direction in the image region indicated by the image data. Be,
The second dither mask portion is applied to a second region of the image region, which is different from the first region and has a plurality of pixels in each of the first direction and the second direction. Used as
In a unit area in the image area, which is composed of a plurality of the first area and a plurality of the second areas, a part of the first area and the second area overlap each other. And
The first dither mask portion is configured as a part of the first dither mask.
The second dither mask portion is configured as a part of a second dither mask different from the first dither mask.
The first dither mask and the second dither mask are used when printing is performed by the printing apparatus based on dot data generated by using the respective dither masks.
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second element dither mask is used is the first element dither. Each is set so that there is a higher landing deviation amount range than the graininess when using a mask.
Image processing device. In the image processing apparatus according to any one of claims 1 to 4.
In a unit region in the image region, which is a unit region including a plurality of the first region and a plurality of the second regions.
The first region has a single polygonal shape and has a single polygonal shape.
The second region has a single polygonal shape.
Image processing device. In the image processing apparatus according to any one of claims 1 to 5.
The first region and the second region have different shapes from each other.
Image processing device. In the image processing apparatus according to any one of claims 1 to 6.
The boundary line between the first region and the second region is a plurality of parallel portions parallel to one of the first direction and the second direction, and a plurality of parallel portions not in contact with each other. Have,
Image processing device. In the image processing apparatus according to any one of claims 1 to 7.
In a unit region in the image region, which is a unit region including a plurality of the first region and a plurality of the second regions.
A part of the first region and the second region overlap each other.
Image processing device. The image processing apparatus according to any one of claims 1 to 8 is provided.
Printing device. A computer program for generating dot data indicating the presence or absence of ink dots on a medium in a printing apparatus by using image data expressed by gradation values and a threshold set in a dither mask.
As the dither mask, a first dither mask and a second dither mask different from the first dither mask
A function to read the threshold value from the dither mask,
In the image region indicated by the image data, the threshold value read from the first dither mask is set in the first region having a plurality of pixels in each of the first direction and the second direction orthogonal to the first direction. With the function of generating the dot data of the first region by using
The image region is a region different from the first region, and has a plurality of pixels in each of the first direction and the second direction, and both of the first direction and the second direction. A function of generating the dot data of the second region using the threshold value read from the second dither mask in the second region having an intersecting boundary line between the first region and the first region.
To the computer,
When the first dither mask and the second dither mask are printed by the printing apparatus based on the dot data generated by using the respective dither masks,
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second dither mask is used is the same as that of the first dither mask. Each is set so that there is a higher landing deviation amount range than the graininess when used.
Computer program. A computer program for generating dot data indicating the presence or absence of ink dots on a medium in a printing apparatus by using image data expressed by gradation values and a threshold set in a dither mask.
A function of reading a threshold value from the dither mask including the first dither mask portion and the second dither mask portion, and
A function to generate the dot data using the threshold value read from the dither mask, and
To the computer,
The first dither mask portion is applied to and used in the first region having a plurality of pixels in the first direction and the second direction orthogonal to the first direction in the image region indicated by the image data. Be,
The second dither mask portion is a region of the image region that is different from the first region, and has a plurality of pixels in the first direction and the second direction, respectively, in the first direction. It is used by applying it to a second region having a boundary line intersecting with both the first region and the first region.
The first dither mask portion is configured as a part of the first dither mask.
The second dither mask portion is configured as a part of a second dither mask different from the first dither mask.
The first dither mask and the second dither mask are used when printing is performed by the printing apparatus based on dot data generated by using the respective dither masks.
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second element dither mask is used is the first element dither. Each is set so that there is a higher landing deviation amount range than the graininess when using a mask.
Computer program. A computer program for generating dot data indicating the presence or absence of ink dots on a medium in a printing apparatus by using image data expressed by gradation values and a threshold set in a dither mask.
As the dither mask, a first dither mask and a second dither mask different from the first dither mask
A function to read the threshold value from the dither mask,
In the image region indicated by the image data, the threshold value read from the first dither mask is set in the first region having a plurality of pixels in each of the first direction and the second direction intersecting the first direction. With the function of generating the dot data of the first region by using
In the second region of the image region, which is different from the first region and has a plurality of pixels in the first direction and the second direction, the data is read from the second dither mask. A function to generate the dot data in the second region using the threshold value, and
To the computer,
In a unit area in the image area, which is composed of a plurality of the first area and a plurality of the second areas, a part of the first area and the second area overlap each other. And
When the first dither mask and the second dither mask are printed by the printing apparatus based on the dot data generated by using the respective dither masks,
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second dither mask is used is the same as that of the first dither mask. Each is set so that there is a higher landing deviation amount range than the graininess when used.
Computer program. A computer program for generating dot data indicating the presence or absence of ink dots on a medium in a printing apparatus by using image data expressed by gradation values and a threshold set in a dither mask.
A function of reading a threshold value from the dither mask including the first dither mask portion and the second dither mask portion, and
A function to generate the dot data using the threshold value read from the dither mask, and
To the computer,
The first dither mask portion is applied to and used in the first region having a plurality of pixels in the first direction and the second direction intersecting the first direction in the image region indicated by the image data. Be,
The second dither mask portion is applied to a second region of the image region, which is different from the first region and has a plurality of pixels in each of the first direction and the second direction. Used as
In a unit area in the image area, which is composed of a plurality of the first area and a plurality of the second areas, a part of the first area and the second area overlap each other. And
The first dither mask portion is configured as a part of the first dither mask.
The second dither mask portion is configured as a part of a second dither mask different from the first dither mask.
The first dither mask and the second dither mask are used when printing is performed by the printing apparatus based on dot data generated by using the respective dither masks.
When the amount of landing deviation of the ink in the medium is zero, the graininess when the first dither mask is used is higher than the graininess when the second dither mask is used.
Within the range of the assumed landing deviation amount in which the landing deviation amount is larger than zero and smaller than the maximum deviation amount assumed in the printing apparatus, the graininess when the second element dither mask is used is the first element dither. Each is set so that there is a higher landing deviation amount range than the graininess when using a mask.
Computer program.

Images