Printing device, control method thereof, and program

Abstract

To provide a printing device, a control method thereof, and a program for improving color proofing of an image.SOLUTION: A printing device 10 includes a head that prints an image having a plurality of pixels on a print medium on the basis of image data, and an input device 14 capable of specifying pixels of the image, and a control device 50, and the control device executes a printing operation of printing, on the same print medium, a first patch group including a plurality of patches, and a second patch group having a pair of patches with a smaller color difference than a pair of patches with the smallest color difference in the first patch group including patches corresponding to designated pixels designated by the input device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus, a control method thereof, and a program. [Background technology]

[0002] An example of a conventional printing device is the image processing device described in Patent Document 1. This image processing device prints a plurality of predetermined color patches on a printing medium, measures the printed color patches, and obtains a plurality of colorimetric values. The image processing device then extracts a color patch from the plurality of colorimetric values ​​that has a colorimetric value close to the color of a pixel in the image data to be printed, and converts the color of the image data to be printed based on the colorimetric value of the extracted color patch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-198079 Summary of the Invention [Problem to be solved by the invention]

[0004] In the image processing device, the colors of the image data to be printed are calibrated based on the colorimetric values ​​of predetermined color patches. However, for images with small color differences between pixels, such as images with gradations, the colors of the image may not be properly calibrated using the predetermined color patches.

[0005] In view of the above, an object of the present invention is to provide a printing apparatus that can improve color proofing of an image, a control method thereof, and a program. [Means for solving the problem]

[0006] A printing device according to one aspect of the present invention comprises a head that prints an image having multiple pixels on a printing medium based on image data, an input device that can specify pixels of the image, and a control device, wherein the control device performs a printing operation to print on the same printing medium a first patch group that includes multiple patches and a second patch group that includes patches corresponding to specified pixels specified by the input device and has a pair of patches that has a smaller color difference than the pair of patches in the first patch group that has the smallest color difference.

[0007] A control method for a printing device according to one aspect of the present invention is a control method for a printing device that has a head that prints an image having multiple pixels on a printing medium based on image data, and an input device that can specify pixels of the image, and performs a printing operation that prints on the same printing medium a first patch group that includes multiple patches, and a second patch group that includes patches corresponding to specified pixels specified by the input device, and has a pair of patches that has a smaller color difference than the pair of patches in the first patch group that has the smallest color difference.

[0008] A program according to one aspect of the present invention causes a computer having a head that prints an image having multiple pixels on a printing medium based on image data and an input device that can specify pixels of the image to perform a printing operation that prints on the same printing medium a first patch group that includes multiple patches and a second patch group that includes patches corresponding to specified pixels specified by the input device, the second patch group having a pair of patches that has a smaller color difference than the pair of patches in the first patch group that has the smallest color difference. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a printing device that can improve color proofing of an image, a control method thereof, and a program.

[0010] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a printing device according to an embodiment and a modification of the present invention, as viewed from above. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the printing device. [Figure 3] FIG. 3 is a flowchart showing an example of a control method for a printing device. [Figure 4] FIG. 4 is a flowchart showing an example of the adding operation. [Figure 5] FIG. 5 is a top view of a print medium on which a patch chart is printed. [Figure 6] FIG. 6 is a diagram showing a display device on which an image is displayed. [Figure 7] FIG. 7 is a diagram showing a display device on which an image is displayed. [Figure 8] FIG. 8 is a table showing pixel color values, inter-position distances, and priorities. [Figure 9] 9(a) to 9(c) are diagrams showing pixels in an image to explain the search operation. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

[0013] <Printing device configuration> 1 and 2, a printing device 10 according to an embodiment of the present invention is a device that ejects ink from nozzles 21 of a head 20 onto a printing medium A and prints an image E on the printing medium A using the ink. Below, an example in which the printing device 10 is applied to an inkjet printer will be described, but the printing device 10 is not limited to this. The printing medium A is a sheet of paper, cloth, or the like.

[0014] The printing device 10 is a serial head type and includes a head 20, a platen 11, a tank 12, a display device 13, an input device 14, a colorimeter 15, a conveying device 30, a scanning device 40, and a control device 50. The direction in which the printing medium A is conveyed by the conveying device 30 is referred to as the front-rear direction. Directions that intersect (e.g., perpendicular to) the front-rear direction and intersect (e.g., perpendicular to) each other are referred to as the left-right direction and the up-down direction. However, the arrangement of the printing device 10 is not limited to this. The printing device 10 may also be a line head type. In this case, the printing device 10 does not include a scanning device 40, and the length of the head 20 is longer than the length of the printing medium A in the left-right direction.

[0015] The head 20 has multiple nozzles 21 and multiple drive elements 24, and the nozzles 21 open to the bottom surface of the head 20. The drive elements 24 are piezoelectric elements, heating elements, electrostatic actuators, etc., and are provided for each nozzle 21. They apply pressure to the ink to eject it from the nozzle 21. The platen 11 has a flat upper surface and defines the distance between the print medium A placed on that upper surface and the bottom surface of the head 20 provided opposite it. The number of tanks 12 is equal to the number of ink types, for example, four. The four tanks 12 store cyan ink, yellow ink, magenta ink, and black ink, respectively. Each tank 12 is connected to the head 20 by a tube 12a and supplies ink to the nozzles 21 of the head 20 via the tube 12a.

[0016] The transport device 30 has, for example, two transport rollers 31 and a transport motor 32. The two transport rollers 31 are arranged in the front-to-rear direction with the platen 11 sandwiched between them. The transport roller 31 has a shaft extending in the left-to-right direction and is connected to the transport motor 32. The transport roller 31 rotates about the shaft when driven by the transport motor 32, transporting the printing medium A in the front-to-rear direction on the platen 11.

[0017] The scanning device 40 has a carriage 41, two guide rails 42, a scanning motor 43, and an endless belt 44. The carriage 41 carries the head 20 and is supported by the two guide rails 42 so as to be movable in the left-right direction. The two guide rails 42 extend in the left-right direction above the platen 11 so as to sandwich the head 20 between them in the front-to-rear direction. The endless belt 44 extends in the left-right direction and is attached to the carriage 41, and is attached to the scanning motor 43 via a pulley 45. When the scanning motor 43 is driven, the endless belt 44 runs, and the carriage 41 moves back and forth in the left-right direction along the guide rails 42. As a result, the carriage 41 moves the head 20 in the left-right direction.

[0018] <Control devices, display devices, input devices, colorimeters> As shown in Fig. 2, the control device 50 is, for example, a computer and includes an interface 51, a calculation unit 52, and a storage unit 53. The interface 51 receives various data, such as image data and target color data, from external devices such as a computer, a camera, a communication network, a recording medium, a display, and a printer. The image data is, for example, raster data representing an image E to be printed on a print medium A. The control device 50 may be configured as a single device, or may be configured as multiple devices distributed in a distributed arrangement that work together to perform the operations of the printing device 10.

[0019] The storage unit 53 is a memory accessible from the calculation unit 52 and includes a RAM and a ROM. The RAM temporarily stores various data such as image data and data converted by the calculation unit 52. The ROM stores programs and tables for performing various data processing. The programs may be stored in an external storage medium different from the storage unit 53 and accessible from the calculation unit 52, such as a CD-ROM.

[0020] The calculation unit 52 includes, for example, a processor such as a CPU or a circuit such as an integrated circuit such as an ASIC. The calculation unit 52 controls each unit by executing a program and performs various operations such as printing. Details of the various operations will be described later.

[0021] The control device 50 is electrically connected to the display device 13, the input device 14, and the colorimeter 15. The display device 13 is, for example, a display, and displays the image E to be printed by the printing operation. The input device 14 is, for example, a mouse, a touch panel, or the like, and is operated by a user to input data to the control device 50. The colorimeter 15 is, for example, a spectrophotometer, or the like, and measures the color of the image E on the printing medium A and inputs the measured color to the control device 50.

[0022] The control device 50 is also electrically connected to the transport motor 32 of the transport device 30 via the transport drive circuit 33, and controls the driving of the transport motor 32. This controls the transport of the print medium A by the transport device 30. The control device 50 is also electrically connected to the scan motor 43 of the scanning device 40 via the scan drive circuit 46, and controls the driving of the scan motor 43. This controls the movement of the head 20 by the scanning device 40.

[0023] The control device 50 is also electrically connected to the drive elements 24 via the head drive circuit 25. The control device 50 outputs a control signal for the drive elements 24 to the head drive circuit 25, and the head drive circuit 25 generates a drive signal based on the control signal and outputs it to the drive elements 24. The drive elements 24 are driven in response to the drive signal, causing ink to be ejected from the nozzles 21.

[0024] <Printing operation> In this printing device 10, the control device 50 acquires image data and executes a printing operation based on the image data. For example, the control device 50 ejects ink from the head 20 onto the printing medium A while moving the head 20 to the right or left. The control device 50 then transports the printing medium A forward. In this way, the printing device 10 alternately repeats the movement of the head 20, the ejection of ink, and the transportation of the printing medium A, to proceed with the printing operation of printing an image E on the printing medium A with ink.

[0025] <Printing device control method> The control method for the printing device 10 is executed by the control device 50, for example, in accordance with the flowchart showing an example of the control method in Fig. 3. Here, the control device 50 acquires conditions for color calibration (step S1). The conditions include, for example, the size or type of printing medium A for printing patches, and the size of the patches to be printed.

[0026] Examples of sizes of the printing medium A include paper sizes such as A4 and B5. Examples of types of the printing medium A include T-shirts and towels. The size or type of the printing medium A and the size of the printing area A1 on the printing medium A are associated in advance and stored in the storage unit 53. Based on this relationship, the control device 50 obtains the size of the printing area A1 from the size or type of the printing medium A. Furthermore, the patch has a predetermined shape, such as a rectangular shape, and a predetermined size. The patch size is a size that allows color measurement by the colorimeter 15. This size may be input to the control device 50 via the input device 14 or the like. Alternatively, this size may be predetermined according to the resolution of the colorimeter 15.

[0027] The control device 50 acquires the first color, which is the color of the first patch group B (step S2). The first patch group B includes a plurality of first patches bn of first colors, each having a color difference equal to or greater than a predetermined threshold. The first colors are predetermined in a color list, and the color list is stored in the storage unit 53. The first colors are colors that represent the color gamut, which is the range of colors that can be reproduced by the printing device 10, in stages, and have device-dependent color coordinates, for example, color values ​​such as RGB values ​​in an RGB color space. For example, the first colors are colors that represent the color gamut of the printing device 10 in predetermined increments, for example, 32 increments, such as RGB values ​​(0, 0, 0) to RGB values ​​(255, 255, 255), and are expressed as (256 / 32+1). 3 In this case, n is a natural number from 1 to 729 in the first patch bn, and the first patch group B has 729 types of first patches bn, that is, first patches b1 to b729.

[0028] The 729 first colors are provided for each color difference of a predetermined threshold. The smallest color difference between two first colors is the predetermined threshold. The predetermined threshold is a value greater than 0, and the 729 first colors are different from each other. The color difference is the difference between one color value and another color value. For example, when RGB values ​​are expressed as color coordinates in an RGB color space formed by a linear three-dimensional space of R, G, and B axes, the color difference is expressed as the inter-color distance, which is the distance between two color coordinates. The greater the color difference between two colors, the greater the inter-color distance between the two RGB values, making it easier to distinguish between the two colors.

[0029] The control device 50 executes an addition operation to add a second color, which is the color of the second patch group C, to the color list (step S3). The second patch group C is a patch group including a patch corresponding to the designated pixel e1 described below, and includes a pair of second patches cm whose color difference is smaller than the pair of first patches bn, which has the smallest color difference among the first patch group B. The m in the second patch cm is a natural number ranging from 1 to the number of colors added by the addition operation. The second color is a color that represents the color gamut of the printing device 10 in stages and has color values ​​such as RGB values. The smallest color difference between the two second colors is greater than 0 and less than a predetermined threshold, e.g., half the threshold. The multiple second colors are different from each other. In other words, the second patch group C includes a patch corresponding to the designated color, which is the color of the designated pixel e1, and a patch whose color difference from the designated color of the designated pixel e1 is greater than 0 and less than a predetermined threshold.

[0030] The adding operation is performed according to the flowchart showing an example of the adding operation in FIG. 4. Here, the control device 50 acquires a designated pixel e1 designated by the input device 14 (step S10). For example, as shown in FIG. 6, the control device 50 acquires image data to be printed and displays an image E on the display device 13. The image E has a plurality of pixels e divided per unit area. The plurality of pixels e are aligned in an x ​​direction and a y direction intersecting (for example, perpendicular to) the x direction on the display device 13 to form the image E. The position of the pixel e may be represented by the x position of the pixel e aligned in the x direction and the x position of the pixel e aligned in the y direction on the image E, or by x coordinates and y coordinates based on a predetermined position on the display device 13.

[0031] The user specifies one or more pixels e to be used for color proofing in the image E displayed on the display device 13 using the input device 14. The control device 50 acquires the position on the display device 13 specified by the input device 14. The control device 50 designates the pixel e corresponding to this specified position as a designated pixel e1, adds its position in the x and y directions, and the color of the designated pixel e1 as a designated color, its color values ​​such as RGB values, to the column No. 0 of the candidate list in FIG. 8, and stores the candidate list in the storage unit 53. If multiple designated pixels e1 are specified, a candidate list is created for each designated pixel e1 and stored in the storage unit 53.

[0032] The control device 50 executes a first setting operation (step S11). In the first setting operation, the control device 50 sets the upper limit number of designated colors and similar colors to the designated color to be added to the color list by the adding operation, depending on the number of first colors included in the first patch group B, the patch size, and the size of the printing area A1 of the printing medium A. In other words, the control device 50 stores the upper limit number, which depends on the number of first colors included in the first patch group B, the patch size, and the size of the printing area A1 of the printing medium A, in a predetermined storage area of ​​the storage unit 53. The patches include a first patch bn of the first patch group B and a second patch cm of the second patch group C.

[0033] In other words, the more patches there are, the more accurate the color calibration, but the more time and effort required for color calibration. Therefore, taking these factors into consideration, the number of colors added to the color list, which is a list of patch colors, is limited. Here, the number of first colors in the first patch group B is predetermined, e.g., 729, which is equal to the number of first patches bn. The control device 50 acquires the size of the patches and the size of the printing area A1 based on the conditions of step S1. The control device 50 calculates the quotient obtained by dividing the size of the printing area A1 by the size of the patches as the total number of patches. The control device 50 calculates the difference obtained by subtracting the number of first patches bn from the total number of patches as the number of second patches cm. The control device 50 calculates the quotient obtained by dividing the number of second patches cm by the number of designated pixels e1 as the upper limit number of designated colors and approximate colors for each designated pixel e1.

[0034] The control device 50 executes a search operation (step S12). The search operation is included in the add operation. In the search operation, the control device 50 searches for a color of a pixel e located around the designated pixel e1 on the image E, the color of which has a color difference from the designated color less than a threshold. The pixels e located around the designated pixel e1 include a pixel e adjacent to the designated pixel e1 in the image E and a pixel e contiguous to the designated pixel e1 via a pixel e in the image E of a color whose color difference from the designated color is less than the threshold. In other words, there is no other pixel e between the designated pixel e1 and the pixel e adjacent to the designated pixel e1. Furthermore, there is no pixel e of a color whose color difference from the designated color is greater than or equal to the threshold between the designated pixel e1 and a pixel e contiguous to the designated pixel e1 via a pixel e in the image E of a color whose color difference from the designated color is less than the threshold. There is at least one pixel e of a color whose color difference from the designated color is less than the threshold between the designated pixel e1 and a pixel e in the image E of a color whose color difference from the designated color is less than the threshold.

[0035] Specifically, as shown in the example of FIG. 7, the control device 50 obtains the color value and position of pixel e in image E from the image data in association with each other. The control device 50 obtains the color difference between the color value of pixel e and the designated color of the designated pixel e1 obtained in step S10. The control device 50 searches for the color of pixel e whose color difference from the designated color is less than a threshold, and extracts regions of pixel e of that color, for example, four regions F1, F2, F3, and F4. Each region is a closed space containing one or more pixels e, and the color difference between the color of the pixel e and the designated color is less than a threshold and is close to the designated color. In a region containing multiple pixels e, two pixels e are adjacent to each other in the x or y direction. The control device 50 obtains region F3 containing the designated pixel e1 from the four regions F1, F2, F3, and F4.

[0036] The region F3 has a first surrounding pixel e2 and a second surrounding pixel e3, which are pixels e located around the designated pixel e1 and whose color difference from the designated color is less than a threshold. The first surrounding pixel e2 is a pixel e adjacent to the designated pixel e1, with no other pixels e between it and the designated pixel e1 in the x or y direction. The second surrounding pixel e3 is located farther from the designated pixel e1 than the first surrounding pixel e2. The first surrounding pixel e2 is located between the designated pixel e1 and the second surrounding pixel e3 in the x or y direction. Alternatively, the first surrounding pixel e2 and one or more second surrounding pixels e3 are located between the designated pixel e1 and the second surrounding pixel e3.

[0037] The control device 50 executes an acquisition operation (step S13). In the acquisition operation, the control device 50 acquires, as an approximate color, the color of a pixel e located around the designated pixel e1 in the image E, the color of which has a color difference from the designated color less than a threshold value. In the example of Fig. 7, the control device 50 acquires the positions of the first surrounding pixel e2 and the second surrounding pixel e3 in the area F3, and approximate colors such as RGB values, from the image data, and adds them to the candidate list in Fig. 8 in the columns No. 1 and onward.

[0038] The control device 50 executes a first determination operation (step S14). In the first determination operation, the control device 50 determines whether the designated color and the approximate color are different from the first color of the first patch group B. For example, if the RGB values ​​of the designated color acquired in step S10 match the RGB values ​​of the predetermined first color, the control device 50 determines that the designated color and the first color are the same (step S14: NO). Also, if the RGB values ​​of the approximate color acquired in step S13 match the RGB values ​​of the predetermined first color, the control device 50 determines that the approximate color and the first color are the same (step S14: NO). On the other hand, if the designated color does not match the first color, the control device 50 determines that the designated color and the first color are different (step S14: YES). If the approximate color does not match the first color, the control device 50 determines that the approximate color and the first color are different (step S14: YES).

[0039] If the designated color and the approximate color are different from the first color (step S14: YES), the control device 50 executes a second determination operation (step S15). That is, for example, if multiple designated pixels e1 are designated, the designated color of the designated pixel e1 and the approximate colors of the surrounding pixels e2 and e3 of the designated pixel e1 are added to the color list for each designated pixel e1. Therefore, when adding the designated color of a designated pixel e1 among the multiple designated pixels e1 to the color list, at least one of the designated colors and approximate colors of other designated pixels e1 may already be added to the color list. To prevent the same color from being added to the color list multiple times, in the second determination operation, the control device 50 determines whether the designated color and approximate colors are different from the colors already added to the color list in the addition operation.

[0040] Specifically, in the second determination operation, for example, if the RGB values ​​of the specified color match the RGB values ​​of the second color of the second patch group C added to the color list, the control device 50 determines that the specified color and the second color in the color list are the same (step S15: NO). If the approximate color matches the second color, the control device 50 determines that the approximate color and the second color are the same (step S15: NO). On the other hand, if the specified color does not match the second color in the color list, the control device 50 determines that the specified color and the second color are different (step S15: YES). If the approximate color does not match the second color in the color list, the control device 50 determines that the approximate color and the second color are different (step S15: YES).

[0041] In this way, the control device 50 performs the first determination operation in step S14 and the second determination operation in step S15 for each of the designated color and the approximate colors acquired in step S13. Here, if the designated color or the approximate color is the same as the first color or the second color (step S14: NO, S15: NO), the control device 50 adds "-" to the priority of pixel e of that color in the candidate list of FIG. 8 and deletes this pixel e from the additional candidate list. Then, the control device 50 determines whether the determination of the designated color and its approximate colors is complete (step S18). If the determination of the designated color and its approximate colors is not complete (step S18: NO), the control device 50 returns to the process of step S14 and executes the subsequent processes.

[0042] If the specified color and the approximate color are different from the second color in the color list (step S15: YES), the control device 50 acquires the inter-position distance, which is the distance between the position of the specified pixel e1 of the specified color and the positions of the surrounding pixels e2 and e3 of the approximate colors of the specified color, as shown in the example of FIG. 8 (step S16). Then, the control device 50 acquires the specified color and the approximate color as additional candidates and adds them to the candidate list (step S17). Then, the control device 50 repeats the processes of steps S14-S17 until the determination of the specified color and its approximate colors is completed.

[0043] Once the determination of the specified color and its approximate colors is complete (step S18: YES), the control device 50 adds up to the upper limit of colors among the candidate colors for addition to the color list in order of priority (step S19). Here, the control device 50 adds the specified color to the color list before approximate colors, and prioritizes adding the specified color over approximate colors. Furthermore, if the control device 50 acquires multiple approximate colors through the acquisition operation, in the addition operation, the control device 50 prioritizes adding approximate colors of the surrounding pixels e2 and e3 that are closer to the specified pixel e1 among the multiple approximate colors to the color list. In other words, the control device 50 increases the priority of adding a pixel e located closer to the specified pixel e1 in image E, and moves it to the front of the addition order. Therefore, colors that exceed the upper limit of the candidate colors for addition are not added to the color list. In other words, the control device 50 decreases the priority of adding a pixel e located farther from the specified pixel e1 in image E. Therefore, a pixel e in image E that is far from the position of the designated pixel e1 is not added to the color list if the number of colors to be added exceeds the upper limit.

[0044] In the candidate list of FIG. 8, pixel e No. 0 is the designated pixel e1, and its distance from the designated pixel e1 is 0. The priority of this designated pixel e1 is 1. Pixel e No. 1 is the first surrounding pixel e2 adjacent to the designated pixel e1, and its distance from the designated pixel e1 is 1. This first surrounding pixel e2 is closer to the designated pixel e1 than the second surrounding pixel e3. However, since the approximate color of the first surrounding pixel e2 is either the same as the first color or the same as a color already added to the color list, it has been removed as a candidate for addition.

[0045] Pixel e No. 2 and pixel e No. 3 are second surrounding pixels e3 that sandwich surrounding pixels e2 and e3 between them and the designated pixel e1, and are at a distance of 2 or more from the designated pixel e1. The distance between the positions of the second surrounding pixel e3 No. 3 is 4, which is shorter than the distance between the positions of the second surrounding pixel e3 No. 2, which is 9. Therefore, the control device 50 sets the priority of the second surrounding pixel e3 No. 3 to 2, which is higher than the priority of the second surrounding pixel e3 No. 2, and sets the priority of the second surrounding pixel e3 No. 3 to 3. In other words, the control device 50 stores the priority of the second surrounding pixel e3 No. 3 in the memory unit 53 in the candidate list of FIG. 8 as 2, which is higher than the priority of the second surrounding pixel e3 No. 2, and stores the priority of the second surrounding pixel e3 No. 3 in the memory unit 53 as 3.

[0046] In this way, the number of second colors added to the color list is equal to or less than the upper limit set by the first setting operation. The second colors are colors between two first colors, are colors contained in image E, and include the designated color of designated pixel e1 designated by the user and colors similar to the surrounding pixels e2 and e3 of the designated pixel e1.

[0047] The control device 50 determines whether the addition operation has been performed for all designated pixels e1 specified in step S10 (step S20). If there are any designated pixels e1 for which the addition operation has not been performed (step S20: NO), the control device 50 performs a second setting operation (step S21). In the second setting operation, when multiple designated pixels e1 including a first designated pixel e1 are specified by the input device 14, the control device 50 sets the upper limit number of designated colors and similar colors to be added to the color list by the addition operation for the first designated pixel e1 according to the number of designated colors and similar colors added to the color list by the addition operation performed before the addition operation for the first designated pixel e1 among the multiple designated pixels e1. In other words, the control device 50 stores the upper limit numbers according to the number of designated colors and similar colors added to the color list by the addition operation performed before the addition operation for the first designated pixel e1 among the multiple designated pixels e1 in a predetermined storage area of ​​the storage unit 53.

[0048] Specifically, the upper limit number of designated colors and similar colors to be added as second colors to the color list is set for each designated pixel e1 in the first setting operation in step S11. However, the number of similar colors obtained in step S13 may be small. Furthermore, among the designated colors and designated colors, the number of colors determined to be the same as the first color in step S14 and the number of colors determined to be the same as colors already added in step S15 may be large. In such cases, the number of designated colors and their similar colors added in step S19 may be less than the upper limit number. Therefore, the control device 50 resets the upper limit number in the second setting operation to prevent the number of second colors from becoming too small.

[0049] In the second setting operation, the control device 50 calculates the number of second patches cm by subtracting the number of first patches bn and the number of specified colors and similar colors added in step S17 from the total number of patches.The control device 50 calculates the quotient of the number of second patches cm divided by the number of remaining specified pixels e1 as the upper limit number of specified colors and similar colors for each specified pixel e1.The control device 50 then stores the calculated upper limit number in a predetermined storage area of ​​the storage unit 53.

[0050] For example, suppose five designated pixels e1 are designated in step S10. The control device 50 sets the upper limit number for the first designated pixel e1 of the five designated pixels e1 in a first setting operation (step S11), and then executes the processes of steps S12-S20. The control device 50 then calculates the upper limit number of designated colors and similar colors for the second designated pixel e1 by dividing the difference between the addition number for the first designated pixel e1 in step S19 and the number of first patches bn from the total number of patches by four (the number of remaining designated pixels e1) (step S21).

[0051] The control device 50 performs the processes of steps S12-S20 for the second designated pixel e1. The control device 50 then calculates the upper limit number of designated colors and similar colors for the third designated pixel e1 by dividing the difference between the number of additions for the first designated pixel e1, the number of additions for the second designated pixel e1, and the number of first patches bn and the total number of patches by three (step S21). As with the second designated pixel e1, the control device 50 performs the processes of steps S12-S21 for the third and fourth designated pixels e1. The control device 50 then performs the processes of steps S12-S20 for the final, fifth designated pixel e1. Here, the control device 50 determines that the addition operation has been performed for all designated pixels e1 (step S20: YES), and returns to the process of step S4 in the flowchart of FIG. 3.

[0052] The control device 50 executes a printing operation of the patch chart D (step S4). Specifically, as shown in the example of Fig. 5, the patch chart D is an image representing patches of colors in the color list, and includes a plurality of first patches bn of the first patch group B and a plurality of second patches cm of the second patch group C.

[0053] For example, the first color of the first patch group B and the second color of the second patch group C are specified by RGB values. The printing device 10 then prints using four CMYK ink colors. In this case, the control device 50 reads the RGB values ​​of the first and second colors from the storage unit 53 and converts them to CMYK values ​​in the CMYK color space, which is the dependent color space of the printing device 10, based on a predetermined correspondence relationship, such as an ICC profile. The control device 50 then obtains image data for a patch chart D based on the CMYK values ​​and the patch sizes obtained in step S1, and prints the patch chart D in the printing area A1 of the printing medium A based on this image data. As a result, the first patch group B and the second patch group C are printed on the same printing medium A in the patch chart D corresponding to the color list.

[0054] Printing medium A, on which patch chart D is printed, has a first area Ab, in which first patch group B is printed, and a second area Ac, in which second patch group C is printed. For example, in printing area A1, a boundary line A2 is provided between first area Ab and second area Ac. Boundary line A2 extends in the front-to-back direction. As shown in the example of Figure 5, part of boundary line A2 may bend left and right. This part extending left and right corresponds to the left-to-right length of one patch.

[0055] The first area Ab is located to the left of the boundary line A2, and the second area Ac is located to the right of the boundary line A2. The first area Ab is a single closed area that includes all of the first patches bn in the first patch group B. The second area Ac is a single closed area that includes all of the second patches cm in the second patch group C. Thus, the printing area A1 has one boundary line A2, one first area Ab, and one second area Ac. In the first area Ab, the multiple first patches bn are arranged in the left-right direction and the front-back direction. In the second area Ac, the multiple second patches cm are arranged in the left-right direction and the front-back direction. In the printing area A1, the row of multiple first patches bn arranged in the left-right direction and the row of multiple second patches cm arranged in the left-right direction are arranged on the same straight line.

[0056] The control device 50 acquires colorimetric values ​​obtained by measuring the first color of the first patch bn and the second color of the second patch cm printed on the printing medium A using the colorimeter 15 (step S6). The colorimetric values ​​are expressed, for example, in Lab values. The Lab values ​​are device-independent L * a * b * The color values ​​are coordinate values ​​in a color space, where L represents lightness, and a and b represent hue and saturation in Cartesian coordinates. The control device 50 associates the RGB values ​​of the first color of the first patch bn and the second color of the second patch cm with their Lab values, which are colorimetric values, and stores them in a color list.

[0057] The control device 50 interpolates the first color in the color gamut of the printing device 10 (step S7). For example, the first color in the color list is an RGB value in 32 increments and a Lab value corresponding to the RGB value. Therefore, the control device 50 obtains the color gamut of the printing device 10 in increments smaller than the 32 increments of the first color, for example, an RGB value in 16 increments. The RGB value in 16 increments is (256 / 16+1) 3 = 4913 kinds of colors, and has 729 kinds of RGB values ​​of primary colors in 32-increment increments, and 4184 kinds of RGB values ​​of interpolated colors between these RGB values.

[0058] Since the second color is a color between two first colors, it is used as one of m of the 4,184 interpolation colors. However, if the RGB value of the second color is different from the RGB values ​​in 16-step increments, the control device 50 extracts the RGB value closest to the RGB value of the second color from the RGB values ​​of the interpolation colors, associates the Lab values ​​of the RGB value of the second color with that RGB value, and adds the extracted RGB value to the color list. The control device 50 obtains Lab values ​​based on the correspondence between the RGB values ​​and Lab values ​​of the first and second colors as Lab values ​​corresponding to the RGB values ​​of the remaining (4,184-m) interpolation colors, and adds the Lab values ​​to the color list. As a result, the color list includes the correspondence between the RGB values ​​and Lab values ​​of the first color, the correspondence between the RGB values ​​and Lab values ​​of the second color, and the correspondence between the RGB values ​​and Lab values ​​obtained based on the first and second colors. In this way, in the color list, colors between two first colors are interpolated using the second color and colors based on the first and second colors.

[0059] The control device 50 executes the creation operation (step S8). In the creation operation, the control device 50 creates a color calibration profile based on the color list for converting the colors of the image data into the colors of the image E to be printed by the printing operation so that the colors of the image E become the target colors. Here, the target colors are colors input to the control device 50 from the input device 14 and external devices, such as colors displayed on a computer display, and may be Lab values ​​corresponding to RGB values. For example, a user may input Lab values ​​corresponding to the RGB values ​​of the target color of the image E to be printed by the printing device 10 through the input device 14, and the control device 50 may acquire the Lab values ​​of the target color from the input device 14. The external device may also be an output device other than the printing device 10, such as a display or a printer. The control device 50 may acquire the Lab values ​​corresponding to the RGB values ​​of the target color from the external device through the interface 51.

[0060] Specifically, the control device 50 creates an RGB value conversion table that converts the RGB values ​​of the printing device 10 into the RGB values ​​of the target color so that the Lab values ​​of the target color match the Lab values ​​of the printing device 10 in the color list acquired in step S7. Furthermore, if the printing device 10 uses four ink colors (cyan, magenta, yellow, and black) for printing, the control device 50 creates a color calibration profile, which is a conversion table that converts the RGB values ​​of the target color in the RGB value conversion table into CMYK values ​​based on a predetermined correspondence relationship, and stores the color calibration profile in the storage unit 53. In this color calibration profile, the RGB values ​​of the image data corresponding to the RGB values ​​of the printing device 10 correspond to the CMYK values ​​of the printing device 10 so that the color of the image E printed by the printing operation matches the target color.

[0061] When the printing device 10 prints image E based on image data, the control device 50 converts the RGB values ​​of the image data into CMYK values ​​of the printing device 10 based on the color calibration profile. Then, the control device 50 prints image E on print medium A based on the CMYK values ​​of the converted image data. This makes it possible to match the colors of image E printed by the printing device 10 to target colors. For example, the color hue of image E printed by the printing device 10 based on image data that has been color-calibrated using the color calibration profile can match the color hue of image E output by another output device based on image data.

[0062] <Actions and Effects> In the printing device 10, the control device 50 executes a printing operation to print, on the same printing medium A, a first patch group B including a plurality of patches and a second patch group C including a patch corresponding to a specified pixel e1 specified by the input device 14, the second patch group C having a pair of patches with a smaller color difference than the pair of patches with the smallest color difference in the first patch group B. This allows the colors of the image data to be calibrated based on the colorimetric values ​​of the printed first patch group B and second patch group C. The second patch group C has a smaller color difference between patches than the first patch group B and includes a patch corresponding to the pixel e1 specified by the user. This makes it possible to improve the color calibration of an image E with a small color difference between pixels e, while taking into account the colors specified by the user.

[0063] In the printing device 10, the printing medium A has a first area Ab in which the first patch group B is printed, and a second area Ac in which the second patch group C is printed. This makes it easy for the user to check the second patch group C used for color proofing in the second area Ac.

[0064] In the printing device 10, the control device 50 executes an adding operation to add the second patch group C to the color list, and a creating operation to create a color calibration profile based on the color list for calibrating the colors of the image data so that the colors of image E become the target colors. This allows the colors of the image data to be calibrated using a color calibration profile based on a color list that has a small color difference and includes the specified color of the specified pixel e1. By printing image E based on the image data whose colors have been calibrated, image E can be printed in the target colors.

[0065] In the printing device 10, the adding operation includes a searching operation of searching for a color that is a color of a pixel e located around the designated pixel e1 in the image E and has a color difference from the designated color that is less than a threshold value. By adding the color of a pixel e around the designated pixel e1 and that has a small color difference from the designated color to the color list, it is possible to perform color calibration of the image E taking into account the colors around the designated pixel e1.

[0066] In the printing device 10, the pixels e located around the designated pixel e1 include pixels e adjacent to the designated pixel e1 in image E, and pixels e contiguous to the designated pixel e1 via pixels e of a color whose color difference from the designated color is less than a threshold value in image E. This allows for accurate extraction of a range of colors around the designated pixel e1 that have a small color difference from the designated color, and adding the colors in this surrounding range to a color list, thereby enabling color calibration of image E that takes into account the colors around the designated pixel e1.

[0067] In the printing device 10, after a search operation, the control device 50 executes an acquisition operation to acquire as an approximate color the color of pixel e located around the specified pixel e1 in image E, the color whose color difference from the specified color is less than a threshold, and an addition operation to determine whether the specified color and the approximate color differ from the colors of first patch group B. In the addition operation, of the specified color and the approximate colors, colors that differ from the colors of first patch group B are added to the color list. This allows as many colors as possible that differ from the colors of first patch group B to be added to the color list, thereby improving color proofing based on the color list.

[0068] In the printing device 10, after the search operation, the control device 50 executes an acquisition operation to acquire, as approximate colors, colors of pixels e located around the designated pixel e1 in the image E, whose color difference from the designated color is less than a threshold. If the acquisition operation acquires multiple approximate colors, the control device 50 performs an addition operation to add to the color list, preferentially, the approximate colors of pixels e that are closer to the designated pixel e1 among the multiple approximate colors. This allows for improved color calibration by taking into account surrounding colors close to the pixel e1 designated by the user.

[0069] In the printing device 10, the control device 50 executes a first setting operation to set an upper limit on the number of specified colors and similar colors to be added to the color list by the addition operation, based on the number of colors included in the first patch set B, the patch size, and the size of the printing area A1 of the printing medium A. This allows for the improvement of color proofing to be achieved as the number of colors added to the color list increases. However, the number of printing media A onto which patch charts D corresponding to the color list are printed and the number of patches to be printed increases, which requires more effort for color proofing. Therefore, by setting an upper limit on the number of colors that can be added, it is possible to appropriately balance the improvement of color proofing and the effort required.

[0070] <Modification> 7, in the search operation, the control device 50 acquires a region of pixels e in image E whose color difference from the designated color is less than a threshold, extracts a region including the designated pixel e1 from that region, and sets the color of the pixels e in that region as the approximate color. In contrast, the control device 50 may acquire, for each pixel e in a direction away from the designated pixel e1, pixels e whose color difference from the designated color is less than a threshold, as in the example of FIG. 9, and set the color of the pixel e as the approximate color.

[0071] Specifically, as shown in FIG. 9(a), the control device 50 acquires from the image data the designated color of a designated pixel e1 designated by the input device 14 in the image E displayed on the display device 13. The control device 50 acquires from the image data the colors of each of the four first surrounding pixels e2 (e21 to e24) adjacent to the designated pixel e1 in the x and y directions. The control device 50 acquires, as the approximate color, the color of the first surrounding pixel e2 of the four first surrounding pixels e2 whose color difference from the designated color is less than a threshold value. For example, if, among the four first surrounding pixels e21 to e24, the color of the first surrounding pixel e22 or e23 has a color difference from the designated color less than a threshold value, this color is acquired as the approximate color.

[0072] Next, as shown in FIG. 9(b), the control device 50 acquires from the image data the colors of the four pixels e adjacent to the first surrounding pixel e22 and the four pixels e adjacent to the first surrounding pixel e23. Of these adjacent pixels e, the control device 50 acquires pixels e whose color difference from the designated color is less than a threshold value. Of these pixels e, the control device 50 acquires the color of the second surrounding pixel e3, which is a pixel e other than the designated pixel e1 and the first surrounding pixel e2, as the approximate color. For example, of the second surrounding pixels e3, the colors of the three second surrounding pixels e31 are acquired as the approximate color.

[0073] 9(c), the control device 50 obtains the colors of the four pixels e adjacent to each of the three second surrounding pixels e31 from the image data. Of these adjacent pixels e, the control device 50 obtains pixels e whose color difference from the designated color is less than a threshold, and obtains the color of the second surrounding pixel e3, which is a pixel e other than the designated pixel e1 and the first surrounding pixel e2, as the approximate color.

[0074] In this way, the control device 50 sequentially searches for the colors of pixels e in image E that are adjacent to the designated pixel e1, the first surrounding pixel e2, and the second surrounding pixel e3, and finds pixels e whose color difference from the designated color is less than a threshold value, and repeatedly acquires the colors of the pixels e as approximate colors. By expanding a single closed range of approximate colors centered on the designated pixel e1, colors of pixels e with small color differences, such as gradations, can be added to the color list, thereby improving the color calibration of image E, where the color difference between pixels e is small.

[0075] It should be noted that all of the above embodiments may be combined with one another as long as they do not exclude one another. Furthermore, many improvements and other embodiments of the present invention will be apparent to those skilled in the art from the above description. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function of the present invention may be substantially changed without departing from the spirit of the present invention. [Industrial Applicability]

[0076] The present invention can be applied to a printing apparatus that can improve the color proofing of an image, a control method thereof, and a program. [Explanation of symbols]

[0077] 10:Printing device 14: Input device 20: Head 53: Storage section

Claims

1. a head that prints an image having a plurality of pixels on a printing medium based on image data; an input device capable of specifying pixels of the image; a storage unit that stores a color list including colors of a first patch group that includes patches of a plurality of colors whose color differences with each other are equal to or greater than a predetermined threshold; a control device; The control device an adding operation of adding to the color list the colors of a second patch group including the patch of a designated color that is the color of a designated pixel designated by the input device and the patch of an approximate color that has a color difference from the designated color that is less than the threshold; a printing operation of printing the first patch group and the second patch group on the same printing medium; and creating a color proofing profile based on the color list to convert the colors of the image data into the colors of the image printed by the printing operation so that the colors of the image become target colors.

2. 2. The printing device according to claim 1, wherein the print medium has a first area in which the first patch group is printed and a second area in which the second patch group is printed.

3. The printing device according to claim 1 or 2, wherein the additional operation includes a search operation for searching for a color of a pixel located around the designated pixel in the image, the color difference of which from the designated color is less than the threshold value.

4. 4. A printing device according to claim 3, wherein the pixels located around the designated pixel include pixels adjacent to the designated pixel in the image and pixels adjacent to the designated pixel via pixels in the image whose color difference from the designated color is less than the threshold.

5. The control device an acquisition operation of acquiring, after the search operation, a color of a pixel adjacent to the designated pixel in the image, or a color of a pixel adjacent to the designated pixel in the image via a pixel whose color difference from the designated color is less than the threshold, as the approximate color, and whose color difference from the designated color is less than the threshold; a determining operation for determining whether the specified color and the approximate color are different from the color of the first patch group in the adding operation; The printing device according to claim 3 , wherein in the adding operation, colors of the specified color and the similar colors that are different from the colors of the first patch group are added to the color list.

6. The control device After the search operation, an acquisition operation is performed to acquire, as the approximate color, a color of a pixel adjacent to the designated pixel in the image, or a color of a pixel adjacent to the designated pixel in the image via a pixel whose color difference from the designated color is less than the threshold value, and whose color difference from the designated color is less than the threshold value; A printing device according to any one of claims 3 to 5, wherein if multiple similar colors are acquired by the acquisition operation, in the addition operation, the similar color of a pixel that is closer to the specified pixel among the pixels corresponding to the multiple similar colors is preferentially added to the color list.

7. A printing device described in any one of claims 2 to 6, wherein the control device performs a first setting operation to set the upper limit number of the specified color and the approximate colors to be added to the color list by the adding operation based on the number of colors included in the first patch group, the size of the patch, and the size of the printing area of ​​the printing medium.

8. 8. The printing device of claim 7, wherein when a plurality of designated pixels including a first designated pixel are designated by the input device, the control device performs a second setting operation to set the upper limit number of the designated colors and the approximate colors to be added to the color list by the addition operation for the first designated pixel according to the number of the designated colors and the number of the approximate colors added to the color list by the addition operation performed before the addition operation for the first designated pixel among the plurality of designated pixels.

9. A control method for a printing device including a head that prints an image having a plurality of pixels on a printing medium based on image data, a storage unit that stores a color list including colors of a first patch group that includes patches of a plurality of colors whose color differences with each other are equal to or greater than a predetermined threshold, and an input device that can specify pixels of the image, an adding operation of adding to the color list the colors of a second patch group including the patch of a designated color that is the color of a designated pixel designated by the input device and the patch of an approximate color that has a color difference from the designated color that is less than the threshold; a printing operation of printing the first patch group and the second patch group on the same printing medium; and a creation operation of creating a color proofing profile based on the color list to convert the colors of the image data into the colors of the image printed by the printing operation so that the colors of the image become target colors.

10. A computer is provided with a head that prints an image having a plurality of pixels on a printing medium based on image data, a storage unit that stores a color list including colors of a first patch group that includes patches of a plurality of colors whose color difference with each other is equal to or greater than a predetermined threshold, and an input device that can specify pixels of the image. an adding operation of adding to the color list the colors of a second patch group including the patch of a designated color that is the color of a designated pixel designated by the input device and the patch of an approximate color that has a color difference from the designated color that is less than the threshold; a printing operation of printing the first patch group and the second patch group on the same printing medium; and a creating operation of creating a color proofing profile based on the color list for converting the colors of the image data into the colors of the image printed by the printing operation so that the colors of the image become target colors.

Images