Printing apparatus, its control method, and computer program

Abstract

To provide a printer which can improve color calibration of an image.SOLUTION: A printer 10 includes a first nozzle 24a, a second nozzle 24b, a first channel 13a, a second channel 13b, a display device 14 and a control device 50. The control device executes a first acquisition operation of acquiring an image color region being a region in a prescribed color space occupied by a color value included in image data, a second acquisition operation of acquiring a printing color region being a region in a color space occupied by a color value of printable colors of a first nozzle and a second nozzle by ink in a candidate color and ink in a fundamental color for the plurality of candidate colors that can be selected as a specific color, a third acquisition operation of acquiring an evaluation value when the printing color region is compared with the image color region for the plurality of candidate colors, and a first display operation of displaying on a display device the order of the candidate colors based on the evaluation value before the ink in the specific color is filled to the second channel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As a conventional printing apparatus, for example, the color processing apparatus described in Patent Document 1 is known. This color processing apparatus acquires an evaluation value for the difference between the image color values ​​of an image and a predetermined color gamut of an output device that outputs the image. If the evaluation value is greater than a predetermined threshold, the apparatus converts the image color values ​​to output color values ​​so that the image color values ​​fit within the color gamut of the output device. On the other hand, if the evaluation value is less than the predetermined threshold, the apparatus acquires the image color values ​​as output color values ​​without conversion. The apparatus then generates a color profile that associates the image color values ​​with the output color values ​​and performs color conversion processing of the image data based on this color profile. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2008-123291 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The above color processing device evaluates the difference between the image color values ​​and a predetermined color gamut of the output device, and performs color conversion based on this evaluation value. However, since the input color may not be reproducible within the predetermined color gamut, it is conceivable to use a different special color in the output device. In this case, the selection of a special color that improves image reproducibility is required.

[0005] In view of these circumstances, the present invention aims to provide a printing apparatus, a control method thereof, and a computer program that can improve the reproducibility of images using special colors. [Means for solving the problem]

[0006] A printing apparatus according to one aspect of the present invention includes: a first nozzle for printing an image on a printing medium based on image data using ink of a predetermined basic color; a second nozzle for printing an image on a printing medium based on image data using ink of a special color different from the basic color; a first channel for supplying the basic color ink to the first nozzle; a second channel for supplying the special color ink to the second nozzle; a display device; and a control device, wherein the control device performs: a first acquisition operation to acquire an image color gamut, which is the region occupied by the color values ​​included in the image data within a predetermined color space; a second acquisition operation to acquire a print color gamut for a plurality of candidate colors that can be selected as the special color, which is the region occupied by the color values ​​of the printable colors of the first and second nozzles using the ink of the candidate color and the ink of the basic color; a third acquisition operation to acquire an evaluation value when comparing the print color gamut and the image color gamut for a plurality of candidate colors; and a first display operation to display the ranking of the candidate colors based on the evaluation value on the display device before the special color ink is filled into the second channel.

[0007] A control method for a printing apparatus according to one aspect of the present invention comprises: a first nozzle for printing an image on a printing medium based on image data using a predetermined basic color ink; a second nozzle for printing an image on a printing medium based on image data using a special color ink different from the basic color; a first channel for supplying the basic color ink to the first nozzle; a second channel for supplying the special color ink to the second nozzle; and a display device, wherein the control method for a printing apparatus comprises: a first acquisition operation for acquiring an image color gamut, which is the region occupied by the color values ​​included in the image data within a predetermined color space; For a plurality of candidate colors that can be selected as special colors, the following operations are performed: a second acquisition operation to acquire a printable color gamut, which is the area in the color space occupied by the color values ​​of the printable colors of the first and second nozzles using the candidate color ink and the basic color ink; a third acquisition operation to acquire an evaluation value when comparing the printable color gamut and the image color gamut for a plurality of candidate colors; and a first display operation to display the ranking of the candidate colors based on the evaluation value on the display device before the second channel is filled with the special color ink.

[0008] A computer program according to one aspect of the present invention causes a printing apparatus comprising: a first nozzle for printing an image on a printing medium based on image data using a predetermined basic color ink; a second nozzle for printing an image on a printing medium based on image data using a special color ink different from the basic color; a first channel for supplying the basic color ink to the first nozzle; a second channel for supplying the special color ink to the second nozzle; and a display device, to perform the following operations: a first acquisition operation for acquiring an image color gamut, which is the region occupied by the color values ​​included in the image data within a predetermined color space; a second acquisition operation for acquiring a print color gamut, which is the region occupied by the color values ​​of the printable colors of the first and second nozzles using the candidate color inks and the basic color inks for a plurality of selectable special colors; a third acquisition operation for acquiring an evaluation value when comparing the print color gamut and the image color gamut for a plurality of the candidate colors; and a first display operation for displaying the ranking of the candidate colors based on the evaluation value on the display device before the special color ink is filled into the second channel. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a printing apparatus, a control method thereof, and a computer program that can improve the color calibration of images.

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

[0011] [Figure 1] Figure 1 is a schematic diagram of a printing apparatus according to an embodiment and a modified example of the present invention, viewed from above. [Figure 2] Figure 2 is a schematic diagram of the head viewed from below. [Figure 3] Figure 3 is a block diagram showing the functional configuration of a printing apparatus. [Figure 4] Figure 4 is a flowchart showing an example of a control method for a printing apparatus according to an embodiment. [Figure 5] Figure 5 shows the image data acquired by the first acquisition operation in Figure 4. [Figure 6] Figure 6 shows the color gamut of the image in Figure 5, represented in the L*a*b* color space. [Figure 7] Figure 7 shows the print color gamut of red represented in the L*a*b* color space. [Figure 8] Figure 8 shows the printable color gamut of green in the L*a*b* color space. [Figure 9] Figure 9 shows the image color gamut of the image in Figure 5 and the printed color gamut of red superimposed in the L*a*b* color space. [Figure 10] Figure 10 shows the image color gamut of the image in Figure 5 and the green print color gamut superimposed in the L*a*b* color space. [Figure 11] Figure 11 shows the ranking of candidate colors based on evaluation values, as displayed on a display device. [Figure 12] Figure 12 shows multiple images used for the image color gamut. [Figure 13] Figure 13 is a flowchart showing an example of a control method for a printing apparatus according to Modification 3. [Figure 14] Figure 14 shows the image data acquired by the first acquisition operation in Figure 13. [Figure 15] Figure 9 shows the image color gamut of the image in Figure 14 and the printed color gamut of red superimposed in the L*a*b* color space. [Figure 16] Figure 16 shows the result of the judgment in Figure 13 displayed on a display device. [Figure 17] Figure 17 is a flowchart showing an example of a control method for a printing apparatus according to Modification 4. [Figure 18] Figure 18 shows the image displayed by the second display operation in Figure 17. [Figure 19] Figure 19 is a flowchart showing an example of a control method for a printing apparatus according to Modification 5. [Figure 20] Figure 20 shows the image displayed by the fourth display operation in Figure 19. [Figure 21] Figure 21 is a flowchart showing an example of a control method for a printing apparatus according to Modification 6. [Figure 22] Figure 22 shows the image displayed by the fifth display operation in Figure 21. [Figure 23] Figure 23 is a flowchart showing an example of a control method for a printing apparatus according to Modification 7. [Figure 24] Figure 24 shows the image displayed by the sixth display operation in Figure 23. [Figure 25] Figure 25 is a flowchart showing an example of a control method for a printing apparatus according to Modification 8. [Figure 26] Figure 26 shows the image displayed by the seventh display operation in Figure 25. [Figure 27] Figure 27 is a flowchart showing an example of a control method for a printing apparatus according to modified example 9. [Figure 28] Figure 28 shows the image displayed by the eighth display operation in Figure 27. [Figure 29] Figure 29 is a schematic diagram of the printing apparatus according to modified example 10, viewed from the left. [Modes for carrying out the invention]

[0012] <Printing device configuration> A printing apparatus 10 according to one embodiment of the present invention, as shown in Figure 1, is a device that ejects ink from the nozzles 24 (Figure 2) of the head 20 onto a printing medium A, and prints an image C onto the printing medium A using the ink. Below, an example of applying the printing apparatus 10 to an inkjet printer will be described, but the printing apparatus 10 is not limited to this. The printing medium A is, for example, a sheet of paper or cloth.

[0013] The printing apparatus 10 is a serial head type and includes a plurality of heads 20, a platen 11, a plurality of tanks 12, a transport device 30, and a scanning device 40. The first direction in which the transport device 30 transports the printing medium A is referred to as the front-to-back direction. The second direction intersecting (e.g., perpendicular to) the first direction is referred to as the left-to-right direction. The direction intersecting (e.g., perpendicular to) the front-to-back direction and the left-to-right direction is referred to as the up-and-down direction. However, the arrangement of the printing apparatus 10 is not limited to this. The printing apparatus 10 may also be a line head type. In this case, the printing apparatus 10 does not include a scanning device 40, and the heads 20 do not move and have dimensions longer than the length of the printing area of ​​the printing medium A in the left-to-right direction.

[0014] The multiple heads 20 include a first head 21, a second head 22, and a third head 23. The platen 11 has a flat upper surface and defines the distance between the printing medium A placed on its upper surface and the lower surface of the head 20 provided opposite it. The tanks 12 are containers for storing ink, and their number is equal to or greater than the number of ink types. For example, the tanks 12 have four first tanks 12a, each storing one of four basic color inks, one or more second tanks 12b, each storing a spot color ink, and one or more third tanks 12c, each storing a base color ink.

[0015] Examples of basic ink colors include cyan, yellow, magenta, and black. Special inks are those of different colors from the basic inks, such as red, green, and blue. An example of a base color ink is white.

[0016] The first tank 12a stores the base color ink and is connected to the first head 21 via the first channel 13a. The base color ink is supplied from the first tank 12a to the first head 21 via the first channel 13a. The second tank 12b is connected to the second head 22 via the second channel 13b. When the special color ink is stored in the second tank 12b, the special color ink flows from the second tank 12b to the second channel 13b, fills it, and is supplied to the head 20. Before the special color ink is stored in this second tank 12b, it is filled with a preservative liquid different from the special color ink. The third tank 12c is connected to the third head 23 via the third channel 13c. The base color ink is supplied from the third tank 12c to the third head 23 via the third channel 13c. The first channel 13a, the second channel 13b, and the third channel 13c are, for example, rubber tubes or plastic tubes, and are preferably made of materials that are resistant to bending.

[0017] The conveying device 30 includes, for example, two sets of conveying rollers 31 and a conveying motor 32 (Figure 3). The two sets of conveying rollers 31 are arranged in the front-to-back direction with the platen 11 in between them. Each conveying roller 31 has an axis that extends in the left-to-right direction. Each set of conveying rollers 31 is arranged vertically with the printing medium A in between them. One of the conveying rollers 31 in each set is connected to the conveying motor 32. The conveying rollers 31 rotate around their axis when driven by the conveying motor 32, and convey the printing medium A in the front-to-back direction on the platen 11.

[0018] The scanning device 40 includes a carriage 41, two guide rails 42, a scanning motor 43, and an endless belt 44. The two guide rails 42 extend horizontally above the platen 11 so as to sandwich the head 20 between them in the front-rear direction. The carriage 41 mounts the head 20 and is supported by the two guide rails 42 so as to be movable in the left-right direction. The endless belt 44 extends horizontally 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 travels, and the carriage 41 reciprocates horizontally along the guide rails 42. This causes the carriage 41 to move the head 20 horizontally.

[0019] <Head> The carriage 41 is provided with a plurality of heads 20, as shown in Figure 2. The plurality of heads 20 include, for example, two first heads 21, two second heads 22, and two third heads 23. The two first heads 21 include a right first head 21 and a left first head 21, the two second heads 22 include a right second head 22 and a left second head 22, and the two third heads 23 include a right third head 23 and a left third head 23.

[0020] For example, the second head 22 on the right, the first head 21 on the right, and the third head 23 on the right are arranged in a row with spacing between them in the front-to-back direction, in this order from the front. The second head 22 on the left, the first head 21 on the left, and the third head 23 on the left are arranged in a row with spacing between them in the front-to-back direction, in this order from the front. These heads 20 are arranged in a staggered pattern such that the first head 21 on the right is positioned in front of the first head 21 on the left, the second head 22 on the right is positioned in front of the second head 22 on the left, and the third head 23 on the right is positioned in front of the third head 23 on the left. However, the arrangement of the first head 21, the second head 22, and the third head 23 is not limited to this.

[0021] Each head 20 has a flow path forming body and a plurality of nozzles 24, and the flow path forming body is composed of a laminate of a plurality of plates including a nozzle plate 27. The nozzle plate 27 has a flat plate shape, and its lower surface constitutes the lower surface of the head 20. The nozzles 24 open to the lower surface of the nozzle plate 27, which is the lower surface of the head 20. The plurality of nozzles 24 include a first nozzle 24a of the first head 21, a second nozzle 24b of the second head 22, and a third nozzle 24c of the third head 23. The plurality of nozzles 24 are arranged in a nozzle row in the front-to-back direction on each head 20. The plurality of nozzle rows are provided in parallel on each head 20 with spacing in the left-to-right direction. The nozzle row of the first head 21 has first nozzle rows 21a to 21d, the nozzle row of the second head 22 has second nozzle rows 22a to 22d, and the nozzle row of the third head 23 has third nozzle rows 23a to 23d.

[0022] The first nozzle 24a of the first nozzle row 21a is connected to the first tank 12a of cyan ink via the first channel 13a, and is capable of ejecting cyan ink. The first nozzle 24a of the first nozzle row 21b is connected to the first tank 12a of magenta ink via the first channel 13a, and is capable of ejecting magenta ink. The first nozzle 24a of the first nozzle row 21c is connected to the first tank 12a of yellow ink via the first channel 13a, and is capable of ejecting yellow ink. The first nozzle 24a of the first nozzle row 21d is connected to the first tank 12a of black ink via the first channel 13a, and is capable of ejecting black ink. The third nozzles 24c of the third nozzle rows 23a to 23d are connected to the third tank 12c of white ink via the third channel 13c, and are capable of ejecting white ink.

[0023] The second nozzles 24b of the second nozzle rows 22a to 22d are connected to the second tank 12b of the special color ink via the second channel 13b. When the special color ink is stored in the second tank 12b, the second nozzles 24b are supplied with the special color ink from the second tank 12b via the second channel 13b and become capable of dispensing the special color ink. Here, the second nozzles 24b of the second nozzle row 22a, the second nozzles 24b of the second nozzle row 22b, the second nozzles 24b of the second nozzle row 22c, and the second nozzles 24b of the second nozzle row 22d may dispensing different types of special color ink. For example, the second nozzle 24b of the second nozzle row 22a is capable of ejecting red ink, the second nozzle 24b of the second nozzle row 22b is capable of ejecting green ink, the second nozzle 24b of the second nozzle row 22c is capable of ejecting blue ink, and the second nozzle 24b of the second nozzle row 22d is capable of ejecting gold ink. Alternatively, the second nozzles 24b of the second nozzle row 22a, 24b of the second nozzle row 22b, 24b of the second nozzle row 22c, and 24b of the second nozzle row 22d may each eject ink of the same type. In this case, the printing apparatus 10 is provided with one type of second tank 12b, and the second nozzles 24b of the second nozzle rows 22a to 22d are connected to this second tank 12b, and each can eject ink of the same type.

[0024] Furthermore, as shown in Figure 3, the head 20 has a plurality of drive elements 25. The drive elements 25 are piezoelectric elements, heating elements, electrostatic actuators, etc., and are provided for each nozzle 24, applying pressure to the ink to eject the ink from the nozzle 24.

[0025] <Control devices, display devices, input devices> As shown in Figure 3, the printing device 10 further includes a display device 14, an input device 15, and a control device 50. The control device 50 is, for example, a computer and has an interface 51, an arithmetic unit 52, and a storage unit 53. The interface 51 receives various data, such as image data, from external devices B such as a computer, camera, communication network, recording medium, display, and printer. The image data is raster data showing an image C to be printed on a printing medium A. The control device 50 may consist of a single device, or multiple devices may be distributed and configured to cooperate in the operation of the printing device 10.

[0026] The storage unit 53 is a memory accessible from the arithmetic unit 52 and includes RAM and ROM. The RAM temporarily stores various types of data, such as data received from an external device B, such as image data, and data converted by the arithmetic unit 52. The ROM stores computer programs for various data processing tasks, and predetermined data such as predetermined correspondences. The computer programs may be stored on an external storage medium different from the storage unit 53 that is accessible from the arithmetic unit 52, such as a CD-ROM.

[0027] The arithmetic unit 52 includes, for example, a processor such as a CPU and at least one circuit such as an integrated circuit such as an ASIC. The arithmetic unit 52 controls each part by executing a computer program and performs various operations such as printing. Details of the various operations will be described later.

[0028] Such a control device 50 is electrically connected to the display device 14 and the input device 15. The display device 14 is, for example, a display, which displays an image C to be printed by a printing operation, under control by the control device 50. The input device 15 is, for example, a button and a mouse, which are operated by the user to input data to the control device 50. The input device 15 may be a touch panel integrated with the display device 14. The input device 15 may be an interface 51 to which information specifying the position on the display device 14 is input from an external source.

[0029] Furthermore, the control device 50 is electrically connected to the transport motor 32 of the transport device 30 via the transport drive circuit 33, and controls the drive of the transport motor 32. This controls the transport of the printing medium A by the transport device 30. In addition, the control device 50 is electrically connected to the scanning motor 43 of the scanning device 40 via the scanning drive circuit 46, and controls the drive of the scanning motor 43. This controls the movement of the head 20 by the scanning device 40.

[0030] Furthermore, the control device 50 is electrically connected to the drive element 25 via the head drive circuit 26. The control device 50 outputs a control signal for the drive element 25 to the head drive circuit 26, and the head drive circuit 26 generates a drive signal based on the control signal and outputs it to the drive element 25. The drive element 25 is driven in accordance with the drive signal, and ink is ejected from the nozzle 24.

[0031] <Printing operation> In such a printing apparatus 10, the control device 50 acquires image data of image C and executes a printing operation based on the image data. For example, the control device 50 moves the head 20 to the right or left in a path, ejecting ink from the head 20 onto the printing medium A. Then, the control device 50 transports the printing medium A forward in a transport operation. In this way, the printing apparatus 10 repeatedly performs the path and transport operations alternately, carrying out the printing operation to print image C onto the printing medium A with ink.

[0032] Here, if a background is printed on the printing medium A before printing image C, the control device 50 acquires the extent of the background based on the image data of image C so that image C is printed on the background. Then, the control device 50 ejects the background color ink from the third nozzle 24c of the third head 23 to form a background on the printing medium A with the background ink. Next, based on the image data of image C, the control device 50 ejects the basic color ink from the first nozzle 24a of the first head 21 and the spot color ink from the second nozzle 24b of the second head 22 to form image C on the background. As a result, image C is printed on the printing medium A via the background using the basic color and spot color inks.

[0033] <Control method for printing devices> The control method for the printing device 10 is performed by the control device 50 according to the flowchart shown in Figure 4, for example. For example, the control device 50 acquires image data of image C for printing image C in Figure 5 from an external device B (step S1). Image C has multiple pixels c0 divided per unit area. The image data includes the color value and position of the pixels c0. This color value is represented, for example, by color coordinates in a device-dependent color space, for example, by RGB values ​​in the RGB color space. This RGB value represents a single color by a combination of red color values ​​from 0 to 255, green color values ​​from 0 to 255, and blue color values ​​from 0 to 255.

[0034] Next, the control device 50 performs a first acquisition operation to acquire the image color gamut D, which is the region that the color values ​​contained in the image data of image C occupy in a predetermined color space (step S2). In the first acquisition operation, the control device 50 acquires the color value of pixel c0 in image C from the image data. Based on a predetermined correspondence between RGB values ​​and Lab values, the control device 50 converts the RGB value of pixel c0 to a Lab value. The Lab value is device-independent L * a * b * These are color values ​​in a color space, where L represents lightness, and a and b are Cartesian coordinates representing hue and saturation.

[0035] Then, as shown in FIG. 6, the control device 50 draws the image color value d, which is the Lab value of all the pixels c0 in the image C, in the L * a * b * color space. The control device 50, in this L * a * b * color space, acquires the area occupied by the Lab values of all the pixels c0 of the image C as the image color gamut D. The image color gamut D is a closed area in the L * a * b * color space and contains the image color value d of all the pixels c0 in the image C.

[0036] The image C in FIG. 5 has a pale orange part c1 of the face and hands, a light gray part c2 of the clothes, a dark gray part c3 of the clothes, a black part c4 of the hair and eyes, a red part c5 of the mouth and clothes, and a blue part c6 of the hairpin. In contrast, in the L * a * b * color space, the color gamuts d1 to d6, which are the areas of the color values of these parts c1 to c6, are arranged within the image color gamut D. The color gamuts d1 to d6 are a part of the image color gamut D, but are used more frequently in the image C than other color values in the image color gamut D. Therefore, in the image C, the pixels c0 having the color values of the color gamuts d1 to d6 are more numerous than the pixels c0 having other color values and occupy most of the parts. For example, the area of the parts using the color values of the parts c1 to c6 in the image C is almost equal to the total area of the image C. Thus, even if other color values are not represented by printing, it does not significantly affect the image quality of the printed image C. Therefore, hereinafter, the image color gamut D is processed as the color gamuts d1 to d6.

[0037] Subsequently, the control device 50 executes a second acquisition operation of acquiring the printing color gamuts Hr and Hg, which are the areas occupied by the color values of the colors that can be printed by the head 20 using the candidate color inks and the basic color inks, for a plurality of candidate colors that can be selected as features (step S3).

[0038] In the second acquisition operation, the control device 50 acquires the color values ​​of multiple candidate colors. The candidate colors are selections of spot colors of ink to be used to print image C. The color values ​​of the candidate colors may be input to the control device 50 via the input device 15 and interface 51, etc. Also, if the color values ​​of the candidate colors are already stored in the storage unit 53, the control device 50 may acquire the color values ​​of the candidate colors from the storage unit 53. For example, if the color value of the candidate color red is not stored in the storage unit 53, but the color value of the candidate color green is already stored in the storage unit 53, the control device 50 acquires the color value of red from the external device B via interface 51 and acquires the color value of green from the storage unit 53. The color values ​​of the candidate colors are represented, for example, by RGB values ​​or CMYK values, which are color coordinates in the device-dependent CMYK space. CMYK values ​​represent a single color by a combination of cyan, magenta, yellow, and black color values ​​of a predetermined gradation.

[0039] Furthermore, the control device 50 obtains the color values ​​of the basic colors from the storage unit 53. The basic colors are colors that can be printed by the printing device 10, and include single colors of ink provided by the printing device 10, as well as mixed colors thereof. For example, if the printing device 10 is equipped with cyan, magenta, yellow, and black inks, the basic colors include at least one of these four colors. The basic colors include single colors of cyan, magenta, yellow, and black, as well as mixed colors obtained by combining two or more of these colors. The color values ​​of the basic colors are stored in advance in the storage unit 53 and are expressed, for example, as CMYK values.

[0040] If the color values ​​of the candidate color and the base color are defined by RGB values, the control device 50 converts the RGB values ​​of the candidate color and the base color to Lab values ​​based on a predetermined correspondence between RGB values ​​and Lab values. If the color values ​​of the candidate color and the base color are defined by CMYK values, the control device 50 converts the CMYK values ​​of the candidate color and the base color to Lab values ​​based on a predetermined correspondence between CMYK values ​​and Lab values.

[0041] As shown in Figures 7 and 8, the control device 50 sets the basic color value f0, which is the Lab value of a plurality of basic colors, to L * a * b * It draws in the color space. The control device 50 controls this L * a * b * The region occupied by the Lab values ​​of all basic colors in the color space is obtained as the basic color gamut F0. The basic color gamut F0 is L * a * b * It is a closed region in the color space that contains all the fundamental color values ​​f0.

[0042] Furthermore, as shown in Figure 7, the control device 50 sets the candidate color value fr, which is the Lab value of the candidate red color, to L * a * b * The drawing is performed in the color space. Then, the control device 50, based on the basic color gamut F0 and candidate color values ​​fr, L * a * b * In the color space, the area extended from the base color by the candidate red color is acquired as the red extended color gamut Fr. This red extended color gamut Fr is, for example, the space enclosed by a straight line drawn from the candidate color value fr to the base color gamut F0, and the base color gamut F0, and is the largest space within this space. The colors of the red extended color gamut Fr include the single color of the candidate red color and mixed colors that combine the base color and the candidate red color. The control device 50 then acquires the combined area of ​​the base color gamut F0 and the red extended color gamut Fr as the red printing color gamut Hr. This red printing color gamut Hr is the color value of the colors that the head 20 can print with the ink of the candidate red color and the ink of the base color, in a predetermined color space, for example, L * a * b * It is a region within the color space.

[0043] Furthermore, as shown in Figure 8, the control device 50 sets the candidate color value fg, which is the Lab value of the green candidate color, to L * a * b * The drawing is performed in the color space. Then, the control device 50, based on the basic color gamut F0 and candidate color values ​​fg, L* a * b * In the color space, the area extended from the base color by the candidate green color is acquired as the green extended color gamut Fg. This green extended color gamut Fg is, for example, the space enclosed by a straight line drawn from the candidate color value fg to the base color gamut F0, and the base color gamut F0, and is the largest space within this space. The colors of the green extended color gamut Fg include the single green candidate color and mixed colors that combine the base color and the green candidate color. The control device 50 then acquires the area combining the base color gamut F0 and the green extended color gamut Fg as the green printing color gamut Hg. This green printing color gamut Hg is the area in the predetermined color space where the color values ​​of colors that the head 20 can print with the green candidate color ink and the base color ink occupy.

[0044] Next, the control device 50 performs a third acquisition operation (step S4) to obtain evaluation values ​​for multiple candidate colors when comparing the print color gamuts Hr and Hg with the image color gamut D. For example, the evaluation value may include the ratio of the area of ​​the portion of the total area of ​​the image C that corresponds to the image color gamut D included in the print color gamuts Hr and Hg.

[0045] In the third acquisition operation, the control device 50 acquires the image color value d of all pixels c0 in image C from the image data and determines whether or not the image color value d is included in the red printing color gamut Hr. The control device 50 acquires the total number Ir of pixels c0 in image C whose image color value d is included in the red printing color gamut Hr, and acquires the ratio Ir / Ic, the ratio of the total number of pixels c0 in the printing color gamut Hr to the total number of pixels c0 in image C Ic, as an evaluation value.

[0046] In the example in Figure 9, L * a * b *In the color space, the color gamut d1 to d6, which is the region of color values ​​c1 to c6 within the image color gamut D, is included in the red printing color gamut Hr. Therefore, almost all pixels c0 of image C have image color values ​​d within the printing color gamut Hr. The ratio Ir / Ic of the area of ​​the total area of ​​image C that corresponds to the image color gamut D included in the printing color gamut Hr is approximately 100%. In this case, the evaluation value is 100%. For example, if red is used as a candidate color, the color of image C can be reproduced by printing with the printing device 10 using the basic color and red ink.

[0047] Furthermore, the control device 50 obtains the image color value d of all pixels c0 in image C from the image data and determines whether or not the image color value d is included in the green printing color gamut Hg. The control device 50 obtains the total number Ig of pixels c0 in image C whose image color value d is included in the green printing color gamut Hg, and obtains the ratio Ig / Ic, the ratio of the total number of pixels c0 in the printing color gamut Hg to the total number of pixels c0 in image C Ic, as an evaluation value.

[0048] In the example in Figure 10, L * a * b * In the color space, the color gamuts d1-d4 of parts c1-c4 and d6 of part c6 within the image color gamut D are included in the green printing color gamut Hg, but the color gamut d5 of part c5 is not included in the printing color gamut Hg. Therefore, among the pixels c0 of image C, the pixel c0 of part c5 does not have an image color value d within the printing color gamut Hg, while the pixels c0 of parts c1-c4 and part c6 have an image color value d within the printing color gamut Hg. The ratio Ig / Ic of the area of ​​the portion of the total area of ​​image C that corresponds to the image color gamut D included in the printing color gamut Hg is, for example, 95%. In this case, the evaluation value is 95%. For example, if green is used as a spot color for the candidate color, the color of the pixel c0 of part c5 in image C cannot be reproduced by printing with the printing device 10 using the basic color and green ink.

[0049] Next, the control device 50 performs a first display operation (step S5) to display the ranking of candidate colors based on evaluation values ​​on the display device 14 before the second channel 13b is filled with the special color ink. In the first display operation, the control device 50 ranks the candidate colors in descending order of the evaluation values ​​obtained in step S4, stores the candidate colors, evaluation values, and rankings in the storage unit 53, and displays them on the display device 14 as shown in the list in Figure 11. The user can view the rankings of the multiple candidate colors and select a special color to be used for printing image C from among the multiple candidate colors. Then, when the user stores the ink of that special color in the second tank 12b, the special color ink is filled into the second channel 13b and supplied to the nozzles 24 of the second nozzle rows 22a to 22d in the second head 22. This makes it possible to improve the reproducibility of image C by using special colors in addition to basic colors.

[0050] <Example 1> In the printing apparatus 10 according to Modification 1, in the above embodiment, the image color gamut D includes the color values ​​of the image data of a plurality of images C. For example, as shown in Figure 12, image C includes a first image Ca, a second image Cb, and a third image Cc. In step S1 of Figure 4, the control device 50 acquires the image data of the first image Ca, the image data of the second image Cb, and the image data of the third image Cc from an external device B.

[0051] In the first acquisition operation of step S2 in Figure 4, the control device 50 acquires the color value of the first image Ca from the image data of the first image Ca, the color value of the second image Cb from the image data of the second image Cb, and the color value of the third image Cc from the image data of the third image Cc. Then, the control device 50 sets the image color value d, which is all the color values ​​in the first image Ca, the second image Cb, and the third image Cc, to L * a * b * It is drawn in the color space. Then, the control device 50 controls this L * a * b * In the color space, the region occupied by all image color values ​​d of the first image Ca, the second image Cb, and the third image Cc is obtained as the image color gamut D. The image color gamut D is L * a* b * A closed region in the color space that includes the image color value d of all pixels c0 in the first image Ca, the second image Cb, and the third image Cc. By forming an image color gamut D using image data from multiple images Ca, Cb, and Cc in this way, it is possible to improve the reproducibility of a wide range of images C.

[0052] <Modification 2> In the printing apparatus 10 according to Modification 2, in the above embodiment and Modification 1, the evaluation value includes the ratio of the volume Jr and Jg of the image color gamut D contained in the print color gamut Hr and Hg to the volume Jc of the image color gamut D in the color space.

[0053] In the third acquisition operation of step S4 in Figure 4, the control device 50 operates as shown in Figure 9, L * a * b * The volume Jc of the image color gamut D of image C in the color space is obtained based on the image color value d. In addition, the control device 50 L * a * b * The control device 50 obtains the volume Jr of the region where the image color gamut D and the red print color gamut Hr overlap in the color space, based on the image color value d, the basic color, and the candidate color color values. The control device 50 obtains the ratio Jr / Jc of the volume Jr of the image color gamut D within the print color gamut Hr to the volume Jc of the image color gamut D as an evaluation value. In addition, as shown in Figure 10, the control device 50 L * a * b * The control device 50 obtains the volume Jg of the region where the image color gamut D and the green print color gamut Hg overlap in the color space, based on the image color value d, the basic color, and the candidate color color values. The control device 50 obtains the ratio Jg / Jc, which is the ratio of the volume Jg of the image color gamut D within the print color gamut Hg to the volume Jc of the image color gamut D, as an evaluation value.

[0054] Then, in the first display operation of step S5 in Figure 4, the control device 50 displays the ranking of candidate colors based on the evaluation value on the display device 14 before the spot color ink is filled into the second channel 13b. This makes it possible to improve the reproducibility of image C by using spot colors in addition to basic colors.

[0055] <Variation 3> In the printing apparatus 10 according to Modification 3, in the above embodiment and Modifications 1-2, the image color gamut D includes a first color gamut which is the region in a predetermined color space in the image data of the first portion of the image C that has a size of a predetermined size or larger and a color value greater than or equal to a predetermined color difference from the surrounding color values. The control device 50 performs a determination operation to determine whether or not the first color gamut is included in the printing color gamut. If the control device 50 determines that the first color gamut is included in the printing color gamut, in the first display operation, it displays the first determination result of the determination operation in addition to the ranking of candidate colors on the display device 14.

[0056] For example, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 13, for example. In this flowchart of Figure 13, steps S6 and S7 are executed between steps S4 and S5 in the flowchart of Figure 4.

[0057] Specifically, the control device 50 acquires image data of image C in Figure 14 (step S1). This image C has parts c1 to c6, in addition to part c7 of a green pendant. The control device 50 L * a * b * In the color space, the first acquisition operation in step S2 acquires the image color gamut D of image C. As shown in Figure 15, the color gamut d7, which is the region of the color values ​​of part c7, is included within the image color gamut D. In addition, the control device 50 acquires the print color gamuts Hr and Hg of the candidate color in the second acquisition operation in step S3, and acquires evaluation values ​​of the print color gamuts Hr and Hg and the image color gamut D in the third acquisition operation in step S4.

[0058] The control device 50 determines whether the first part is included in the image C (step S6). The size of this first part is greater than or equal to a predetermined size. The predetermined size is a size that allows a person to perceive the image C from a predetermined distance away from the image C. For example, as shown in Figure 14, it is a size that encloses a circle k with a diameter k1 that is 2 or more cycles long and 6 or less in length within a 1° field of view from the distance at which a printed image C is normally observed. Thus, a first part that is larger than or equal to the predetermined size may not be large in size, but it is visible to a person and can therefore be an important part of the image C.

[0059] The first part has multiple pixels c0. Among the image color values ​​d of the multiple pixels c0 in the first part, the color difference between the smallest image color value d and the largest image color value d is less than or equal to a first predetermined color difference. For example, the color difference is L * a * b * In color space, when Lab values ​​are represented by color coordinates, they are expressed as inter-color distances, which are the distances between two color coordinates. The first predetermined color difference is the color difference at which two colors are perceived as the same color, for example, △E=5. Thus, the first portion where the color difference is less than or equal to the first predetermined color difference is the portion that can be recognized as the same color.

[0060] Furthermore, as shown in the example in Figure 14, the color difference between the image color value d of pixel c01, which is pixel c0 in the first part, and the image color value d of the surrounding pixel c02, which is pixel c0 adjacent to pixel c01, is greater than or equal to the second predetermined color difference. The surrounding pixel c02 is a pixel c0 in the first part that is adjacent to the pixel c01 that constitutes the outline of the first part. No other pixels c0 are interposed between the pixel c01 of the outline of the first part and the surrounding pixel c02. The second predetermined color difference is the color difference that makes the two colors appear different to each other, for example, △E=10. Thus, the first part whose color difference from its surroundings is greater than or equal to the second predetermined color difference is a part that can be distinguished from its surroundings.

[0061] In this determination, first, the control device 50 removes high-frequency components on the spatial frequency range that are indistinguishable to the human eye from the image data of image C, and then removes high-frequency components of approximately 6 cycles or more within a 1° field of view from the distance at which printed image C is normally observed. This removal of high-frequency components is performed using, for example, a low-pass filter and a two-dimensional Fourier transform. Then, the control device 50 obtains the image color value d and position of pixel c0 in image C from the image data. Pixel c0 is arranged in the x-direction and the y-direction intersecting (e.g., orthogonal to) the x-direction in image C. The position of pixel c0 is determined by its position in the x-direction and y-direction from a predetermined position in image C.

[0062] The control device 50 extracts a range of pixels c0, for example, a portion c7, where the color difference between the maximum color value and the minimum color value is less than or equal to a first predetermined color difference. The control device 50 then obtains the color difference between the image color value d of the pixels c0 in the extracted portion c7 and the image color value d of the surrounding pixels c02 adjacent to pixels c0 in portion c7 outside of portion c7, and determines whether the color difference is greater than or equal to a second predetermined color difference. The control device 50 then obtains the dimensions of portion c7 based on the position of the pixels c0 and determines whether these dimensions enclose a circle k with diameter k1. If the size of portion c7 is greater than or equal to a circle k, the control device 50 determines that portion c7 is the first portion (Step S6: YES).

[0063] Next, if it is determined that part c7 is the first part (step S6: YES), the control device 50 will L * a * b * In the color space, it is determined whether the first color gamut d7 of part c7 is included in the printing color gamuts Hr and Hg of the candidate color (step S7). In this determination operation, in the example of Figure 15, the control device 50 compares the first color gamut d7 with the printing color gamuts Hr and Hg and determines that the first color gamut d7 is not included in the red printing color gamut Hr but is included in the green printing color gamut Hg.

[0064] Next, in the first display operation of step S6, if the control device 50 determines that the image C contains the first part, it displays the evaluation value and the determination result of step S7 on the display device 14 as shown in Figure 16 before the second flow path 13b is filled with the spot color ink. In the example of Figure 16, the first color gamut d7 of the first part, c7, is not included in the red printing color gamut Hr, so the determination result is displayed as "×", and the first color gamut d7 is included in the green printing color gamut Hg, so the determination result is displayed as "〇". This allows the user to select a spot color to be used for printing image C from among multiple candidate colors, taking into account the determination result of the first part, which is important in image C, in addition to the ranking of the candidate colors, thereby improving the reproducibility of image C. Note that for the candidate color red, whose first color gamut d7 is not included in the printing color gamut Hr, the ranking and determination result do not need to be displayed on the display device 14 in the first display operation.

[0065] <Modification 4> In the printing apparatus 10 according to Modification 4, as in the above embodiment and Modifications 1 to 3, the control device 50 performs a second display operation to display the image C on the display device 14 in such a way that it distinguishes between the portion of the image C corresponding to color values ​​in the region of the image color gamut D that is not included in the printing color gamuts Hr and Hg, and the portion of the image C corresponding to color values ​​in the region of the image color gamut D that is included in the printing color gamuts Hr and Hg.

[0066] Here, the control device 50 may perform a conversion process to convert the color value d of the region of the image color gamut D that is not included in the print color gamut Hg to another color value d. In this case, the display device 14 displays the portion of the image C corresponding to the color value d of the region of the image color gamut D that is not included in the print color gamut Hg, based on the other color value d. The display device 14 displays the portion of the image C corresponding to the color value d of the region of the image color gamut D that is included in the print color gamut Hg without performing a conversion process.

[0067] For example, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 17, which is an example of a control method. In this flowchart of Figure 17, the control device 50 executes steps S8 and S9 after step S5 in the flowchart of Figure 4.

[0068] Specifically, for example, a user may see the ranking of candidate colors in the first display operation in step S5 and wish to see a detailed display. In this case, the control device 50 displays a detailed display button on the display device 14 for each candidate color, as shown in Figures 11 and 16. For example, when a user uses the input device 15 to move the cursor to the position of the detailed display button and makes a confirmation input, the control device 50 determines to display the detailed information corresponding to the candidate color (step S8: YES).

[0069] For example, when a detailed display is input (step S8: YES), the control device 50 performs a second display operation (step S9). For example, when a detailed display of a candidate color for red is input, the control device 50 extracts the image color values ​​d that are not included in the red printing color gamut Hr from the image color gamut D, as shown in Figure 9. In the example in Figure 5, the image color values ​​d of almost all pixels c0 of image C are included in the printing color gamut Hr. In this case, for pixels c0 with image color values ​​d within the printing color gamut Hr, the control device 50 displays image C on the display device 14 as shown in Figure 18(a), without converting the image color values ​​d of the image data to other color values. This allows the user to easily recognize that all of image C is included in the printing color gamut Hr by looking at this display, and to select a spot color from the candidate colors to improve the reproducibility of image C.

[0070] Furthermore, for example, when detailed display of a candidate color for green is input, the control device 50 extracts the image color value d of color gamut d5, which is not included in the green printing color gamut Hg, from the image color value d of the image color gamut D, as shown in Figure 10. In this case, the image color value d of color gamut d5 is not included in the printing color gamut Hg. The control device 50 does not perform a conversion process for the image color value d included in the printing color gamut Hg, and does not convert the image color value d of the image data to other color values. On the other hand, the control device 50 performs a conversion process for the image color value d of color gamut d5, which is not included in the printing color gamut Hg, and converts the image color value d of the image data to a different color value. Then, as shown in Figure 18(b), the control device 50 displays the image C, which has been converted from the image color value d of color gamut d5, on the display device 14. For example, on the display device 14, the mouth and clothing parts c5 of image C, which correspond to color gamut d5 that is not included in the printing color gamut Hg, are displayed with a different color value than the image color value d of color gamut d5. For example, in section c5, a different display format is used, such as a shading display using diagonal lines of white and blue. Also, in the display device 14, the portion of image C corresponding to the image color value d included in the print color gamut Hg is displayed using that image color value d. As a result, section c5 of image C is displayed separately from the rest of the image. Therefore, by looking at this display, the user can easily recognize that section c5 is not included in the print color gamut Hg and select a spot color from the candidate colors to improve the reproducibility of image C.

[0071] <Modification 5> In the printing apparatus 10 according to Modification 5, as in the above embodiment and Modifications 1 to 4, the control device 50 performs a third display operation in which it displays a color space representing the image color gamut D on the display device 14. The control device 50 performs a fourth display operation in which it displays on the display device 14 the color difference between the color value of the image C corresponding to the position in the color space specified by the input device 15 and the print color gamuts Hr and Hg.

[0072] For example, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 19, which is an example of a control method. In this flowchart of Figure 19, the control device 50 executes steps S10 and S11 in place of step S9 in the flowchart of Figure 17.

[0073] Specifically, for example, when a detailed display corresponding to a candidate color is input by the input device 15 (step S8: YES), the control device 50 performs a third display operation (step S10). In the third display operation, as shown in Figure 20, the control device 50 displays L representing the image color value d of the image color gamut D acquired in the first acquisition operation of step S2. * a * b * The color space is displayed on the display device 14. The user moves the arrow cursor m displayed on the display device 14 using the input device 15, L * a * b * The cursor m is positioned at the image color value d in the color space, and its position is input to the control device 50.

[0074] The control device 50 performs a fourth display operation (step S11). In the fourth display operation, the control device 50 obtains the image color value d of the color gamut d5 corresponding to the input position. If a detailed display of a candidate color for red is input, the color gamut d5 is included in the print color gamut Hr, so the control device 50 displays the color difference between the image color value d of color gamut d5 and the print color gamut Hr as "△E=0" on the display device 14. As a result, the user can easily recognize that the input image color value d is included in the print color gamut Hr by looking at this display, and can select a spot color from the candidate colors to improve the reproducibility of image C.

[0075] Furthermore, if a detailed display of a candidate green color is entered, the color gamut d5 is not included in the green print color gamut Hg. The control device 50 obtains the color difference between the image color value d of color gamut d5 and the print color gamut Hg. If the image color value d of color gamut d5 is outside the print color gamut Hg, L * a * b *In the color space, the color difference may be defined as the length of the perpendicular line drawn from the image color value d to the print color gamut Hg. Alternatively, the color difference may be defined as the shortest length between the image color value d and the print color gamut Hg. The control device 50 then displays this color difference as "△E=10" on the display device 14. This allows the user to easily recognize that the input image color value d is not included in the print color gamut Hg, and to recognize the color difference between the image color value d and the print color gamut Hg, thereby improving the reproducibility of image C by selecting a spot color from the candidate colors.

[0076] <Variation 6> In the printing apparatus 10 according to Modification 6, as in the above embodiment and Modifications 1 to 5, the control device 50 performs a fifth display operation in which a label n is displayed at the contour positions of the print color gamuts Hr and Hg, expressing that the color difference with the image color gamut D increases as the distance from the contour position outward from the print color gamut increases by changing at least one of hue, lightness, and saturation.

[0077] For example, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 21, which is an example of the control method. In this flowchart of Figure 21, the control device 50 executes the process of step S12 instead of step S9 in the flowchart of Figure 17.

[0078] Specifically, for example, when a detailed display corresponding to a candidate color is input by the input device 15 (step S8: YES), the control device 50 executes a fifth display operation (step S12). In the fifth display operation, if a detailed display of a candidate color for green is input, the control device 50 displays, as shown in Figure 22, the image color gamut D acquired in the first acquisition operation in step S2, and L representing the green print color gamut Hg acquired in the second acquisition operation in step S3. * a * b * The color space is displayed on the display device 14.

[0079] And the control device 50 is L * a * b *In the color space, an out-of-gamut color value, which is a Lab value outside the printing color gamut Hg, is obtained, and the color difference between the out-of-gamut color value and the printing color gamut Hg is obtained. At the contour position of the printing color gamut Hg, there is no color difference, and ΔE = 0. On the other hand, outside the printing color gamut Hg, the color difference increases as the distance from the contour position of the printing color gamut Hg increases. A label n representing this color difference is L * a * b * displayed in the color space. One end of the label n is connected to the contour of the printing color gamut Hg, and it extends in the direction away from the printing color gamut Hg. In the example of FIG. 22, in the label n, as the color difference increases, the lightness changes to be higher, and the label n is closer to white. Thereby, the user can easily recognize the color difference between the image color gamut D and the printing color gamut Hg by looking at the display of the label n, and can select a feature color from the candidate colors to improve the reproducibility of the image C. Note that the label n changes at least one of hue, lightness, and chroma according to the color difference.

[0080] Also, when a detailed display of the red candidate color is input, the control device 50 represents the image color gamut D obtained in the first acquisition operation in step S2 and the red printing color gamut Hr obtained in the second acquisition operation in step S3 in L * a * b * color space on the display device 14. Then, the control device 50 * a * b * obtains the color difference between the out-of-gamut color value outside the printing color gamut Hr and the printing color gamut Hr in the color space, and displays a label n representing this color difference in L * a * b * color space. Thereby, the user can easily recognize the color difference between the image color gamut D and the printing color gamut Hg by looking at the display of the label n, and can select a feature color from the candidate colors to improve the reproducibility of the image C.

[0081] <Modified Example ⑦> In the printing apparatus 10 according to Modification 7, as in the above embodiment and Modifications 1 to 6, the control device 50 performs a sixth display operation in which it displays the image C on the display device 14 by replacing the colors of each pixel c0 in the image C that are outside the printing color gamut Hr and Hg with colors whose hue, brightness, and saturation are changed according to the color difference with the printing color gamut Hr and Hg.

[0082] In this sixth display operation, for example, the control device 50 may replace the colors of each pixel c0 in the image C that are within the print color gamut Hr and Hg with a single color different from the color that replaces the colors outside the print color gamut Hr and Hg, and then display the image C on the display device 14.

[0083] In this case, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 23, which is an example of the control method. In the flowchart of Figure 23, the control device 50 executes the process of step S13 instead of step S9 in the flowchart of Figure 17.

[0084] Specifically, for example, when a detailed display corresponding to a candidate color is input by the input device 15 (step S8: YES), the control device 50 performs a sixth display operation (step S13). In the sixth display operation, if a detailed display of a candidate color of green is input, the control device 50 acquires the color difference between the image color gamut D acquired in the first acquisition operation in step S2 and the green print color gamut Hg acquired in the second acquisition operation in step S3. The control device 50 converts the image color value d of the image color gamut D into a color value corresponding to the color difference. For example, the control device 50 converts the image color value d into a color value where the brightness increases as the color difference increases.

[0085] In the example shown in Figure 10, color gamut d5 of the image color gamut D is not included in the print color gamut Hg, while the other color gamuts are included in the print color gamut Hg. In this case, since the color difference between the image color value d in color gamut d5 and the print color gamut Hg is greater than 0, the control device 50 converts the color value to a color value closer to white, where the brightness increases as the color difference increases. Also, there is no color difference between the image color value d outside of color gamut d5 and the print color gamut Hg, so △E=0. For this reason, the control device 50 converts this image color value d to a color value of black, where the brightness is low. Then, as shown in Figure 24(a), the control device 50 displays the image C on the display device 14 based on the image data obtained by converting the image color value d.

[0086] In the example shown in Figure 24(a), the portion c5 in image C, which corresponds to the color gamut d5, is displayed in a color brighter than black. On the other hand, the portion of image C other than c5 is displayed in black. By representing the color difference in brightness in image C in this way, the user can easily recognize the color difference between the image color gamut D and the print color gamut Hg, and select a spot color from the candidate colors to improve the reproducibility of image C. Note that in image C, at least one of the hue, brightness, and saturation is changed according to the color difference.

[0087] Furthermore, if detailed display of a candidate color for red is input, the control device 50 acquires the color difference between the image color gamut D acquired in the first acquisition operation in step S2 and the red print color gamut Hr acquired in the second acquisition operation in step S3. The control device 50 converts the image color value d of the image color gamut D into a color value corresponding to the color difference. In the example in Figure 9, the image color gamut D is included in the print color gamut Hr, and △E=0. Therefore, as shown in Figure 24(b), the control device 50 converts the image color value d of the image color gamut D into a color value of black with low brightness, and displays image C on the display device 14 based on the image data from which the image color value d has been converted. In the example in Figure 24(b), all parts of image C are displayed in black. In this way, by representing the color within the print color gamut Hr in image C as a single color different from the color that replaces the color outside the print color gamut Hr, the user can easily recognize the color difference between the image color gamut D and the print color gamut Hr, select a spot color from the candidate colors, and improve the reproducibility of image C.

[0088] <Differentiation Example 8> In the printing apparatus 10 according to the modified example 8, in the above embodiment and modified examples 1 to 7, the control device 50 performs a seventh display operation in which a patch chart P is displayed on the display device 14, in which patches p corresponding to each color value included in the image C are arranged on a plane, in order to distinguish patches p corresponding to color values ​​not included in the printing color gamut Hr and Hg from patches p corresponding to color values ​​included in the printing color gamut Hr and Hg.

[0089] In this case, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 25, which is an example of the control method. In the flowchart of Figure 25, the control device 50 executes the process of step S14 instead of step S9 in the flowchart of Figure 17.

[0090] Specifically, for example, when detailed display corresponding to a candidate color is input by the input device 15 (step S8: YES), the control device 50 performs the seventh display operation (step S14). In the seventh display operation, if detailed display of a candidate color for red is input, the control device 50 determines whether each of the multiple image color values ​​d in the image color gamut D acquired in the first acquisition operation of step S2 is included in the red printing color gamut Hr acquired in the second acquisition operation of step S3. Then, as shown in Figure 26(a), the control device 50 displays the mark q of the determination result along with the patch chart P of the patch p of the image color value d on the display device 14. If detailed display of a candidate color for green is input, the control device 50 determines whether each of the multiple image color values ​​d in the image color gamut D acquired in the first acquisition operation of step S2 is included in the green printing color gamut Hg acquired in the second acquisition operation of step S3. Then, as shown in Figure 26(b), the control device 50 displays the mark q of the judgment result along with the patch chart P of the patch p of the image color value d on the display device 14.

[0091] Patch p is a color swatch representing an image color value d, and for example, it has a rectangular shape. The patch chart P has the same number of patches p as there are image color values ​​d included in the image color gamut D, and these patches p are arranged on the same plane. As a result of the determination, for example, for image color values ​​d that are not included in the print color gamut Hr, a mark q such as "×" is used on the patch p. In this way, the user can see a list of image color values ​​d included in the image color gamut D using the patch chart P, and can easily recognize whether or not the image color value d is included in the print color gamuts Hr and Hg using the mark q. Therefore, the user can select a spot color from the candidate colors and improve the reproducibility of the image C.

[0092] <Modification 9> In the printing apparatus 10 according to Modification 9, as in the above embodiment and Modifications 1 to 8, the control device 50 performs a color compression operation to convert the color values ​​of image C to the color values ​​of the print color gamut Hr and Hg. The control device 50 performs an eighth display operation to display image C on the display device 14 based on the color values ​​converted by the color compression operation.

[0093] In this case, the control method for the printing device 10 is executed by the control device 50 according to the flowchart shown in Figure 27, which is an example of the control method. In the flowchart of Figure 27, the control device 50 executes steps S15 to S17 instead of step S9 in the flowchart of Figure 17.

[0094] Specifically, for example, when detailed display corresponding to a candidate color is input by the input device 15 (step S8: YES), the control device 50 determines whether or not there are image color values ​​d outside the print color gamut Hr and Hg within the image color gamut D (step S16). In this determination, if detailed display of a candidate color red is input, the control device 50 determines whether or not there are image color values ​​d among the multiple image color values ​​d in the image color gamut D acquired in the first acquisition operation in step S2 that are not included in the print color gamut Hr for red acquired in the second acquisition operation in step S3. In the example in Figure 9, all image color values ​​d in the image color gamut D are included in the print color gamut Hr. Therefore, the control device 50 determines that there are no image color values ​​d outside the print color gamut Hr within the image color gamut D (step S16: No), and executes the eighth display operation (step S17). In the eighth display operation, as shown in Figure 28(a), the control device 50 displays the image C on the display device 14 based on the image data without converting the image color values ​​d.

[0095] Furthermore, if detailed display of candidate green colors is input, the control device 50 determines whether there are any image color values ​​d in the image color gamut D acquired in the first acquisition operation of step S2 that are not included in the green print color gamut Hg acquired in the second acquisition operation of step S3 (step S16). In the example of Figure 10, color gamut d5 of the image color gamut D is not included in the print color gamut Hg, while the other color gamuts are included in the print color gamut Hg. In this case, the control device 50 determines that there are image color values ​​d outside the print color gamut Hg within the image color gamut D (step S16: Yes), and performs a color compression operation on these image color values ​​d (step S17). The control device 50 performs a color compression operation such as gamut mapping and converts the image color value d of color gamut d5 into a color value within the print color gamut Hg. For example, in the color compression operation, the control device 50 performs L * a * b * In the color space, the image color value d in color gamut d5 is converted to the color value in the print color gamut Hg that is closest in distance to that image color value d. The converted color value is the intersection point of the perpendicular line drawn from the image color value d on the contour of the print color gamut Hg.

[0096] Then, the control device 50 executes the eighth display operation. In the eighth display operation, as shown in Figure 28(b), the control device 50 displays image C on the display device 14 based on image data obtained by converting the image color value d of color gamut d5. As a result, in image C, the portion c5 corresponding to the color gamut d5 of the image color gamut D is displayed in a color different from the color based on the image data. On the other hand, the portion of image C other than portion c5 is displayed in a color based on the image data. In this way, the user can view image C when green is selected as a candidate color, select a spot color from the candidate colors, and improve the reproducibility of image C.

[0097] <Variation 10> The printing apparatus 10 according to Modification 10, as shown in Figure 29 in the above embodiment and Modifications 1 to 9, is equipped with a plurality of heads 60, as well as a transfer cylinder 70 and an impression cylinder 71 as a transport device. The printing apparatus 10 ejects ink from the heads 60 to the transfer cylinder 70, forms an image C on the transfer cylinder 70, and transfers the image C to the printing medium A.

[0098] The head 60 is a line head and has a plurality of nozzles 24. The plurality of nozzles 24 are arranged in a region that is longer than the printing area of ​​the printing medium A in the front-to-back direction. The nozzles 24 open to the lower surface of the head 60, and the lower surface faces the surface of the transfer cylinder 70. For example, the plurality of heads 60 eject different types of ink from each other. The plurality of heads 60 has, for example, four first heads 61 and three second heads 62. The first heads 61 are connected to the first tank 12a by a first flow path 13a and have first nozzles 24a that eject basic color ink. The second heads 62 are connected to the second tank 12b by a second flow path 13b and have second nozzles 24b that eject spot color ink different from the basic color. When a spot color ink selected from the candidate colors is stored in the second tank 12b, the spot color ink flows from the second tank 12b into the second flow path 13b, is filled, and is ejected from the second nozzles 24b.

[0099] The transfer cylinder 70 is cylindrical in shape with a central axis 70a extending in the front-to-back direction, and is rotatable around this central axis 70a. Multiple heads 60 are arranged radially from the central axis 70a of the transfer cylinder 70. The impression cylinder 71 is cylindrical in shape with a central axis 71a extending in the front-to-back direction, and is rotatable around this central axis 71a. The transfer cylinder 70 and the impression cylinder 71 are arranged vertically with the printing medium A sandwiched between them.

[0100] The transfer cylinder 70 is equipped with a transfer motor 70b, and the impression cylinder 71 is equipped with an impression cylinder motor 71b. The drive of these transfer motors 70b and impression cylinder motors 71b is controlled by a control device 50 (Figure 3). The transfer cylinder 70 and impression cylinder 71 rotate in opposite directions to transport the printing medium A in the forward and backward directions.

[0101] In the printing operation of this printing apparatus 10, the control device 50 rotates the transfer cylinder 70 and the impression cylinder 71 to transport the printing medium A forward, while simultaneously discharging basic color ink from the first nozzle 24a of the first head 21 and spot color ink from the second nozzle 24b of the second head 22 onto the transfer cylinder 70. This forms an image C on the transfer cylinder 70. This image C moves as the transfer cylinder 70 rotates and is pressed against the printing medium A between the transfer cylinder 70 and the impression cylinder 71, thereby being transferred. In this way, the image C is printed onto the printing medium A.

[0102] <Other variations> In the above embodiments and modifications 1 to 9, the printing system may include a plurality of heads 20, platens 11, a plurality of tanks 12, a transport device 30, a scanning device 40, a display device 14, an input device 15, and a control device 50. In this case, the plurality of heads 20, platens 11, a plurality of tanks 12, a transport device 30, and a scanning device 40 may constitute a printing unit, and the display device 14 and the input device 15 may be provided separately from this printing unit. In this case, the display device 14 and the input device 15 may be provided in a computer. Furthermore, the control device 50 may be provided in at least one of the printing unit and the computer.

[0103] In the embodiments and modifications, the third tank 12c is connected to the third head 23 by the third channel 13c, and the base color ink is supplied to the third head 23, but it is not limited to this. Instead of the base ink, a post-processing ink may be stored in the third tank 12c and supplied from the third tank 12c to the third head 23 by the third channel 13c. For example, the post-processing ink may be a transparent ink that imparts gloss.

[0104] In the embodiments and modifications, the base color ink was supplied to the first head 21 from the first tank 12a via the first channel 13a, the special color ink was supplied to the second head 22 from the second tank 12b via the second channel 13b, and the undercoat color ink was supplied to the third head 23 from the third tank 12c via the third channel 13c, but is not limited thereto. The base color ink, special color ink, and undercoat color ink may all be supplied to the same head 23. Specifically, the base color ink is supplied to the same head 23 from the first tank 12a via the first channel 13a, the special color ink from the second tank 12b via the second channel 13b, and the undercoat color ink from the third tank 12c via the third channel 13c. Furthermore, in this embodiment, the first head 21, the second head 22, and the third head 23 had different nozzle plates 27. However, if the basic color ink, special color ink, and base color ink are supplied to the same head 23, there may be only one nozzle plate 27. This nozzle plate 27 will have a first nozzle row 21a to 21d, a second nozzle row 22a to 22d, and a third nozzle row 23a to 23d. Moreover, if the basic color ink, special color ink, and base color ink are supplied to the same head 23, the number of nozzle rows in the second nozzle row 22a to 22d and the third nozzle row 23a to 23d may be reduced. For example, with respect to the second nozzle rows 22a to 22d and the third nozzle rows 23a to 23d, the second nozzle rows 22b to 22d and the third nozzle rows 23b to 23d may be reduced to just the second nozzle row 22a and the third nozzle row 23a.

[0105] In the embodiment and modified examples, the base color ink was supplied from the first tank 12a to the first head 21 via the first channel 13a, the special color ink was supplied from the second tank 12b to the second head 22 via the second channel 13b, and the undercoat color ink was supplied from the third tank 12c to the third head 23 via the third channel 13c. The first channel 13a, the second channel 13b, and the third channel 13c were rubber tubes and plastic tubes, respectively, and constituted a so-called off-carriage configuration, but are not limited to this. An on-carriage configuration is also possible. In an on-carriage configuration, the carriage 41 comprises the first head 21, the second head 22, the third head 23, the first tank 12a, the second tank 12b, and the third tank 12c, and does not have channels made of rubber tubes or plastic tubes. In the on-carriage configuration, the first channel 13a, the second channel 13b, and the third channel 13c are made of resin, rather than rubber or plastic tubing. For example, if the head 20 is formed from a laminate of multiple resin plates stacked together, the channels 13a, 13b, and 13c may be formed from through holes and depressions provided in the laminate.

[0106] In the embodiments and modifications, the carriage 41 had a first head 21, a second head 22, and a third head 23, but is not limited thereto. The carriage 41 may have the first head 21 and the second head 22 without the third head 23.

[0107] In the embodiment, the carriage 41 had two first heads 21, two second heads 22, and two third heads 23, but is not limited to this. The carriage 41 may have one first head 21, one second head 22, and one third head 23. Alternatively, the carriage 41 may have three or more first heads 21, three or more second heads 22, and three or more third heads 23.

[0108] In the printing apparatus 10 according to modification 9, the patch p is a color swatch representing the image color value d and has a rectangular shape, but is not limited to this. The patch p may have a polygonal shape other than a rectangle, or it may be circular.

[0109] In the printing apparatus 10 according to Modification 9, the determination result was that for image color values ​​d not included in the print color gamut Hr, a mark q such as "×" was used on the patch p, but this is not limited to this. For image color values ​​d included in the print color gamut Hr, a mark q such as "〇" may be used on the patch p.

[0110] In the modified example 10, the printing system may also include a plurality of heads 60, platens 11, a plurality of tanks 12, a transfer cylinder 70, an impression cylinder 71, a display device 14, an input device 15, and a control device 50. In this case as well, the plurality of heads 60, platens 11, a plurality of tanks 12, a transfer cylinder 70, and an impression cylinder 71 may constitute a printing unit, and the display device 14 and the input device 15 may be provided separately from this printing unit. In this case, the display device 14 and the input device 15 may be provided in a computer. The control device 50 may also be provided in at least one of the printing unit and the computer.

[0111] Furthermore, all of the above embodiments may be combined with each other, provided that they do not exclude one another. Also, 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 interpreted as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of its structure and / or function can be substantially modified without departing from the spirit of the invention. [Industrial applicability]

[0112] This invention can be applied to a printing apparatus, a control method thereof, and a computer program that can improve the color calibration of images. [Explanation of Symbols]

[0113] 10:Printing device 13a: First channel 13b: Second channel 14:Display device 15: Input device 24a: First nozzle 24b: Second nozzle 50: Control device

Claims

1. A first nozzle prints an image onto a printing medium based on image data using a predetermined basic color ink, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, Display device and A control device is provided, The control device is A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Execute, The image color gamut includes a first color gamut which is the region in the color space occupied by the color values ​​included in the image data of the first portion of the image that has a size of a predetermined size or larger and color values ​​that are greater than or equal to a predetermined color difference from the surrounding color values. The control device is Further, a determination operation is performed to determine whether or not the first color gamut is included in the print color gamut. If the first color gamut is included in the print color gamut, in the first display operation, the result of the determination operation is displayed on the display device in addition to the ranking of the candidate colors. Printing device.

2. The aforementioned image color gamut includes the color values ​​of the image data of the multiple aforementioned images. The printing apparatus according to claim 1.

3. The aforementioned evaluation value includes the ratio of the area of ​​the portion of the image corresponding to the image color gamut included in the print color gamut to the total area of ​​the image. The printing apparatus according to claim 1 or 2.

4. The aforementioned evaluation value includes the ratio of the volume of the image color gamut included in the print color gamut to the volume of the image color gamut in the color space, The printing apparatus according to claim 1 or 2.

5. The control device performs a second display operation to display the image on the display device in such a way that it distinguishes between a portion of the image corresponding to a color value in an area of ​​the image color gamut that is not included in the print color gamut and a portion of the image corresponding to a color value in an area of ​​the image color gamut that is included in the print color gamut. The printing apparatus according to any one of claims 1 to 4.

6. The control device performs a conversion process to convert the color values ​​of the region of the image color gamut that is not included in the print color gamut into other color values. The display device displays the portion of the image corresponding to the color values ​​of the region of the image color gamut that is not included in the print color gamut, based on the other color values. The display device displays the portion of the image corresponding to the color values ​​of the region included in the print color gamut within the image color gamut without performing the conversion process. The printing apparatus according to claim 5.

7. A first nozzle that prints an image onto a printing medium based on image data using ink of a predetermined basic color, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, Display device and A control device is provided, The control device is A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Execute, The display device further comprises an input device capable of specifying the position, The control device is A third display operation, which displays the color space representing the image color gamut on the display device, A fourth display operation is performed, which involves displaying on the display device the color difference between the color value of the image corresponding to the position in the color space specified by the input device and the print color gamut. Printing device.

8. A first nozzle that prints an image onto a printing medium based on image data using ink of a predetermined basic color, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, Display device and A control device is provided, The control device is A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Execute, The control device further performs a fifth display operation, which displays a label at the contour position of the print color gamut, expressing that the color difference with the image color gamut increases as one moves away from the contour position outside the print color gamut by changing at least one of hue, lightness, and saturation. Printing device.

9. The control device performs a sixth display operation, which involves replacing the colors of each pixel in the image that are outside the print color gamut with colors whose hue, brightness, and saturation are changed according to the color difference with the print color gamut, and then displaying the image on the display device. A printing apparatus according to any one of claims 1 to 8.

10. In the sixth display operation, the control device replaces the colors of each pixel in the image that are within the print color gamut with a single color different from the color that replaces the color outside the print color gamut, and displays the image on the display device. The printing apparatus according to claim 9.

11. A first nozzle that prints an image onto a printing medium based on image data using ink of a predetermined basic color, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, Display device and A control device is provided, The control device is A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Execute, The control device further performs a seventh display operation, which involves displaying a patch chart on the display device in which the patches corresponding to each color value in the image are arranged on a plane, in order to distinguish the patches corresponding to color values ​​not included in the printable color gamut from the patches corresponding to color values ​​included in the printable color gamut. Printing device.

12. A first nozzle that prints an image onto a printing medium based on image data using ink of a predetermined basic color, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, Display device and A control device is provided, The control device is A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Execute, The control device is A color compression operation that converts the color values ​​of the aforementioned image into the color values ​​of the print color gamut, An eighth display operation is performed, which involves displaying the image on the display device based on the color values ​​converted by the color compression operation. Printing device.

13. A first nozzle prints an image onto a printing medium based on image data using a predetermined basic color ink, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, A method for controlling a printing apparatus equipped with a display device, A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Make it run, The image color gamut includes a first color gamut which is the region in the color space occupied by the color values ​​included in the image data of the first portion of the image that has a size of a predetermined size or larger and color values ​​that are greater than or equal to a predetermined color difference from the surrounding color values. moreover, A determination operation is performed to determine whether or not the first color gamut is included in the print color gamut. If the first color gamut is included in the print color gamut, the first display operation will display the result of the determination operation in addition to the ranking of the candidate colors on the display device. A method for controlling a printing device.

14. A first nozzle prints an image onto a printing medium based on image data using a predetermined basic color ink, A second nozzle prints an image onto a printing medium based on the image data using a special ink different from the aforementioned basic color, A first channel for supplying the aforementioned basic color ink to the first nozzle, A second channel for supplying the aforementioned special ink to the second nozzle, A printing apparatus equipped with a display device, A first acquisition operation to acquire an image color gamut, which is the region in a predetermined color space occupied by the color values ​​contained in the image data, A second acquisition operation is performed to acquire a printable color gamut for a plurality of candidate colors that can be selected as the aforementioned feature colors, wherein the color values ​​of the printable colors of the first nozzle and the second nozzle, using the inks of the candidate colors and the inks of the basic colors, occupy the area of ​​the color space. A third acquisition operation to obtain evaluation values ​​when comparing the print color gamut and the image color gamut for multiple candidate colors, Before the second channel is filled with the special-color ink, a first display operation is performed to display the ranking of the candidate colors based on the evaluation value on the display device, Make it run, The image color gamut includes a first color gamut which is the region in the color space occupied by the color values ​​included in the image data of the first portion of the image that has a size of a predetermined size or larger and color values ​​that are greater than or equal to a predetermined color difference from the surrounding color values. moreover, A determination operation is performed to determine whether or not the first color gamut is included in the print color gamut. If the first color gamut is included in the print color gamut, the first display operation will display the result of the determination operation in addition to the ranking of the candidate colors on the display device. Computer program.

Images