Color conversion method, printing method, and image processing device

Abstract

This color conversion method for forming a print product including a protrusion region 201, which has a three-dimensional shape, and a non-protrusion region 202 recessed relative to the protrusion region 201 includes: a data acquisition step S10 for acquiring image data D0 of an image to be printed; a data separation step S20 for acquiring image data D0a corresponding to the protrusion region 201 and image data D0b corresponding to the non-protrusion region 202 from the image data D0; a first color conversion step S30A for performing first color conversion C1 on the image data D0a corresponding to the protrusion region 201 to obtain print data D2a of an image corresponding to the protrusion region 201; and a second color conversion step S30B for performing second color conversion C2 different from the first color conversion C1 on the image data D0b corresponding to the non-protrusion region 202 to obtain print data D2b of an image corresponding to the non-protrusion region 202.

Description

Color conversion method, printing method, and image processing apparatus

[0001] The present invention relates to a color conversion method, a printing method, and an image processing apparatus for generating print data from image data of a printed image.

[0002] A method of forming a printed product including a convex region having a three-dimensional shape and a non-convex region recessed more than the convex region has been conventionally known. For example, Patent Document 1 discloses a method of forming a printed product including a convex region and a non-convex region using a foaming medium provided with a foaming layer that generates gas upon heating. In the method described in Patent Document 1, a foaming suppression ink that penetrates into the foaming layer and chemically suppresses foaming and a coloring ink are used. In the method described in Patent Document 1, in the emboss data, for the region outside the region that becomes a convex part, ejection of the foaming suppression ink is specified, and for the region inside the region that becomes a convex part, non-ejection of the foaming suppression ink is specified, thereby forming the convex part and the region other than the convex part on the foaming medium. The image is formed by the coloring ink.

[0003] According to Patent Document 1, there may be a problem that the ink layer printed on the foaming region cracks due to the expansion of the foaming medium, the background color of the foaming medium is visible, and the density of the image printed on the foaming region appears thinner than the image printed on the non-foaming region. In the method described in Patent Document 1, in order to eliminate this density difference, the ejection amount of the coloring ink when printing on the foaming region is made larger than the ejection amount of the coloring ink when printing on the non-foaming region.

[0004] Japanese Patent Application Laid-Open No. 2020-138498

[0005] In addition to the printed product in which a part of the foaming medium as described in Patent Document 1 is foamed, there is a printed product including a convex region and a non-convex region and printed on the convex region and the non-convex region (for example, a printed product in which an ink layer is laminated to form a convex region). And according to the findings of the inventor of the present application, in such a printed product, a color difference between the convex region and the non-convex region may occur, not only the density difference as described in Patent Document 1.

[0006] The present invention has been made in view of the above, and its objective is to provide a method for reducing the color difference between raised and non-raised regions when forming a printed product that includes raised and non-raised regions. Furthermore, it aims to provide an apparatus for realizing such a method.

[0007] A method disclosed herein is a color conversion method for forming a printed product that includes a convex region having a three-dimensional shape and a non-convex region that is recessed compared to the convex region, and includes: a data acquisition step of acquiring image data of an image to be printed; a data separation step of acquiring from the image data image data corresponding to the convex region and image data corresponding to the non-convex region, respectively; a first color conversion step of performing a first color conversion on the image data corresponding to the convex region to obtain print data of the image corresponding to the convex region; and a second color conversion step of performing a second color conversion different from the first color conversion on the image data corresponding to the non-convex region to obtain print data of the image corresponding to the non-convex region.

[0008] Furthermore, the image processing apparatus disclosed herein includes: a data acquisition unit that acquires image data of an image to be printed; a data separation unit that, when creating print data including a convex region having a three-dimensional shape and a non-convex region recessed more than the convex region from the image data acquired by the data acquisition unit, acquires image data corresponding to the convex region and image data corresponding to the non-convex region from the image data; a first color conversion unit that performs a first color conversion on the image data corresponding to the convex region to create print data of the image corresponding to the convex region; and a second color conversion unit that performs a second color conversion different from the first color conversion on the image data corresponding to the non-convex region to create print data of the image corresponding to the non-convex region.

[0009] According to the above color conversion method and image processing apparatus, by performing a first color conversion on image data corresponding to a convex region and a second color conversion different from the first color conversion on image data corresponding to a non-convex region, it is possible to print with different color tones for the convex and non-convex regions. This printing with different color tones cancels out the color difference caused by the difference between the convex and non-convex regions, and the color difference between the convex and non-convex regions in the printed output can be reduced.

[0010] This is a block diagram showing an example configuration of a printing system according to one embodiment. This is a schematic cross-sectional view of a printer. This is a schematic cross-sectional view of a printed product. This is a flowchart showing an example of the process for creating a first output ICC profile and a second output ICC profile. This is a schematic plan view showing a color chart without foam-suppressing ink ejection and a color chart with foam-suppressing ink ejection. This is a flowchart showing an example of the color conversion and printing process according to the first embodiment. This is a flowchart showing an example of the color conversion process according to the second embodiment. This is a flowchart showing an example of the color conversion process according to the third embodiment. This is a schematic cross-sectional view of a printed product including a plurality of protrusions.

[0011] The printing system according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the embodiments described herein are not intended to particularly limit the present invention. Furthermore, the same reference numerals are used for components and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate.

[0012] [First Embodiment] Figure 1 is a block diagram showing an example configuration of a printing system 1 according to one embodiment. As shown in Figure 1, the printing system 1 includes an image processing device 100 and an inkjet printer 10 (hereinafter simply referred to as the printer 10). Figure 2 is a schematic cross-sectional view of the printer 10. The symbols F, Rr, L, R, U, and D in the drawing indicate the front, back, left, right, top, and bottom of the printer 10, respectively. The image processing device 100 is, in this case, a computer on which software for creating print data to be transmitted to the printer 10 from image data of an image to be printed is installed. However, the image processing device 100 may be a dedicated device equipped with hardware and software for creating print data. The printer 10 is communicatively connected to the image processing device 100. The image processing device 100 is configured to transmit print data to the printer 10. The printer 10 performs printing based on the print data transmitted from the image processing device 100 and forms an image on the recording medium 5 (see Figure 2). Some or all of the functions of the image processing device 100 may be realized by a control device 70 of the printer 10, which will be described later.

[0013] In this embodiment, the recording medium 5 is a heat-expandable medium that expands when heated. Here, the recording medium 5 is a foaming recording medium that expands when the heated portion foams. The recording medium 5 has a base portion made of, for example, a film, and a heat-expandable layer. The heat-expandable layer is formed, for example, by heat-expandable microcapsules coated on the base portion. The heat-expandable layer contains a foaming agent and additives. The foaming agent may be, for example, 0.1 to 10 parts by weight per 100 parts by weight of a polyolefin material with an elastic modulus of less than 0.1 GPa. The foaming agent is selected from azodicarbonamide and / or their metal salts, hydrazodicarbonamide, sodium bicarbonate, trihydrazino-sym-triazine, pp'-oxybisbenzenesulfonyl hydrazide, dinitrosopentamethylenetetramine, azobisisobutyl-oddinitrile, p-toluenesulfonyl hydrazide, bisbenzenesulfonyl hydrazide, etc. The polyolefin material described above is selected from thermoplastic elastomer polyolefins, ethylene-vinyl acetate copolymers, atactic polypropylene polymers, or mixtures thereof. The thickness of the heat-foamed layer is preferably, for example, 0.05 mm to 0.3 mm. The amount of additive is preferably, for example, 0 to 200 parts by weight.

[0014] [Printer Configuration] The printer 10 is an inkjet printer. As shown in Figure 2, in this embodiment, the printer 10 prints an image on the recording medium 5 by sequentially moving the rolled recording medium 5 forward while unwinding it, and by ejecting color ink I1 from the color ink head 21 of the recording head 20. The printer 10 also ejects foam-suppressing ink I2 from the foam-suppressing ink head 22 of the recording head 20 to suppress foaming and bulging of the recording medium 5 due to heating. The foam-suppressing ink I2 is, for example, an aqueous ink suitable for the polyolefin surface that forms the heated foam layer of the recording medium 5. In this case, the foam-suppressing ink I2 is a transparent ink. However, the foam-suppressing ink I2 may be a colored ink. The printer 10 heats the recording medium 5 after the color ink I1 and foam-suppressing ink I2 have been ejected. The foam-suppressing ink I2 is ejected to the areas of the recording medium 5 that are not to be bulged. In the parts of the recording medium 5 where the foam-suppressing ink I2 was not ejected, the heating of the recording medium 5 forms a convex region 201 (see Figure 3) having a three-dimensional shape. In the recording medium 5, the portion where the foam-suppressing ink I2 is ejected forms a non-convex region 202 (see Figure 3) that is recessed compared to the convex region 201.

[0015] As shown in Figure 2, the printer 10 includes a recording head 20, a supply roll 30, a take-up roll 35, a transport device 40, a head moving device 50, a heating device 60, and a control device 70 (see Figure 1). The supply roll 30 rotatably supports the recording medium 5 wound in a roll shape. The transport device 40 transports the recording medium 5 unwound from the supply roll 30 forward. The transport device 40 transports the recording medium 5 by sandwiching it between a grid roller 41 embedded in the platen 15 and a pinch roller 42 positioned opposite the grid roller 41, and by rotating the grid roller 41 with a transport motor 43. Above the platen 15 is a carriage 25 on which the recording head 20 is mounted. The head moving device 50 moves the carriage 25 in the left-right direction. The head moving device 50 includes a guide rail 51 extending in the left-right direction. The carriage 25 is engaged with the guide rail 51 so as to be slidable in the left-right direction. The head moving device 50 includes a scan motor (not shown) that moves the carriage 25 along the guide rail 51.

[0016] In this embodiment, the recording head 20 includes a color ink head 21 that ejects color ink I1 and a foam suppression ink head 22 that ejects foam suppression ink I2. The color ink head 21 ejects, for example, CMYK (cyan, magenta, yellow, black) color ink I1. However, the type of color ink I1 ejected from the color ink head 21 is not particularly limited. The color ink I1 may include, for example, special color inks such as white or metallic. The color ink head 21 and the foam suppression ink head 22 are arranged side by side in the left-right direction. The color ink head 21 and the foam suppression ink head 22 are arranged in a so-called staggered configuration, with their positions offset in the front-back direction. The foam suppression ink head 22 is positioned behind the color ink head 21. However, the color ink head 21 and the foam suppression ink head 22 may be aligned in the front-back direction, and the foam suppression ink head 22 may be positioned in front of the color ink head 21. The recording head 20 only needs to be configured to eject color ink I1 and foam-suppressing ink I2, and the number of ink heads that the recording head 20 has is not limited.

[0017] The heating device 60 is located in front of the platen 15. The heating device 60 heats the recording medium 5 on which the color ink I1 and foam-suppressing ink I2 have been ejected on the platen 15. The heating device 60 comprises a box-shaped heating device body 61 and a plurality of ceramic heaters 62 (only one is shown in Figure 2). The heating device body 61 is provided with an inlet and outlet for the conveyed recording medium 5. The plurality of ceramic heaters 62 are located inside the heating device body 61, facing the conveying path of the recording medium 5. Although only one is shown in Figure 2, the plurality of ceramic heaters 62 are arranged side by side in the left-right direction.

[0018] The winding roll 35 winds up the printed product 6. The printed product 6 is, in this case, a recording medium 5 that has been heated after the color ink I1 and foam-suppressing ink I2 have been ejected, and has a convex region 201 and a non-convex region 202 (see Figure 3).

[0019] The control device 70 is connected to the recording head 20, the head moving device 50, the transport device 40, the heating device 60, and the winding roll 35, and controls their operation. The configuration of the control device 70 is not particularly limited. The control device 70 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but for example, it includes an interface (I / F) for receiving print data from external devices such as an image processing device 100, a central processing unit (CPU) for executing instructions of the control program, a read-only memory (ROM) for storing programs executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as memory for storing programs and various data. Some of the functions of the control device 70 of the printer 10 may be realized by a computer on which the image processing device 100 is configured.

[0020] As shown in Figure 1, the control device 70 includes a data receiving unit 71 that receives print data transmitted from the image processing device 100, and a print control unit 72 that controls the recording head 20, head moving device 50, transport device 40, heating device 60, etc., to perform printing.

[0021] The printer 10 ejects foam-suppressing ink I2 onto a portion of the recording medium 5 that foams when heated. The printer 10 forms a convex region 201 due to the foaming caused by heating of the recording medium 5, and forms a non-convex region 202 in the area of ​​the recording medium 5 where the foam-suppressing ink I2 was ejected. Here, the printer 10 intermittently moves the recording medium 5 forward while ejecting foam-suppressing ink I2 from the foam-suppressing ink head 22 toward the recording medium 5. The printer 10 also ejects color ink I1 toward the recording medium 5 from a color ink head 21 located in front of the foam-suppressing ink head 22 (downstream in the transport direction of the recording medium 5). As a result, the foam-suppressing ink I2 permeates the heated foaming layer of the recording medium 5, and a color ink layer Lc (see Figure 3) is formed on the recording medium 5. The recording medium 5 is then transported to the heating device 60 and heated by the heating device 60. As a result, the portion where the foam-suppressing ink I2 was not ejected foams and expands, forming a convex region 201. Furthermore, if the foam-suppressing ink head 22 is positioned in front of the color ink head 21, the color ink I1 is ejected from the color ink head 21 towards the recording medium 5, and then the foam-suppressing ink I2 is ejected from the foam-suppressing ink head 22 towards the recording medium 5.

[0022] Figure 3 is a schematic cross-sectional view of the printed product 6. As shown in Figure 3, the printed product 6 comprises a convex region 201 having a three-dimensional shape as a result of foaming and expansion, and a non-convex region 202 that is recessed compared to the convex region 201 as a result of suppressed foaming and expansion. A color ink layer Lc is formed on both the convex region 201 and the non-convex region 202.

[0023] [Image Processing Device] The image processing device 100 creates print data D2 to be sent to the printer 10 from image data D0 of the image to be printed. Image data D0 is, for example, CMYK ink value data. However, image data D0 may also be, for example, RGB data for monitor display. Print data D2 is, in this case, CMYK ink value data. Because the color tones realized by printing devices such as printers differ depending on the model, the image processing device 100 uses an ICC (International Color Consortium) profile input profile (input ICC profile) to convert device-dependent (for example, CMYK ink value) image data D0 into device-independent color space color value data (for example, L ＊ a ＊ b ＊ The image processing device 100 converts the device-independent color value data obtained in this way into device-dependent print data D2 (here, CMYK ink values) using the output ICC profile. When converting device-dependent image data into color values ​​in a device-independent color space, a conversion table called the A2B table in the ICC profile is used. Conversely, when converting color values ​​in a device-independent color space into device-dependent print data, a conversion table called the B2A table in the ICC profile is used.

[0024] Furthermore, the image processing device 100 specifies the region where foam-suppressing ink I2 is ejected, that is, the region in the printed output 6 that becomes a non-convex region 202. However, the region where foam-suppressing ink I2 is ejected may already be specified in the image data D0 transmitted to the image processing device 100. Color ink I1 and foam-suppressing ink I2 are ejected into the non-convex region 202. Only color ink I1 is ejected into the convex region 201. Note that it is not prohibited for a small amount of foam-suppressing ink I2 to be ejected into the convex region 201, but for convenience, below, the expression "no foam-suppressing ink I2 is ejected" will be used to include the ejection of a small amount of foam-suppressing ink I2 that is clearly distinguishable from the amount ejected into the non-convex region 202.

[0025] In this embodiment, when the image processing apparatus 100 creates print data D2 including a convex region 201 and a non-convex region 202 from image data D0 acquired by the data acquisition unit 110, it performs different color conversion processing on image data D0a corresponding to the convex region 201 and image data D0b corresponding to the non-convex region 202.

[0026] In this embodiment, color ink I1 and foam-suppressing ink I2 are ejected into the non-convex region 202, while only color ink I1 is ejected into the convex region 201. As a result, a difference in color due to the presence or absence of foam-suppressing ink I2 occurs between the convex region 201 and the non-convex region 202. When the image data D0 in this embodiment includes both the convex region 201 and the non-convex region 202, the image processing apparatus 100 performs different color conversion processing on the image data D0a corresponding to the convex region 201 and the image data D0b corresponding to the non-convex region 202 in order to reduce such a difference in color. Hereinafter, the color conversion processing for the image data D0a corresponding to the convex region 201 (color conversion processing without considering foam-suppressing ink I2) will also be referred to as the first color conversion processing C1 (see Figure 6), and the color conversion processing for the image data D0b corresponding to the non-convex region 202 (color conversion processing considering foam-suppressing ink I2) will also be referred to as the second color conversion processing C2 (see also Figure 6).

[0027] The second color conversion process C2 is set so that a predetermined color in the input image data (for example, a predetermined green) appearing in the non-convex region 202 approaches (ideally, becomes the same as) the same predetermined color appearing in the convex region 201 (based on the print data obtained by the first color conversion process C1). Therefore, the difference between the color obtained when printing on the convex region 201 using the print data obtained by performing the first color conversion process C1 on the predetermined color, and the color obtained when printing on the non-convex region 202 using the print data obtained by performing the second color conversion process C2 on the predetermined color, is smaller than the difference between the colors of the convex region 201 and the non-convex region 202 when printing on the convex region 201 and the non-convex region 202 using print data obtained by performing a common color conversion on the predetermined color. As a result, when the print data obtained by performing the second color conversion process C2 on a predetermined color is executed and printed on the non-convex region 202, the color (i.e., the color that appears in the non-convex region 202) is closer to the color (i.e., the color that appears in the convex region 201) when the print data obtained by performing the first color conversion process C1 on the predetermined color is executed and printed on the non-convex region 202, than to the color (in other words, the color when the same color conversion process as for the convex region 201 is performed) when the print data obtained by performing the first color conversion process C1 on the predetermined color is executed and printed on the convex region 201. The method for determining the first color conversion process C1 and the second color conversion process C2 will be described later.

[0028] As shown in Figure 1, the image processing apparatus 100 includes a data acquisition unit 110 that acquires image data D0 of an image to be printed, a data separation unit 120 that separates the image data D0 acquired by the data acquisition unit 110 into image data D0a corresponding to a convex region 201 and image data D0b corresponding to a non-convex region 202, a conversion processing unit 130 that converts the acquired image data D0 into print data D2 (performing a first color conversion process C1 and a second color conversion process C2), and a data transmission unit 140 that transmits the print data D2 to the printer 10.

[0029] As shown in Figure 1, when the data separation unit 120 creates print data D2a and D2b including a convex region 201 and a non-convex region 202 from image data D0 acquired by the data acquisition unit 110, it acquires image data D0a corresponding to the convex region 201 and image data D0b corresponding to the non-convex region 202 from image data D0. The image data D0a corresponding to the convex region 201 and the image data D0b corresponding to the non-convex region 202 can be distinguished by whether or not they are specified to eject foam-suppressing ink I2. The acquisition of image data D0a of the convex region 201 and image data D0b of the non-convex region 202 may substantially be the designation of the non-convex region 202 by the image processing device 100 (designation of the region to eject foam-suppressing ink I2).

[0030] As shown in Figure 1, the conversion processing unit 130 includes a first color conversion unit 131 and a second color conversion unit 132. The first color conversion unit 131 performs a first color conversion process C1 on image data D0a corresponding to the convex region 201 to create print data D2a of the image corresponding to the convex region 201. The second color conversion unit 132 performs a second color conversion process C2, which is different from the first color conversion process C1, on image data D0b corresponding to the non-convex region 202 to create print data D2b of the image corresponding to the non-convex region 202.

[0031] In this embodiment, the first color conversion unit 131 and the second color conversion unit 132 convert image data D0a and D0b into color value data D1a and D1b (both see Figure 6) respectively using a common input ICC profile (A2B table) Pi (see Figure 6). Then, the first color conversion unit 131 converts the color value data D1a corresponding to the convex region 201 using a first output ICC profile (first B2A table) Po1 (see Figure 6) to create print data D2a of the image corresponding to the convex region 201. The second color conversion unit 132 converts the color value data D1b corresponding to the non-convex region 202 using a second output ICC profile (second B2A table) Po2 (see Figure 6) which is different from the first output ICC profile Po1 to create print data D2b of the image corresponding to the non-convex region 202. In this embodiment, the first color conversion process C1 and the second color conversion process C2 differ due to the different output ICC profiles (B2A table). The first color conversion unit 131 performs halftone processing and pass decomposition processing on the color-converted print data to create print data D2a corresponding to the convex region 201. Halftone processing is the process of converting print data represented by ink values ​​into ink dot data. Pass decomposition processing is the process of converting the dot data created by the halftone processing into data for each pass. The second color conversion unit 132 performs halftone processing and pass decomposition processing on the color-converted print data to create print data D2b corresponding to the non-convex region 202.

[0032] [Creating Output ICC Profiles] The following describes how to create the first output ICC profile Po1 and the second output ICC profile Po2. Figure 4 is a flowchart showing an example of the process for creating the first output ICC profile Po1 and the second output ICC profile Po2. As shown in Figure 4, in step S01 of the process for creating output ICC profiles Po1 and Po2, the same color charts 300A and 300B are printed by the printer 10, except for the presence or absence of foam-suppressing ink ejection. Note that this printing includes foam expansion due to heating of the recording medium 5. Figure 5 is a schematic plan view showing color chart 300A without foam-suppressing ink I2 ejection and color chart 300B with foam-suppressing ink I2 ejection. As shown in Figure 5, color chart 300A includes multiple color patches 301A of different colors. The multiple color patches 301A are printed based on the print data of the original image without color conversion by the input ICC profile and output ICC profile. However, multiple color patches 301A may be printed based on print data obtained by color-converting the original image using one input ICC profile and one output ICC profile. Foam-suppressing ink I2 is not ejected from the multiple color patches 301A.

[0033] As shown in Figure 5, the color chart 300B also includes multiple color patches 301B of different colors. The multiple color patches 301B are printed based on the same source image print data as the color chart 300A. Foam-suppressing ink I2 is ejected from the multiple color patches 301B.

[0034] As shown in Figure 4, in step S02, the colors of multiple color patches 301A and 301B are measured using a colorimeter. This yields the color values ​​of multiple color patches 301A and 301B.

[0035] In step S03, an output ICC profile (first output ICC profile) Po1 is created that represents the relationship between the color values ​​of the multiple color patches 301A measured in step S02 and the ink values ​​of the original images of the multiple color patches 301A. That is, a relationship table is created between device-independent color values ​​and device-dependent ink values ​​when the foam-suppressing ink I2 is not ejected.

[0036] In step S04, an output ICC profile (second output ICC profile) Po2 is created that represents the relationship between the color values ​​of the multiple color patches 301B measured in step S02 and the ink values ​​of the original images of the multiple color patches 301B. That is, a relationship table is created between device-independent color values ​​and device-dependent ink values ​​when the foam-suppressing ink I2 is ejected. However, the method for creating the first output ICC profile Po1 and the second output ICC profile Po2 is not limited to this. For example, the first output ICC profile Po1 and the second output ICC profile Po2 may be adjusted so that the convex region 201 and the non-convex region 202 have similar color tones.

[0037] [Color Conversion and Printing Process] The color conversion and printing process is described below. Figure 6 is a flowchart of an example of the color conversion and printing process. As shown in Figure 6, in the data acquisition step S10 of the color conversion and printing process, image data D0 of the image to be printed is acquired. In the data separation step S20, image data D0a corresponding to the convex region 201 and image data D0b corresponding to the non-convex region 202 are acquired from the image data D0. In the first color conversion step S30A, the first color conversion process C1 is performed on the image data D0a corresponding to the convex region 201 to obtain print data D2a of the image corresponding to the convex region 201. In the second color conversion step S30B, a second color conversion process C2 different from the first color conversion process C1 is performed on the image data D0b corresponding to the non-convex region 202 to obtain print data D2b of the image corresponding to the non-convex region 202.

[0038] More specifically, in step S31A of the first color conversion process C1, the image data D0a corresponding to the convex region 201 is converted using the input ICC profile Pi, which is common to both the first color conversion process C1 and the second color conversion process C2, to obtain color value data D1a corresponding to the convex region 201. In step S32A of the first color conversion process C1, the color value data D1a corresponding to the convex region 201 is converted using the first output ICC profile Po1 to obtain print data D2a of the image corresponding to the convex region 201.

[0039] In step S31B of the second color conversion process C2, the image data D0b corresponding to the non-convex region 202 is converted using the same input ICC profile Pi as the first color conversion process C1 to obtain color value data D1b corresponding to the non-convex region 202. In step S32B of the second color conversion process C2, the color value data D1b corresponding to the non-convex region 202 is converted using the second output ICC profile Po2, which is different from the first output ICC profile Po1, to obtain print data D2b of the image corresponding to the non-convex region 202.

[0040] In the process illustrated here, step S31A, which obtains the color value data D1a of the convex region 201, and step S31B, which obtains the color value data D1b of the non-convex region 202, are performed simultaneously and in combination. In this embodiment, in steps S31A and S31B, the entire image data D0 is color-converted using the input ICC profile Pi and converted into color values. The order in which each part of the image data D0 is converted into color values ​​may be in an order that is easy to process, for example, in the order in which the data is written. In that case, parts of step S31A and parts of step S31B may be performed alternately. However, steps S31A and S31B may be performed separately. In steps S31A and S31B, the same color value is obtained from the same color in the image data D0, regardless of whether it is the color of the convex region 201 or the color of the non-convex region 202. Note that the input ICC profile Pi used in steps S31A and S31B may be arbitrarily selected by the user.

[0041] Step S32A, which obtains print data D2a for the convex region 201, and Step S32B, which obtains print data D2b for the non-convex region 202, are performed separately. Steps S32A and S32B may be performed simultaneously or sequentially. Because the output ICC profiles used in Step S32A and Step S32B are different, different CMYK ink values ​​can be obtained depending on whether it is the color of the convex region 201 or the color of the non-convex region 202, even from the same color (having the same CMYK ink value) in the image data D0. The print data (CMYK ink values) of the convex region 201 and non-convex region 202 obtained by color conversion are subjected to halftone processing and pass decomposition processing and converted into printable print data D2a and D2b (dot data for each pass) that can be printed by the printer 10.

[0042] In the transmission step S40, the print data D2a for the convex region 201 and the print data D2b for the non-convex region 202 are sent to the printer 10. In the printing step S50, printing is performed on the recording medium 5 based on the print data D2a for the convex region 201 and the print data D2b for the non-convex region 202. As shown in Figure 6, the printing step S50 includes the steps of: step S51, which ejects color ink I1 to the portion of the recording medium 5 corresponding to the convex region 201 based on the print data D2a of the image corresponding to the convex region 201 obtained in the first color conversion step S30A; step S52, which ejects foam suppression ink I2 and color ink I1 to the portion of the recording medium 5 corresponding to the non-convex region 202 based on the print data D2b of the image corresponding to the non-convex region 202 obtained in the second color conversion step S30B; and step S53, which heats the recording medium 5.

[0043] In this embodiment, steps S51 and S52 are performed simultaneously. That is, in steps S51 and S52, the anti-foaming ink I2 is ejected to a portion corresponding to the non-convex region 202 of the recording medium 5 by the anti-foaming ink head 22, and then, the color ink I1 is intermittently ejected to portions corresponding to the convex region 201 and the non-convex region 202 of the recording medium 5 by the color ink head 21 disposed in front of the anti-foaming ink head 22. When the anti-foaming ink head 22 is disposed in front of the color ink head 21, the color ink I1 may be intermittently ejected toward portions corresponding to the convex region 201 and the non-convex region 202 of the recording medium 5 by the color ink head 21, and then, the anti-foaming ink I2 may be intermittently ejected to a portion corresponding to the non-convex region 202 of the recording medium 5 by the anti-foaming ink head 22.

[0044] In this embodiment, the first output ICC profile Po1 and the second output ICC profile Po2 are both tables of the relationship between device-independent color values and device-dependent ink values, except for the presence or absence of the anti-foaming ink I2. Since the relationship tables associated with the common device-independent color values are used in the first color conversion process C1 and the second color conversion process C2, respectively, the hues of the convex region 201 and the non-convex region 202 can be made closer. In this embodiment, the first output ICC profile Po1 and the second output ICC profile Po2 are designed so as to make the hues of the convex region 201 and the non-convex region 202 closer in this way. Therefore, the hue difference between the convex region 201 and the non-convex region 202 can be made smaller than in the conventional method of performing the same color conversion on the image data D0a of the convex region 201 and the image data D0b of the non-convex region 202.

[0045] [Operational Effects of the First Embodiment] Hereinafter, the operational effects that can be achieved by the color conversion method according to this embodiment will be described.

[0046] The color conversion method according to this embodiment is a color conversion method when forming a printed product 6 including a convex region 201 having a three-dimensional shape and a non-convex region 202 recessed more than the convex region 201, and includes a data acquisition step S10 of acquiring image data D0 of an image to be printed, a data separation step S20 of acquiring, from the image data D0, image data D0a corresponding to the convex region 201 and image data D0b corresponding to the non-convex region 202, respectively, a first color conversion step S30A of performing a first color conversion process C1 on the image data D0a corresponding to the convex region 201 to obtain print data D2a of an image corresponding to the convex region 201, and a second color conversion step S30B of performing a second color conversion process C2 different from the first color conversion process C1 on the image data D0b corresponding to the non-convex region 202 to obtain print data D2b of an image corresponding to the non-convex region 202.

[0047] According to such a method, by performing the first color conversion process C1 on the image data D0a corresponding to the convex region 201 and performing the second color conversion process C2 different from the first color conversion process C1 on the image data D0b corresponding to the non-convex region 202, printing with different colors can be performed on the convex region 201 and the non-convex region 202. By this printing with different colors, the color difference caused by the difference between the convex region 201 and the non-convex region 202 (here, for example, the presence or absence of the anti-foaming ink I2, but not limited thereto) can be canceled, and the color difference between the convex region 201 and the non-convex region 202 in the printed product 6 can be reduced.

[0048] Specifically, the difference between the color when printing is performed on the convex region 201 by executing the print data obtained by performing the first color conversion process C1 on a predetermined color and the color when printing is performed on the non-convex region 202 by executing the print data obtained by performing the second color conversion process C2 on the predetermined color is smaller than the color difference between the convex region 201 and the non-convex region 202 when printing is performed on the convex region 201 and the non-convex region 202 by executing the print data obtained by performing a common color conversion on the predetermined color. According to the relationship between the first color conversion process C1 and the second color conversion process C2, the colors of the convex region 201 and the non-convex region 202 can be made closer than in the conventional method of performing the same color conversion process on the colors of the convex region 201 and the non-convex region 202.

[0049] In this embodiment, the first color conversion process C1 includes step S31A, which converts image data D0a corresponding to the convex region 201 using an input ICC profile Pi common to the second color conversion process C2 to obtain color value data D1a corresponding to the convex region 201, and step S32A, which converts the color value data D1a corresponding to the convex region 201 using a first output ICC profile Po1 to obtain print data D2a of the image corresponding to the convex region 201. The second color conversion process C2 includes step S31B, which converts image data D0b corresponding to the non-convex region 202 using a common input ICC profile Pi to obtain color value data D1b corresponding to the non-convex region 202, and step S32B, which converts the color value data D1b corresponding to the non-convex region 202 using a second output ICC profile Po2 different from the first output ICC profile Po1 to obtain print data D2b of the image corresponding to the non-convex region 202. According to this method, by using a common input ICC profile Pi, the desired color (represented by the color values ​​obtained by the conversion using the common input ICC profile Pi) can be achieved in both the convex region 201 and the non-convex region 202.

[0050] [Second Embodiment] In the second embodiment, a common output ICC profile (B2A table) is used for the first color conversion process C1 and the second color conversion process C2, while different input ICC profiles (A2B table) are used. In the following description of the second embodiment, the same reference numerals as in the first embodiment are used for members, elements, processes, etc. that perform functions common to the first embodiment. Also, redundant explanations will be omitted or simplified as appropriate. The same applies to other embodiments.

[0051] Figure 7 is a flowchart showing an example of a color conversion process according to the second embodiment. The data acquisition step S10 and data separation step S20 in Figure 7 are the same as in Figure 6. As shown in Figure 7, in this embodiment, the first color conversion process C1 includes the step S31C of converting image data D0a corresponding to the convex region 201 with a first input ICC profile Pi1 to obtain color value data D3a corresponding to the convex region 201, and the step S32C of converting the color value data D3a corresponding to the convex region 201 with an output ICC profile Po common to the second color conversion process C2 to obtain print data D4a of the image corresponding to the convex region 201. The second color conversion process C2 includes the steps of: S31D, which converts the image data D0b corresponding to the non-convex region 202 using a second input ICC profile Pi2 different from the first input ICC profile Pi1 to obtain color value data D3b corresponding to the non-convex region 202; and S32D, which converts the color value data D3b corresponding to the non-convex region 202 using an output ICC profile Po common to the first color conversion process C1 to obtain print data D4b of the image corresponding to the non-convex region 202.

[0052] In the step of creating the first input ICC profile Pi1 and the second input ICC profile Pi2, multiple color patches 301A and color patches 301B, similar to those in Figure 5, are printed. In this embodiment, color patches 301A and color patches 301B are printed based on print data obtained by color-converting the original image using a common input ICC profile and a common output ICC profile. Subsequently, the color values ​​of the multiple color patches 301A and 301B are measured in the same manner as in step S02 of the first embodiment. The first input ICC profile Pi1 and the second input ICC profile Pi2 are created such that the measured color values ​​of color patches 301A and color patches 301B, which have common ink values ​​in the original image, are close to each other. However, the method of creating the first input ICC profile Pi1 and the second input ICC profile Pi2 is not limited to this.

[0053] According to this method, the output ICC profile of printer 10 is used as a common output ICC profile Po. Therefore, it is not necessary to create two output ICC profiles for each printer (there may be cases where the printer is changed or there are multiple printers). According to this method, even if there are multiple printers, only two input ICC profiles are needed: the first input ICC profile Pi1 and the second input ICC profile Pi2.

[0054] It should be noted that the input ICC profile and output ICC profile for the first color conversion process C1 and the second color conversion process C2 are not necessarily different. In that case, the input ICC profile and output ICC profile for the first color conversion process C1 are created such that the color values ​​measured for color patches 301A and 301B, which have common ink values ​​in the original image, are close to each other, and the input ICC profile and output ICC profile for the second color conversion process C2 may be created independently of that.

[0055] [Third Embodiment] In the third embodiment, the image data D0a of the convex region 201 and the image data D0b of the non-convex region 202 are converted using a common input ICC profile and a common output ICC profile. Subsequently, the ink value of the obtained non-convex region 202 is corrected.

[0056] Figure 8 is a flowchart showing an example of a color conversion process according to the third embodiment. The data acquisition step S10 and data separation step S20 in Figure 8 are the same as in Figures 6 and 7. Note that the data separation step S20 may be performed after steps S32E and S32F, which will be described later. As shown in Figure 8, in this embodiment, the first color conversion process C1 includes step S31E, which converts image data D0a corresponding to the convex region 201 using an input ICC profile Pi3 common to the second color conversion process C2 to obtain color value data D5a corresponding to the convex region 201, and step S32E, which converts the color value data D5a corresponding to the convex region 201 using an output ICC profile Po3 common to the second color conversion process C2 to obtain ink value data D6a. In this embodiment, the ink value data D6a becomes the print data corresponding to the convex region 201.

[0057] The second color conversion process C2 includes the steps of: S31F, which converts image data D0b corresponding to the non-convex region 202 using an input ICC profile Pi3 common to the first color conversion process C1 to obtain color value data D5b corresponding to the non-convex region 202; and S32F, which converts color value data D5b corresponding to the non-convex region 202 using an output ICC profile Po3 common to the first color conversion process C1 to obtain ink value data D6b.

[0058] In the method according to this embodiment, the second color conversion process C2 further includes step S33F, which corrects the obtained ink value data D6b to obtain print data D7b of an image corresponding to the non-convex region 202. The correction value in step S33F is determined from the difference between the color values ​​of a plurality of color patches 301A measured in the same manner as in step S02 of the first embodiment and the color values ​​of a plurality of color patches 301B measured in the same manner as in step S02 of the first embodiment. With this method, the same effects as in the first and second embodiments can be achieved without changing the ICC profile.

[0059] Furthermore, the first color conversion process C1 may also include a step of correcting the ink value data obtained through a common input ICC profile and a common output ICC profile.

[0060] [Other Embodiments] Several preferred embodiments have been described above. However, the color conversion method and image processing apparatus for realizing it of the present invention are not limited to the embodiments described above. For example, the printed output 6 is not limited to having all of the convex regions 201 at the same height. In that case, different color conversion processes may be performed on multiple parts of the convex region 201 that have different heights.

[0061] Figure 9 is a schematic cross-sectional view of a printed product 6 that includes a plurality of protrusions 201a and 201b. In the printed product 6 shown in Figure 9, the convex region 201 includes a plurality of protrusions 201a and 201b of different heights. In this case, the data separation step S20 may include a step of acquiring a plurality of image data corresponding to each of the plurality of protrusions 201a and 201b. The first color conversion step S30A may include a step of performing different color conversions on the plurality of image data corresponding to the plurality of protrusions 201a and 201b to obtain a plurality of print data corresponding to each of the plurality of protrusions 201a and 201b. In this case, the color conversion on the plurality of image data corresponding to the plurality of protrusions 201a and 201b is different from the color conversion on the image data corresponding to the non-protrusion region 202. The method of performing different color conversions on the plurality of protrusions 201a and 201b may be a method of using different input ICC profiles, a method of using different output ICC profiles, or a method of correcting the print data. According to this method, when the convex region 201 includes multiple convex parts 201a, 201b of different heights, the colors of the multiple convex parts 201a, 201b and the non-convex region 202 can be matched more precisely. The number of convex parts of different heights included in the convex region 201 is not particularly limited and may be three or more.

[0062] A printed product including a convex region having a three-dimensional shape and a non-convex region that is recessed compared to the convex region is not limited to a printed product 6 in which a part of the foamy recording medium 5 is foamed and expanded, while foaming of the other part is suppressed. In the above embodiment, the case in which foam-suppressing ink I2 is used was described, but the convex and non-convex regions may also be formed using foam-promoting ink that promotes foaming. In this case, the region in which the foam-promoting ink is ejected will foam and rise, while the region in which it is not ejected will not foam or rise. A printed product including a convex and non-convex region may, for example, be a printed product in which a convex region is formed by laminating ink layers. Alternatively, a printed product including a convex and non-convex region may be a printed product in which printing is applied to a recording medium in which a convex and non-convex region has been formed by, for example, cutting or the like.

[0063] Unless otherwise specified, the embodiments described above do not limit the present invention.

[0064] 1 Printing system 5 Recording medium 6 Printed output 10 Inkjet printer 100 Image processing device 110 Data acquisition unit 120 Data separation unit 131 First color conversion unit 132 Second color conversion unit 140 Data transmission unit 201 Convex region 201a, 201b Convex region 202 Non-convex region C1 First color conversion process C2 Second color conversion process D0 Image data D0a Image data of the convex region D0b Image data of the non-convex region D1a Color value data of the convex region D1b Color value data of the non-convex region D2a Print data of the convex region D2b Print data of the non-convex region I1 Color ink I2 Foam suppression ink Pi Common input ICC profile Pi1 First input ICC profile Pi2 Second input ICC profile Po Common output ICC profile Po1 First output ICC profile Po2 Second output ICC profile S10 Data acquisition process S20 Data separation process S30A First color conversion process S30B Second color conversion process

Claims

1. A color conversion method for forming a printed product that includes a convex region having a three-dimensional shape and a non-convex region that is recessed compared to the convex region, comprising: a data acquisition step of acquiring image data of an image to be printed; a data separation step of acquiring from the image data image data corresponding to the convex region and image data corresponding to the non-convex region, respectively; a first color conversion step of performing a first color conversion on the image data corresponding to the convex region to obtain print data of the image corresponding to the convex region; and a second color conversion step of performing a second color conversion different from the first color conversion on the image data corresponding to the non-convex region to obtain print data of the image corresponding to the non-convex region.

2. The color conversion method according to claim 1, wherein the difference between the color obtained when printing on the convex region using the print data obtained by performing the first color conversion on a predetermined color and the color obtained when printing on the non-convex region using the print data obtained by performing the second color conversion on the predetermined color is smaller than the difference between the colors of the convex region and the non-convex region when printing on the convex region and the non-convex region using print data obtained by performing a common color conversion on the predetermined color.

3. The color conversion method according to claim 1 or 2, wherein the first color conversion includes the steps of: converting image data corresponding to the convex region with an input ICC profile common to the second color conversion to obtain color value data corresponding to the convex region; and converting the color value data corresponding to the convex region with a first output ICC profile to obtain print data of the image corresponding to the convex region, and the second color conversion includes the steps of: converting image data corresponding to the non-convex region with the common input ICC profile to obtain color value data corresponding to the non-convex region; and converting the color value data corresponding to the non-convex region with a second output ICC profile different from the first output ICC profile to obtain print data of the image corresponding to the non-convex region.

4. The color conversion method according to claim 1 or 2, wherein the first color conversion includes the steps of: converting image data corresponding to the convex region with a first input ICC profile to obtain color value data corresponding to the convex region; and converting the color value data corresponding to the convex region with an output ICC profile common to the second color conversion to obtain print data of the image corresponding to the convex region, and the second color conversion includes the steps of: converting image data corresponding to the non-convex region with a second input ICC profile different from the first input ICC profile to obtain color value data corresponding to the non-convex region; and converting the color value data corresponding to the non-convex region with the common output ICC profile to obtain print data of the image corresponding to the non-convex region.

5. The color conversion method according to any one of claims 1 to 4, wherein the convex region includes a plurality of convex parts of different heights, the data separation step includes a step of acquiring a plurality of image data corresponding to each of the plurality of convex parts, and the first color conversion step includes a step of performing different color conversions on the plurality of image data corresponding to the plurality of convex parts to obtain a plurality of print data corresponding to each of the plurality of convex parts.

6. A printing method comprising: discharging foam-suppressing ink onto a portion of a recording medium that foams when heated, forming the convex region by foaming due to heating of the recording medium, and forming the non-convex region on the portion of the recording medium from which the foam-suppressing ink was dispensed, the method comprising: each step of the color conversion method according to any one of claims 1 to 5; discharging color ink onto the portion of the recording medium corresponding to the convex region based on print data of an image corresponding to the convex region obtained by the color conversion method; discharging the foam-suppressing ink and the color ink onto the portion of the recording medium corresponding to the non-convex region based on print data of an image corresponding to the non-convex region obtained by the color conversion method; and heating the recording medium.

7. An image processing apparatus comprising: a data acquisition unit for acquiring image data of an image to be printed; a data separation unit for acquiring image data corresponding to the convex region and image data corresponding to the non-convex region from the image data acquired by the data acquisition unit when creating print data including a convex region having a three-dimensional shape and a non-convex region that is recessed compared to the convex region; a first color conversion unit for performing a first color conversion on the image data corresponding to the convex region to create print data of the image corresponding to the convex region; and a second color conversion unit for performing a second color conversion different from the first color conversion on the image data corresponding to the non-convex region to create print data of the image corresponding to the non-convex region.

8. The image processing apparatus according to claim 7, wherein the first color conversion unit and the second color conversion unit perform the first and second color conversions such that the difference between the color obtained when printing on the convex region using print data obtained by performing the first color conversion on a predetermined color and the color obtained when printing on the non-convex region using print data obtained by performing the second color conversion on the predetermined color is smaller than the difference between the colors of the convex region and the non-convex region when printing on the convex region and the non-convex region using print data obtained by performing a common color conversion on the predetermined color.

9. The image processing apparatus according to claim 7 or 8, wherein the first color conversion unit is configured to, in the first color conversion, convert image data corresponding to the convex region using an input ICC profile common to the second color conversion to obtain color value data corresponding to the convex region, and convert the color value data corresponding to the convex region using a first output ICC profile to obtain print data of the image corresponding to the convex region, and the second color conversion unit is configured to, in the second color conversion, convert image data corresponding to the non-convex region using the common input ICC profile to obtain color value data corresponding to the non-convex region, and convert the color value data corresponding to the non-convex region using a second output ICC profile different from the first output ICC profile to obtain print data of the image corresponding to the non-convex region.

10. The image processing apparatus according to claim 7 or 8, wherein the first color conversion unit is configured to, in the first color conversion, convert image data corresponding to the convex region with a first input ICC profile to obtain color value data corresponding to the convex region, and convert the color value data corresponding to the convex region with an output ICC profile common to the second color conversion to obtain print data of the image corresponding to the convex region, and the second color conversion unit is configured to, in the second color conversion, convert image data corresponding to the non-convex region with a second input ICC profile different from the first input ICC profile to obtain color value data corresponding to the non-convex region, and convert the color value data corresponding to the non-convex region with the common output ICC profile to obtain print data of the image corresponding to the non-convex region.

11. The image processing apparatus according to any one of claims 7 to 10, wherein the convex region includes a plurality of convex portions of different heights, the data separation unit is configured to acquire a plurality of image data corresponding to each of the plurality of convex portions, and the first color conversion unit is configured to perform different color conversions on the plurality of image data corresponding to the plurality of convex portions to obtain a plurality of print data corresponding to each of the plurality of convex portions.

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