Color conversion device, color conversion table creation device, and program

Abstract

To easily obtain an image having properties desired by a user, compared with a case where a uniform conversion ratio is set, which is to convert a signal value of a first color space into a spot color signal in a signal value of a second color space.SOLUTION: A color conversion device comprises a processor. When the processor converts a signal value of a first color space representing an image into a signal value of a second color space including YMCK signals corresponding to the usage of color materials of YMCK colors and a spot color signal corresponding to the usage of a color material of a spot color that is a color other than the YMCK colors, the processor sets a spot color conversion ratio that is a ratio to convert the signal value of the first color space into the spot color signal according to the properties of an image printed by using the signal value of the second color space.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a color conversion device, a color conversion table creation device, and a program. [Background technology]

[0002] Patent Document 1 discloses a color conversion device that uses a GCR conversion table to replace multiple chromatic colorants, C ink, M ink, and Y ink, with K ink when converting an input image signal into a device color signal appropriate for printing. This color conversion device evaluates the color reproduction characteristics using the GCR conversion table and creates an image for visualizing the evaluation results. Furthermore, Patent Document 2 discloses a print control device that selects a color material set to be used for printing in accordance with printing performance requirements, and creates a conversion profile that converts image data from a first color space to a second color space expressed in terms of the amount of each color material that makes up the color material set. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-205166 A [Patent Document 2] JP 2008-263579 A Summary of the Invention [Problem to be solved by the invention]

[0004] When signal values ​​in a first color space representing an image are converted into signal values ​​in a second color space including YMCK signals, which are signal values ​​of YMCK colors, and spot color signals, which are signal values ​​of spot colors other than YMCK colors, and the image is printed using the signal values ​​in the second space, the properties of the printed image differ depending on the conversion ratio at which the signal values ​​in the first color space are converted into spot color signals in the signal values ​​in the second color space. If the conversion ratio at which the signal values ​​in the first color space are converted into spot color signals in the signal values ​​in the second color space is uniform when the signal values ​​in the first color space representing an image are converted into signal values ​​in the second color space, the properties of the printed image may not be as desired by the user. The present invention aims to make it easier for users to obtain images with the characteristics they desire, compared to when a uniform conversion ratio is used to convert signal values ​​in a first color space to special color signals in signal values ​​in a second color space. [Means for solving the problem]

[0005] The invention described in claim 1 is a color conversion device that includes a processor, and when converting signal values ​​in a first color space representing an image into signal values ​​in a second color space including a YMCK signal corresponding to the usage amount of color materials of YMCK colors and a spot color signal corresponding to the usage amount of color materials of a spot color that is a color other than YMCK colors, the processor sets a spot color conversion ratio, which is the ratio at which the signal values ​​of the first color space are converted into the spot color signals, in accordance with the properties of an image to be printed using the signal values ​​of the second color space. The invention described in claim 2 is a color conversion device described in claim 1, in which the processor sets a K color conversion ratio, which is the ratio for converting signal values ​​of the first color space into K color signals, and the spot color conversion ratio according to the characteristics of an image to be printed using signal values ​​of the second color space. The invention described in claim 3 is a color conversion device described in claim 2, in which the processor sets the spot color conversion ratio and the K color conversion ratio in conjunction with each other depending on the characteristics of the image to be printed using signal values ​​of the second color space. The invention described in claim 4 is a color conversion device described in claim 3, wherein the processor changes the K color conversion ratio so as to increase the amount of K color material used when changing the spot color conversion ratio so that the amount of the spot color material used is reduced below a predetermined reference value. The invention described in claim 5 is a color conversion device described in claim 3 or 4, in which the processor does not change the K color conversion ratio when changing the spot color conversion ratio so that the usage amount of the spot color colorant increases above a predetermined reference value. The invention described in claim 6 is the color conversion device described in claim 1, in which the processor, when converting signal values ​​of the first color space into signal values ​​of the second color space including the YMCK signal and a plurality of spot color signals corresponding to the usage amounts of a plurality of spot color materials, individually sets a plurality of spot color conversion ratios, which are ratios for converting the signal values ​​of the first color space into each of the spot color signals, depending on the properties of the image to be printed using the signal values ​​of the second color space. The invention described in claim 7 is a color conversion device described in claim 1, in which the processor displays an image on a display unit that displays information, the image showing the correspondence between the amount of color material used of the spot color and the properties of the image printed using the signal values ​​of the second color space. The invention described in claim 8 is a color conversion device described in claim 7, in which the processor acquires information regarding the usage amount of the spot color colorant in response to an operation on the displayed image, and sets the spot color conversion ratio based on the usage amount of the spot color colorant. The invention described in claim 9 is the color conversion device described in claim 8, wherein the processor sets the amount of K color material used in conjunction with the amount of the spot color color material obtained in response to an operation on the display image, then sets the amount of the spot color color material or the amount of the K color material used individually in response to the operation on the display image, sets the spot color conversion ratio based on the amount of the spot color color material used, and sets a K color conversion ratio, which is the ratio for converting the signal value of the first color space to a K color signal, based on the amount of the K color material used. The invention described in claim 10 is a color conversion device described in claim 1, in which the processor sets the spot color conversion ratio for converting the signal values ​​of the first color space representing a specific area that satisfies predetermined conditions in an image printed using signal values ​​of the second color space into the spot color signal, depending on the characteristics of the specific area. The invention described in claim 11 is a color conversion table creation device that includes a processor, which creates a color conversion table that converts signal values ​​in a first color space representing an image into signal values ​​in a second color space that includes a YMCK signal corresponding to the usage amount of color materials of YMCK colors and a spot color signal corresponding to the usage amount of a spot color color other than YMCK colors, and in which the spot color conversion ratio, which is the ratio at which the signal value of the first color space is converted into the spot color signal, is determined according to the properties of an image to be printed using the signal values ​​of the second color space. The invention described in claim 12 is a program that realizes a function for a computer to set a spot color conversion ratio, which is the ratio at which the signal values ​​of the first color space representing an image are converted into spot color signals, in accordance with the properties of an image to be printed using the signal values ​​of the second color space, when converting signal values ​​of a first color space representing an image into signal values ​​of a second color space including a YMCK signal corresponding to the usage amount of color materials of YMCK colors and a spot color signal corresponding to the usage amount of color materials of a spot color other than YMCK colors. Effect of the Invention

[0006] According to the invention described in claim 1, it is possible to more easily obtain an image having the characteristics desired by the user, compared to a case where a uniform conversion ratio is used to convert signal values ​​in a first color space to special color signals in signal values ​​in a second color space. According to the invention described in claim 2, it is easier to obtain an image having the characteristics desired by the user, compared to when the conversion ratio for converting the signal value of the first color space to the K color signal in the signal value of the second color space is uniform. According to the invention described in claim 3, an image having the characteristics desired by the user can be obtained with simpler operations than when the spot color conversion ratio and the K color conversion ratio are set without being linked. According to the invention described in claim 4, when the spot color conversion ratio is changed so that the amount of spot color material used is reduced below a reference value, it is easier to improve the light fastness of the image and the cost required to print the image, which are image properties, compared to when the K color conversion ratio is changed so that the amount of K color material used is reduced. According to the invention described in claim 5, when the spot color conversion ratio is changed so that the amount of spot color material used is increased above a reference value, it is easier to improve the graininess of the image as an image property, compared to when the K color conversion ratio is changed so that the amount of K color material used is increased. According to the invention as recited in claim 6, it is possible to more easily obtain an image having the properties desired by the user, compared to a case in which a plurality of spot color conversion ratios are set uniformly. According to the invention described in claim 7, it becomes easier for the user to understand the difference in image properties resulting from changing the amount of spot color material used, compared to a case in which the display unit does not display the correspondence between the amount of spot color material used and the image properties. According to the eighth aspect of the invention, the user can set the amount of the spot color material to be used by manipulating the displayed image while checking on the display unit the correspondence between the amount of the spot color material to be used and the properties of the image. According to the invention described in claim 9, it is possible to more easily obtain an image having the characteristics desired by the user, compared to a case in which information regarding the amount of spot color material used or the amount of K color material used is not obtained separately. According to the invention described in claim 10, it is possible to more easily obtain an image having the characteristics desired by the user, compared to a case in which the spot color conversion ratio for converting a signal value of a first color space representing a specific region into a spot color signal is not set according to the characteristics of the specific region. According to the invention described in claim 11, it is possible to more easily obtain an image having the characteristics desired by the user, compared to a case where the conversion ratio for converting the signal values ​​in the first color space to the feature color signals in the signal values ​​in the second color space is uniform. According to the invention described in claim 12, it is possible to more easily obtain an image having the characteristics desired by the user, compared to a case where the conversion ratio for converting the signal values ​​in the first color space to the feature color signals in the signal values ​​in the second color space is uniform. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a printing system to which an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a functional block diagram of a color conversion device. [Diagram 3] 13 is a diagram showing an example of a selection screen displayed on an operation display unit by a profile generating unit of the color conversion device. FIG. [Figure 4] 13 is a diagram showing the relationship between the spot color toner amount and the K color toner amount selected in conjunction with an operation on a toner amount selection unit. FIG. [Diagram 5] FIG. 4 illustrates the selection screen after the knob of the toner amount selection section has been moved to the left by a user operation from the state illustrated in FIG. 3. [Figure 6] 11 is a flowchart showing an example of a color transformation profile generation process performed by a profile generation unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating the configuration of a printing system 100 to which this embodiment is applied. The printing system 100 shown in the figure includes an input device 10, a printing device 20, and a color conversion device 30. The input device 10, the printing device 20, and the color conversion device 30 are connected to each other so as to be able to communicate with each other. A LAN (Local Area Network) or the Internet, for example, is used as the network connecting the input device 10, the printing device 20, and the color conversion device 30. However, the network may also be a combination of a LAN and the Internet.

[0009] The input device 10 is configured by a computer device. The input device 10 inputs image data to be used for printing by the printing device 20 to the color conversion device 30.

[0010] The printing device 20 prints an image on paper, which is an example of a recording medium, based on image data that is input by the input device 10 and has been color converted by the color conversion device 30. The printing device 20 includes a printing unit 21 that performs printing operations, and a print control unit 22 that controls the operation of the printing unit 21 based on the image data generated by the color conversion device 30.

[0011] The printing unit 21 prints an image on a sheet by, for example, an electrophotographic method. The printing unit 21 of this embodiment prints an image on a sheet using toners of yellow (Y), magenta (M), cyan (C), and black (K) (hereinafter, these colors may be referred to as normal colors) and toners of special colors different from the normal colors. The toners are an example of color materials used in forming an image. Here, the special colors are colors different from the normal colors, and examples of the special colors include colors that are difficult to achieve with toners of normal colors such as yellow, magenta, cyan, and black. Examples of such special colors include, but are not limited to, fluorescent pink, fluorescent yellow, white, light cyan, orange, violet, and green, as well as metallic colors such as gold and silver colored using metal pigments. In this embodiment, an example will be described in which the printing unit 21 forms an image using toner of fluorescent pink (P) as a special color in addition to the normal colors.

[0012] The printing format and type of color material of the printing unit 21 are not particularly limited as long as the printing unit 21 forms an image on paper using color materials of normal colors, yellow (Y), magenta (M), cyan (C), and black (K), and one or more special color materials. The printing unit 21 may print an image on paper by the above-mentioned electrophotographic method, as well as by inkjet method, thermal transfer method, offset printing, etc. In the following description, the normal colors yellow (Y), magenta (M), cyan (C), and black (K) may be referred to as YMCK colors. Also, the YMCK colors and the special color fluorescent pink (P) used in printing by the printing device 20 may be collectively referred to as YMCKP colors.

[0013] The color conversion device 30 is an example of a color conversion device or a color conversion table creation device, and is configured by a computer device. The color conversion device 30 may be a single physical computer, or may be realized by distributed processing using multiple computers. The color conversion device 30 may be configured as a shared server that provides a so-called cloud service, or may be configured as an on-premise server. Furthermore, the color conversion device 30 may be built into the printing device 20 as a part of the printing device 20 .

[0014] In the printing system 100 of this embodiment, image data expressed in signal values ​​of the RGB color space is input from the input device 10 to the color conversion device 30. The color conversion device 30 converts the input signal values ​​of the RGB color space into signal values ​​of the YMCKP color space used in the printing device 20. The color conversion device 30 then outputs the image data expressed in signal values ​​of the YMCKP color space to the printing device 20. The printing device 20 forms an image on paper using Y, M, C, K and P toners based on the image data acquired from the color conversion device 30. The signal values ​​in the YMCKP color space include YMCK color signal values ​​corresponding to the amounts of YMCK color toner used, and P color signal values ​​corresponding to the amount of P color toner used, which is a spot color. The YMCK color signal values ​​are an example of a YMCK color signal, and the P color signal value is an example of a spot color signal. The signal values ​​of each color in the YMCKP color space correspond to the amount of each color toner used in the printing unit 21 of the printing device 20. The signal values ​​of each color in the YMCKP color space are represented by a numerical value ranging from 0% to 100%, for example.

[0015] FIG. 2 is a functional block diagram of the color conversion device 30. As shown in FIG. The color conversion device 30 includes a color conversion unit 31 that performs color conversion processing of image data input from the input device 10, a profile generation unit 40 that generates a color conversion profile used in the color conversion processing by the color conversion unit 31, a profile storage unit 33 that stores the color conversion profile generated by the profile generation unit 40, and an operation display unit 35 that displays information to a user and accepts information input by user operation. The operation display unit 35 is an example of a display unit.

[0016] Here, the functions of the color conversion unit 31 and the profile generation unit 40 in the color conversion device 30 are realized by a CPU 30A as an example of a processor. The CPU 30A reads out a program stored in a ROM (Read Only Memory) 30B, and executes the program using a RAM (Random Access Memory) 30C as a working area. The program executed by the CPU 30A may be provided to the color conversion device 30 in a state where it is stored in a computer-readable recording medium such as a magnetic recording medium (magnetic tape, magnetic disk, etc.), an optical recording medium (optical disk, etc.), a magneto-optical recording medium, or a semiconductor memory. The program executed by the CPU 30A may also be downloaded to the color conversion device 30 using a communication means such as the Internet.

[0017] In addition, in this embodiment, the functions of the color conversion unit 31 and the profile generation unit 40 in the color conversion device 30 are realized by software, but this is not limited to this and may be realized by, for example, an ASIC (Application Specific IC).

[0018] The profile generation unit 40 generates a color conversion profile that converts signal values ​​in an RGB color space that represents image data input from the input device 10 into signal values ​​in a YMCKP color space that can be reproduced by the printing device 20. The color conversion profile generated by the profile generation unit 40 is an example of a color conversion table that converts signal values ​​in a first color space that represents an image into signal values ​​in a second color space that includes YMCK signals corresponding to the usage amounts of color materials of YMCK colors and spot color signals corresponding to the usage amounts of color materials of spot colors that are colors other than YMCK colors.

[0019] The profile generating unit 40 includes a first conversion unit 41 that converts signal values ​​in the RGB color space into signal values ​​in a color space that is independent of devices such as the input device 10 and the printing device 20. The first conversion unit 41 of this embodiment converts signal values ​​in the RGB color space into signal values ​​in a color space that is independent of devices such as the input device 10 and the printing device 20. * a * b * Converts the signal value into a color space. * a * b * The color space is lightness L * and chromaticity a * and chromaticity b * It is expressed in a Cartesian coordinate color space with the axes and . RGB color space or L * a * b * The color space is an example of a first color space.

[0020] The profile generating unit 40 also converts the L * a * b * The signal values ​​in the color space are * a * b * The color gamut compression unit 42 compresses the signal values ​​to those in the color gamut of the printing device 20 in the color space.

[0021] The profile generator 40 also converts the L * a * b *A second conversion unit 43 is provided for converting the signal values ​​of the color space into signal values ​​of the YMCKP color space reproducible by the printing device 20. The YMCKP color space is an example of the second color space. The second conversion unit 43 determines the signal value of K color in the signal values ​​of the YMCKP color space based on the conversion ratio to the signal value of K color set by a K color setting unit 45 described later. The second conversion unit 43 also determines the signal value of P color in the signal values ​​of the YMCKP color space based on the conversion ratio to the signal value of P color set by a spot color setting unit 46 described later.

[0022] In addition, the profile generator 40 * a * b * A K color setting unit 45 is provided to set the conversion ratio to the K color signal value when converting the signal value of the color space into the signal value of the YMCKP color space. * a * b * The conversion ratio to the signal value of K color when converting the signal value of a color space into the signal value of the YMCKP color space is represented as the K color conversion ratio.

[0023] Here, in the printing device 20 that prints an image using color materials including YMCK colors, a part of the YMC color materials used in printing can be replaced with a K color material. The K color conversion ratio is L * a * b * This refers to the ratio at which YMC color signal values ​​are replaced with K color signal values ​​when converting color space signal values ​​to YMCKP color space signal values. In this embodiment, the K color conversion ratio is expressed by a value between 0% and 100%, for example. A K color conversion ratio of 0% refers to a case where the signal value of K color is the lowest among the signal values ​​in the YMCKP color space that reproduces a certain color. A K color conversion ratio of 100% refers to a case where the signal value of K color is the highest among the signal values ​​in the YMCKP color space that reproduces a certain color.

[0024] In addition, the profile generator 40 * a * b *The spot color setting unit 46 is provided for setting a conversion ratio to a spot color signal value when converting a signal value in the color space into a signal value in the YMCKP color space. In this embodiment, the spot color setting unit 46 sets the conversion ratio to a spot color signal value as follows: * a * b * Sets the conversion ratio to the P color signal value when converting the signal value of the color space to the signal value of the YMCKP color space. * a * b * The conversion ratio to the spot color signal value when converting the signal value of the color space to the signal value of the YMCKP color space is referred to as the spot color conversion ratio.

[0025] Here, in the printing device 20 that prints an image using color materials of a special color P in addition to the normal colors YMCK, a part of the color materials of the YMCK colors can be replaced with the color materials of the P color. * a * b * It means the ratio at which YMCK color signal values ​​are replaced with P color signal values ​​when converting color space signal values ​​to YMCKP color space signal values. Furthermore, in the printing device 20, even if the amounts of YMCK color materials replaced with P color materials differ, it is possible to reproduce images of the same colors by adjusting the amounts of YMCK and P color materials used. In this embodiment, the spot color conversion ratio is expressed by a value between 0% and 100%, for example. A spot color conversion ratio of 0% refers to a case where the signal value of P color is the lowest among the signal values ​​in the YMCKP color space that reproduces a certain color. A spot color conversion ratio of 100% refers to a case where the signal value of P color is the highest among the signal values ​​in the YMCKP color space that reproduces a certain color.

[0026] The K color setting unit 45 and the spot color setting unit 46 cause the operation display unit 35 of the color conversion device 30 to display a selection screen 90 (see FIG. 3 described later) for selecting the amount of K color material and the amount of spot color material to be used. Then, the K color setting unit 45 acquires information on the usage amount of K color material in response to a user operation on the selection screen 90. In this embodiment, the K color setting unit 45 acquires information on the K color toner amount as an example of the information on the usage amount of K color material. Then, the K color setting unit 45 sets a K color conversion ratio based on the acquired information on the K color toner amount. Furthermore, the spot color setting unit 46 acquires information on the usage amount of spot color material in response to a user operation on the selection screen 90. In this embodiment, the spot color setting unit 46 acquires information on the P color toner amount as an example of the information on the usage amount of spot color color material. Then, the spot color setting unit 46 sets a spot color conversion ratio based on the acquired information on the P color toner amount.

[0027] Incidentally, in the printing device 20 that prints an image using color materials of normal colors YMCK and color materials of special colors, as described above, even if the amount of the color materials of the special colors used differs, it is possible to reproduce an image of the same color. * a * b * Even if the spot color conversion ratios used when converting signal values ​​in a color space into signal values ​​in a YMCKP color space are different, the printing device 20 can reproduce images of the same colors. Furthermore, as described above, the printing device 20 can reproduce an image of the same color even if the amounts of Y, M, and C color materials substituted with the K color material are different. * a * b * Even if the K color conversion ratio used when converting signal values ​​in a color space into signal values ​​in a YMCKP color space is different, the printing device 20 can reproduce images of the same colors. In this embodiment, the images printed by the printing device 20 having the same color mean that the signal values ​​obtained when the images are color-measured by a color measuring device (not shown) are the same.

[0028] Here, even if the reproduced colors are the same, the properties of the images printed by the printing device 20 may differ depending on the spot color conversion ratio or K color conversion ratio in the color conversion device 30. In addition, the amounts of YMCK color materials and P color material used to print the image in the printing device 20, the total amount of color materials used to print the image, etc. differ depending on the spot color conversion ratio or K color conversion ratio. This may result in the properties of the images printed by the printing device 20 differing.

[0029] Image properties that change depending on the spot color conversion ratio or K color conversion ratio include the lightfastness of the image. Image lightfastness refers to the resistance of an image to deterioration due to exposure to light. In general, a P color material, which is a spot color, is more susceptible to deterioration such as fading due to exposure to light than a YMCK color material, which is a normal color. In addition, when YMC color materials are replaced with K color materials, the total amount of color materials used in the image is reduced, and deterioration such as fading due to exposure to light becomes less noticeable. For this reason, the lightfastness of an image tends to be better the lower the spot color conversion ratio. In addition, the lightfastness of an image tends to be better the higher the K color conversion ratio.

[0030] Furthermore, the cost required to print an image can be cited as an image property that changes depending on the spot color conversion ratio or K color conversion ratio. In general, spot color materials tend to have a higher unit price than color materials of normal colors YMCK. For this reason, the cost required to print an image tends to increase the more spot color materials are used. Furthermore, when YMC color materials are replaced with K color materials, the total amount of color materials used in the image is reduced, so the cost required to print an image tends to decrease. Therefore, the lower the spot color conversion ratio, the more the cost required to print an image tends to decrease. Furthermore, the higher the K color conversion ratio, the more the cost required to print an image tends to decrease.

[0031] Furthermore, image gradation can be cited as an image property that changes depending on the size of the spot color conversion ratio or K color conversion ratio. Image gradation refers to the smoothness of changes in the shade of an image. Image gradation is improved when the amount of each color material in the normal colors YMCK and the spot color P does not change suddenly. For this reason, the higher the spot color conversion ratio and K color conversion ratio, the better the image gradation tends to be.

[0032] Furthermore, the image properties that change depending on the spot color conversion ratio or the K color conversion ratio include the illumination dependency of the image. The image printed by the printing device 20 may have different visible colors depending on the illumination of the environment in which the image is placed. The illumination dependency of the image is the resistance to color change due to differences in illumination. In addition, the better the illumination dependency of the image, the less likely the image will have differences in color when viewed under different illumination. Spot color materials and K color materials tend to have less differences in color due to differences in illumination compared to YMC color materials. Therefore, the higher the spot color conversion ratio, the better the illumination dependency of the image. Furthermore, the higher the K color conversion ratio, the better the illumination dependency of the image.

[0033] Moreover, the graininess of an image can be cited as an image property that changes depending on the spot color conversion ratio or the K color conversion ratio. The printing device 20 may form an image by applying color materials in dots on paper, depending on the printing method. The graininess of an image is the degree to which the dots of color materials that make up the image are less noticeable. In addition, the better the graininess of an image, the less noticeable the dots of color materials are, and the easier it is to express a smooth image. For example, when an image represents human skin or the sky, it is preferable that the graininess of the image is good. The graininess of an image tends to be better as the spot color conversion ratio is higher. Also, the graininess of an image tends to be better as the K color conversion ratio is lower.

[0034] In this way, the properties of the image printed by the printing device 20 differ depending on the spot color conversion ratio and the K color conversion ratio used when the signal values ​​of the image data input to the color conversion device 30 are converted into signal values ​​in the YMCKP color space. If the spot color conversion ratio is set to a uniform value when the signal values ​​of the image data input to the color conversion device 30 are converted into signal values ​​in the YMCKP color space, for example, the properties of the image printed by the printing device 20 may not be what the user desires. In contrast, the color conversion device 30 of this embodiment sets a spot color conversion ratio according to the properties of the image printed by the printing device 20. More specifically, the color conversion device 30 of this embodiment acquires information on the usage amount of spot color materials used in printing an image by the printing device 20 according to the properties of the image desired by the user. Then, the color conversion device 30 sets a spot color conversion ratio based on the acquired information on the usage amount of spot color materials, and generates a color conversion profile. Furthermore, the color conversion device 30 performs color conversion processing of image data input from the input device 10 using the generated color conversion profile, and outputs the image data after color conversion processing to the printing device 20.

[0035] Fig. 3 is a diagram showing an example of a selection screen 90 displayed on the operation display unit 35 by the profile generation unit 40 of the color conversion device 30. The selection screen 90 shown in Fig. 3 is used by the user to select the usage amount of spot color toner and the usage amount of K color toner in an image printed by the printing device 20. In the following description, the usage amount of spot color toner in an image printed by the printing device 20 is referred to as the spot color toner amount. Also, the usage amount of K color toner in an image printed by the printing device 20 is referred to as the K color toner amount. The spot color toner amount is an example of the usage amount of spot color color material, and the K color toner amount is an example of the usage amount of K color material.

[0036] As shown in Fig. 3, the selection screen 90 includes a toner amount selection section 91 for the user to select the spot color toner amount. The toner amount selection section 91 is configured with a slider that allows the user to select the spot color toner amount by moving the knob left and right. In addition, the user selects the spot color toner amount by moving the knob of the toner amount selection section 91 left and right. In the toner amount selection section 91 of Fig. 3, moving the knob to the left reduces the spot color toner amount selected, and moving the knob to the right increases the spot color toner amount selected.

[0037] In this embodiment, when the spot color toner amount selected by operating the toner amount selection unit 91 is changed, the selected K color toner amount is also changed in conjunction with the spot color toner amount. That is, in the selection screen 90 of this embodiment, the spot color toner amount and the K color toner amount can be selected together by operating the toner amount selection unit 91. In this example, before the user operates the toner amount selection unit 91 (for example, when the knob of the toner amount selection unit 91 is in the center as shown in FIG. 3), the spot color toner amount and K color toner amount selected by the toner amount selection unit 91 are set to predetermined reference values.

[0038] Note that the toner amount selection unit 91 is not limited to the slider shown in Fig. 3, so long as the spot color toner amount can be selected by a user operation. The toner amount selection unit 91 may be, for example, a mode in which the spot color toner amount is directly input, or a mode in which a choice indicating the magnitude of a predetermined spot color toner amount (for example, "large", "small", etc.) is selected. The same applies to a special color toner amount selection unit 95 and a K color toner amount selection unit 96, which will be described later.

[0039] FIG. 4 is a diagram showing the relationship between the spot color toner amount and the K color toner amount selected in conjunction with the operation on the toner amount selection unit 91. As shown in FIG. As described above, among the properties of an image printed by the printing device 20, the lightfastness of the image and the cost required to print the image tend to be better as the spot color conversion ratio is lower. Also, the lightfastness of the image and the cost required to print the image tend to be better as the K color conversion ratio is higher. Therefore, in this embodiment, when the knob of the toner amount selection unit 91 is moved to the left to reduce the spot color toner amount below the reference value, the K color toner amount is increased above the reference value in conjunction with the spot color toner amount.

[0040] As described above, among the properties of an image printed by the printing device 20, the image gradation, illumination dependency, and graininess tend to improve as the spot color conversion ratio increases. Also, while the image gradation and illumination dependency improve as the K color conversion ratio increases, there is a possibility that the graininess of the image may worsen when the K color conversion ratio is increased. In other words, when the spot color conversion ratio is increased, there are properties of image quality that improve and properties of image quality that deteriorate. Therefore, in this embodiment, when the knob of the toner amount selection unit 91 is moved to the right to increase the spot color toner amount above the reference value, the K color toner amount is not changed from the reference value.

[0041] In this manner, in this embodiment, both the spot color toner amount and the K color toner amount can be selected in accordance with the nature of an image that changes depending on the size of the spot color toner amount and the K color toner amount, by operating the toner amount selection unit 91. This allows the spot color toner amount and the K color toner amount to be selected by a simple operation, for example, compared to the case where the spot color toner amount and the K color toner amount are selected separately.

[0042] 3, the selection screen 90 includes a property display section 92 that shows the correspondence between the spot color toner amount selected by the toner amount selection section 91 and the property of the image printed by the printing device 20. The property display section 92 includes a first property display section 92A that shows the property of the image when the spot color toner amount is increased, and a second property display section 92B that shows the property of the image when the spot color toner amount is decreased. The first property display section 92A and the second property display section 92B of this embodiment show the image properties that become better when the amount of the spot color toner is changed, as a correspondence between the amount of the spot color toner and the image properties. More specifically, the first property display section 92A displays the wording "gradation / granularity / illumination dependency will be improved" as an example of the image properties when the amount of the spot color toner is increased. The second property display section 92B displays the wording "cost / lightfastness will be improved" as an example of the image properties when the amount of the spot color toner is decreased.

[0043] In this embodiment, the selection screen 90 includes a property display section 92, which allows the user to understand what properties the image printed by the printing device 20 will have when the spot color toner amount is changed. The user can then select the spot color toner amount using the toner amount selection section 91 while referring to the image properties displayed on the property display section 92. This makes it easier for the user to obtain an image having the desired property, as compared to a case where the selection screen 90 does not include the property display section 92, for example. The property display unit 92 may display the image property that becomes worse when the special color toner amount is changed, as a correspondence between the special color toner amount and the image property.

[0044] The selection screen 90 also includes a property notification section 93 that notifies the user that image properties will deteriorate if the spot color toner amount is changed excessively by the toner amount selection section 91. The property notification section 93 is displayed on the selection screen 90 when the spot color toner amount is changed excessively by the toner amount selection section 91. The property notification section 93 of this embodiment notifies the user that "graininess may deteriorate" when the spot color toner amount is changed by the toner amount selection section 91 to be less than a predetermined threshold value. In this embodiment, the selection screen 90 includes the property notification unit 93, so that the user can understand that the image quality will deteriorate if the spot color toner amount is changed excessively by the toner amount selection unit 91. This prevents the toner amount selection unit 91 from changing the spot color toner amount excessively when the user does not want the image quality to deteriorate. This makes it easier for the user to obtain an image with the properties he or she desires, compared to when the selection screen 90 does not include the property notification unit 93, for example.

[0045] The selection screen 90 also includes an individual selection section 94 for individually selecting the spot color toner amount and the K color toner amount. The individual selection section 94 includes a check box 941 that the user selects when individually selecting the spot color toner amount and the K color toner amount. The individual selection section 94 also includes a spot color toner amount selection section 95 for the user to individually select the spot color toner amount. The individual selection section 94 further includes a K color toner amount selection section 96 for the user to individually select the K color toner amount. The spot color toner amount selection unit 95 is configured with a slider that allows the user to select the spot color toner amount by moving the knob left and right. Similarly, the K color toner amount selection unit 96 is configured with a slider that allows the user to select the K color toner amount by moving the knob left and right.

[0046] In the selection screen 90 of this embodiment, when the check box 941 in the individual selection section 94 is not selected, the knobs in the spot color toner amount selection section 95 and the K toner amount selection section 96 move in response to an operation on the toner amount selection section 91. FIG. 5 is a diagram showing the selection screen 90 after the knob of the toner amount selection section 91 has been moved leftward by a user operation from the state shown in FIG.

[0047] As described above, when the knob of the toner amount selection unit 91 is moved to the left, the selected spot color toner amount becomes less than the reference value. Then, the knob of the spot color toner amount selection unit 95 in the individual selection unit 94 moves from the center to the left in accordance with the movement of the knob of the toner amount selection unit 91. Furthermore, when the knob of the toner amount selection unit 91 is moved to the left and the selected spot color toner amount becomes smaller than the reference value, the selected K toner amount becomes greater than the reference value in conjunction with the spot color toner amount. Then, the knob of the K toner amount selection unit 96 in the individual selection unit 94 moves from the center to the right.

[0048] In this way, on the selection screen 90 of the present embodiment, the knobs of the spot color toner amount selection section 95 and the K color toner amount selection section 96 in the individual selection section 94 move according to the spot color toner amount and the K color toner amount selected by operating the toner amount selection section 91. By checking the positions of the knobs of the spot color toner amount selection section 95 and the K color toner amount selection section 96, the user can grasp the spot color toner amount and the K color toner amount selected by operating the toner amount selection section 91.

[0049] Furthermore, on the selection screen 90, when a check box 941 in an individual selection section 94 is selected, the spot color toner amount can be individually selected by operating a spot color toner amount selection section 95. Similarly, on the selection screen 90, when a check box 941 in an individual selection section 94 is selected, the K color toner amount can be individually selected by operating a K color toner amount selection section 96. In addition, in the individual selection unit 94, moving the knob of the spot color toner amount selection unit 95 to the left reduces the spot color toner amount selected, and moving the knob to the right increases the spot color toner amount selected. Note that when the spot color toner amount selection unit 95 is operated to change the spot color toner amount, the K toner amount does not change. Similarly, in the individual selection unit 94, moving the knob of the K toner amount selection unit 96 to the left reduces the amount of K toner selected, and moving the knob to the right increases the amount of K toner selected. Note that when the K toner amount selection unit 96 is operated to change the amount of K toner, the amount of spot color toner does not change.

[0050] Returning to FIG. 3, the selection screen 90 includes an area setting section 97 for setting the amount of spot color toner in a specific area of ​​the image that satisfies predetermined conditions to a value different from that in other areas, depending on the characteristics of the specific area. There are cases where it is preferable to make the properties of a specific region in an image different from those of other regions. For example, as described above, when an image represents human skin or the like, it is preferable that the graininess of the image, which is one of the properties of the image, is good. The graininess of an image tends to be better as the amount of special color toner is increased. In this embodiment, by selecting the region setting section 97, it is possible to increase the amount of special color toner in a skin region representing human skin, which is an example of a specific region of an image that satisfies a predetermined condition. This makes it easier for the user to obtain an image with the properties he or she desires, compared to when the selection screen 90 does not include the region setting section 97.

[0051] The selection screen 90 also includes an instruction section 98 that instructs generation of a color conversion profile. When the instruction section 98 is operated by the user, the profile generation section 40 causes the K color setting section 45 to acquire information relating to the K color toner amount selected on the selection screen 90, and the spot color setting section 46 to acquire information relating to the spot color toner amount selected on the selection screen 90. The profile generation section 40 then generates a color conversion profile based on the acquired information relating to the K color toner amount and information relating to the spot color toner amount. Here, in this embodiment, the toner amount selection section 91, property display section 92, property notification section 93, individual selection section 94, area setting section 97 and instruction section 98 included in the selection screen 90 are examples of display images displayed on the display section.

[0052] Next, the process of generating a color transformation profile by the profile generating unit 40 will be specifically described. FIG. 6 is a flowchart showing an example of a color transformation profile generation process performed by the profile generation unit 40.

[0053] The profile generating unit 40 causes the K color setting unit 45 and the spot color setting unit 46 to display on the operation display unit 35 a selection screen 90 (see FIG. 3) for receiving selection of the spot color toner amount and the K color toner amount (step 101). Next, the K color setting unit 45 acquires information about the K color toner amount selected on the selection screen 90, and sets the K color conversion ratio based on this information (step 102). Moreover, the spot color setting unit 46 acquires information on the spot color toner amount selected on the selection screen 90, and sets the spot color conversion ratio based on this information (step 103).

[0054] Next, the first conversion unit 41 converts the signal values ​​in the RGB color space representing the image data input from the input device 10 into L * a * b * The signal values ​​are converted into color space signal values ​​(step 104). Next, the color gamut compression unit 42 converts the L * a * b * The signal values ​​in the color space are * a * b * The color gamut is compressed to signal values ​​in the color gamut of the printing device 20 in the color space (step 105).

[0055] Next, the second conversion unit 43 converts the L color gamut compressed in step 105 into the K color gamut using the K color conversion ratio set in step 102 and the spot color conversion ratio set in step 103. * a * b * The signal values ​​in the color space are converted into signal values ​​in the YMCKP color space that can be reproduced by the printing device 20 (step 106). More specifically, the second conversion unit 43 determines a signal value of K color in the YMCKP color space using the K color conversion ratio set in step 102. Next, the second conversion unit 43 determines a signal value of P color, which is a spot color in the YMCKP color space, using the spot color conversion ratio set in step 103. Next, the second conversion unit 43 determines a signal value of Y color, a signal value of M color, and a signal value of C color in the YMCKP color space.

[0056] The profile generating unit 40 executes the processes of steps 104 to 106 for each lattice point in the RGB color space. Next, the profile generation unit 40 generates a color conversion profile that converts the signal values ​​in the RGB color space into signal values ​​in the YMCKP color space used by the printing device 20, based on the results of the processing in steps 104 to 106 for each lattice point in the RGB color space (step 107). Then, the profile generating unit 40 stores the color transformation profile generated in step 107 in the profile storage unit 33 (step 108), and ends the series of processes.

[0057] In this way, the color conversion device 30 of this embodiment generates a color conversion profile in which the spot color conversion ratio and the K color conversion ratio are determined according to the characteristics of the image to be printed by the printing device 20. Moreover, in the color conversion device 30, the color conversion unit 31 performs color conversion processing of the image data input from the input device 10 using a color conversion profile stored in the profile storage unit 33. In addition, the color conversion unit 31 converts the signal values ​​of the RGB color space representing the image data input from the input device 10 into signal values ​​of the YMCKP color space reproducible by the printing device 20 using a color conversion profile in which a spot color conversion ratio and a K color conversion ratio are determined according to the properties of the image. Then, the color conversion device 30 outputs the image data represented by the converted signal values ​​of the YMCKP color space to the printing device 20. The printing device 20 prints an image on paper using the image data represented by the signal values ​​of the YMCKP color space acquired from the color conversion device 30. This makes it easier for images printed by printing device 20 to have the characteristics desired by the user, compared to when color conversion of image data is performed using a color conversion profile in which the spot color conversion ratio and K color conversion ratio are not determined according to the characteristics of the image.

[0058] In the above-described embodiment, an example was given in which the color conversion device 30 converts signal values ​​in the RGB color space representing image data into signal values ​​in the YMCKP color space including signal values ​​of P color corresponding to the usage amount of P color material. The special color is not limited to the above-mentioned fluorescent pink (P), but may be any color different from the normal YMCK colors.

[0059] Moreover, different types of spot colors may be used as the spot colors. In addition, the color conversion device 30 may convert the signal values ​​of the RGB color space representing the image data into signal values ​​of a color space including signal values ​​of multiple spot colors corresponding to the usage amounts of color materials of the multiple spot colors. Here, a case is considered in which the color conversion device 30 converts the signal values ​​of the RGB color space representing the image data into signal values ​​of a color space including signal values ​​of two types of spot colors, a first spot color and a second spot color, as the multiple spot colors. In the printing device 20 that prints an image using a plurality of types of spot color materials, the properties of the printed image may differ depending on the amount of each spot color material used. In other words, the properties of the image may differ when a large amount of a first spot color (e.g., fluorescent pink) color material is used compared to when a large amount of a second spot color material (e.g., metallic color) color material is used.

[0060] When color conversion device 30 converts signal values ​​in an RGB color space representing image data into signal values ​​in a color space including multiple types of spot colors, it is preferable to separately set a first spot color conversion ratio, which is the ratio for converting to the signal value of the first spot color, and a second spot color conversion ratio, which is the ratio for converting to the signal value of the second spot color. For example, the color conversion device 30 allows the usage amount of the first spot color color material and the usage amount of the second spot color color material to be individually selected on a selection screen 90 (see FIG. 3) displayed on the operation display unit 35 (see FIG. 2).Then, the color conversion device 30 sets the first spot color conversion ratio and the second spot color conversion ratio individually based on the usage amount of the first spot color color material and the usage amount of the second spot color color material selected in response to an operation on the selection screen 90, and generates a color conversion profile. As a result, compared to generating a color conversion profile by uniformly setting the first spot color conversion ratio and the second spot color conversion ratio without distinguishing between them, the image printed by the printing device 20 is more likely to have properties that correspond to the amount of color material used for each spot color.

[0061] In the above embodiment, the profile generation unit 40 of the color conversion device 30 generates a color conversion profile that converts signal values ​​in the RGB color space into signal values ​​in the YMCKP color space that can be reproduced by the printing device 20, but this is not limited to the above. For example, the profile generation unit 40 of the color conversion device 30 may * a * b * A color conversion profile may be generated to convert the signal values ​​of the color space into signal values ​​of the YMCKP color space. In this case, the color conversion device 30 converts the signal values ​​of the RGB color space representing the image data input from the input device 10 into the L color space using another color conversion profile, etc. * a * b * After converting the signal values ​​into color space, the color conversion profile generated by the profile generating unit 40 is used to convert the L * a * b * The signal values ​​in the color space are converted into signal values ​​in the YMCKP color space.

[0062] Although the signal values ​​representing the image data input from the input device 10 to the color conversion device 30 are exemplified as signal values ​​in the RGB color space, the present invention is not limited to this. The signal values ​​representing the image data input from the input device 10 to the color conversion device 30 may be signal values ​​represented in a color space such as YMCK or YMCKRGB in addition to the RGB color space. In the color conversion device 30, the first conversion unit 41 of the profile generation unit 40 converts the signal values ​​in the RGB color space into the L color space, which is a device-independent color space. * a * b * Converts the signal value of the color space, but the device-independent color space is L * a * b * Not limited to color spaces. For example, XYZ color space, Yxy color space, L * u * v * It may be a color space, an HLS color space, etc.

[0063] Although the embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention.

[0064] The processor in the above-described embodiments refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPU (=Central Processing Unit)) as well as dedicated processors (e.g., GPU (=Graphical Processing Unit), ASIC (=Application Specific Integrated Circuit), FPGA (=Field Programmable Gate Array), programmable logic devices, etc.). In addition, the operations of the processor in this embodiment may be executed by one processor alone, or may be executed by multiple processors located at physically separate locations in cooperation with each other. Furthermore, the order of execution of each operation in the processor is not limited to the order described in the above embodiment, and may be changed individually.

[0065] <Additional Notes> (((1))) A processor is provided. The processor, When signal values ​​of a first color space representing an image are converted into signal values ​​of a second color space including a YMCK signal corresponding to the usage amount of color materials of YMCK colors and a spot color signal corresponding to the usage amount of a spot color color other than YMCK colors, a spot color conversion ratio, which is a ratio at which the signal values ​​of the first color space are converted into the spot color signals, is set according to the properties of an image printed using the signal values ​​of the second color space. Color conversion device. (((2))) The processor sets a K color conversion ratio, which is a ratio for converting signal values ​​of the first color space into K color signals, and the spot color conversion ratio in accordance with the properties of an image to be printed using signal values ​​of the second color space. (((3))) The processor sets the spot color conversion ratio and the K color conversion ratio in conjunction with each other depending on the characteristics of the image to be printed using the signal values ​​of the second color space. (((4))) The processor changes the spot color conversion ratio so that the usage amount of the spot color colorant is reduced below a predetermined reference value, and changes the K color conversion ratio so that the usage amount of the K color material is increased (((3))). (((5))) The color conversion device described in ((3))) or ((4))), wherein the processor does not change the K color conversion ratio when changing the spot color conversion ratio so that the usage amount of the spot color colorant increases above a predetermined reference value. (((6))) The color conversion device described in any of (((1))) to (((5))), wherein, when converting signal values ​​of the first color space into signal values ​​of the second color space including the YMCK signal and a plurality of spot color signals corresponding to the usage amounts of a plurality of spot color materials, the processor individually sets a plurality of spot color conversion ratios, which are ratios for converting the signal values ​​of the first color space into the respective spot color signals, in accordance with the properties of an image to be printed using the signal values ​​of the second color space. (((7))) The processor causes a display unit that displays information to display an image showing the correspondence between the amount of color material used of the spot color and the properties of an image printed using signal values ​​of the second color space. A color conversion device described in any of ((1))) to (((6))). (((8))) the processor acquires information regarding the usage amount of the spot color material in response to an operation on the displayed image; The color conversion device according to ((7))) sets the spot color conversion ratio based on the usage amount of the spot color color material. (((9))) the processor sets the usage amount of the K color material in conjunction with the usage amount of the spot color color material acquired in response to an operation on the display image, and then sets the usage amount of the spot color color material or the usage amount of the K color color material individually in response to the operation on the display image; setting the spot color conversion ratio based on the usage amount of the spot color color material; The color conversion device according to ((8))) sets a K color conversion ratio, which is a ratio at which a signal value in the first color space is converted into a K color signal, based on the usage amount of the K color material. (((10))) The processor sets the spot color conversion ratio to convert the signal value of the first color space representing a specific area that satisfies predetermined conditions in an image printed using the signal values ​​of the second color space into the spot color signal in accordance with the characteristics of the specific area. (((11))) A processor is provided. The processor creates a color conversion table that converts signal values ​​in a first color space representing an image into signal values ​​in a second color space including YMCK signals corresponding to the usage amounts of color materials of YMCK colors and spot color signals corresponding to the usage amounts of color materials of spot colors other than YMCK colors, and the spot color conversion ratio, which is the ratio at which the signal values ​​in the first color space are converted into the spot color signals, is determined according to the properties of an image to be printed using the signal values ​​in the second color space. Color conversion table creation device. (((12))) On the computer, A program that realizes a function of setting a spot color conversion ratio, which is the ratio at which the signal values ​​of the first color space representing an image are converted into spot color signals, in accordance with the properties of an image to be printed using the signal values ​​of the second color space, when converting signal values ​​of a first color space representing an image into signal values ​​of a second color space including a YMCK signal corresponding to the usage amount of color materials of the YMCK colors and a spot color signal corresponding to the usage amount of a spot color material that is a color other than YMCK.

[0066] The color conversion device according to (((1))) makes it easier for a user to obtain an image having the properties desired, compared to a case where a uniform conversion ratio is used to convert signal values ​​in a first color space into special color signals in signal values ​​in a second color space. According to the color conversion device of (((2))), it is easier for a user to obtain an image having the desired properties, compared to a case where a conversion ratio for converting a signal value in a first color space to a K color signal in a signal value in a second color space is uniform. According to the color conversion device of (((3))), an image having the characteristics desired by the user can be obtained with simpler operations than when the spot color conversion ratio and the K color conversion ratio are set without being linked. According to the color conversion device of (((4))), when the spot color conversion ratio is changed so that the amount of spot color material used is reduced below a reference value, it is easier to improve the light fastness of the image and the cost required to print the image, which are image properties, compared to when the K color conversion ratio is changed so that the amount of K color material used is reduced. According to the color conversion device of (((5))), when the spot color conversion ratio is changed so that the amount of spot color material used is increased above a reference value, it is easier to improve the graininess of the image as an image property, compared to when the K color conversion ratio is changed so that the amount of K color material used is increased. According to the color conversion device in accordance with (((6))), it is possible to more easily obtain an image having the properties desired by the user, compared to a case in which a plurality of spot color conversion ratios are set uniformly. According to the color conversion device of (((7))), the user can easily grasp the difference in the characteristics of the image caused by changing the amount of spot color material used, compared to a case in which the display unit does not display the correspondence between the amount of spot color material used and the characteristics of the image. According to the color conversion device of (((8))), the user can set the amount of spot color material to be used by manipulating the displayed image while checking on the display unit the correspondence between the amount of spot color material to be used and the properties of the image. According to the color conversion device of (((9))), it is easier for a user to obtain an image having the desired characteristics, compared to a case where information regarding the amount of spot color material used or the amount of K color material used is not obtained separately. According to the color conversion device of (((10))), it is possible to more easily obtain an image having the characteristics desired by the user, compared to a case in which the spot color conversion ratio for converting a signal value of a first color space representing a specific region into a spot color signal is not set according to the characteristics of the specific region. According to the color conversion table creation device of (((11))), it is possible to more easily obtain an image having the properties desired by the user, compared to a case where a conversion ratio for converting a signal value in a first color space into a spot color signal in a signal value in a second color space is uniform. According to the program pertaining to (((12))), it is possible to more easily obtain an image having the properties desired by the user, compared to a case where a conversion ratio for converting signal values ​​in a first color space into spot color signals in signal values ​​in a second color space is uniform. [Explanation of symbols]

[0067] 10...input device, 20...printing device, 21...printing unit, 22...printing control unit, 30...color conversion device, 31...color conversion unit, 33...profile storage unit, 35...operation display unit, 40...profile generation unit, 41...first conversion unit, 42...color gamut compression unit, 43...second conversion unit, 45...K color setting unit, 46...spot color setting unit, 90...selection screen, 91...toner amount selection unit, 92...property display unit, 93...property notification unit, 94...individual selection unit, 95...spot color toner amount selection unit, 96...K color toner amount selection unit, 97...area setting unit

Claims

1. A processor is provided. The processor, When signal values ​​of a first color space representing an image are converted into signal values ​​of a second color space including a YMCK signal corresponding to the usage amount of color materials of YMCK colors and a spot color signal corresponding to the usage amount of a spot color color other than YMCK colors, a spot color conversion ratio, which is a ratio at which the signal values ​​of the first color space are converted into the spot color signals, is set according to the properties of an image printed using the signal values ​​of the second color space. Color conversion device.

2. 2. The color conversion device according to claim 1, wherein the processor sets a K color conversion ratio, which is a ratio for converting signal values ​​of the first color space into K color signals, and the spot color conversion ratio in accordance with the properties of an image to be printed using signal values ​​of the second color space.

3. 3. The color conversion device according to claim 2, wherein the processor sets the spot color conversion ratio and the K color conversion ratio in conjunction with each other in accordance with the nature of an image to be printed using signal values ​​in the second color space.

4. The color conversion device according to claim 3 , wherein the processor changes the K color conversion ratio so that the usage amount of the K color material increases when the spot color conversion ratio is changed so that the usage amount of the spot color color material decreases below a predetermined reference value.

5. 5. The color conversion device according to claim 3, wherein the processor does not change the K color conversion ratio when the spot color conversion ratio is changed so that the usage amount of the spot color colorant increases above a predetermined reference value.

6. 2. The color conversion device according to claim 1, wherein when the processor converts the signal values ​​of the first color space into signal values ​​of the second color space including the YMCK signal and a plurality of spot color signals corresponding to the usage amounts of a plurality of spot color materials, the processor individually sets a plurality of spot color conversion ratios, which are ratios for converting the signal values ​​of the first color space into the respective spot color signals, in accordance with the properties of an image to be printed using the signal values ​​of the second color space.

7. The color conversion device according to claim 1 , wherein the processor causes a display unit that displays information to display an image showing the correspondence between the amount of color material used of the spot color and the properties of an image printed using signal values ​​of the second color space.

8. the processor acquires information regarding the usage amount of the spot color material in response to an operation on the displayed image; 8. The color conversion device according to claim 7, wherein the spot color conversion ratio is set based on the usage amount of the spot color color material.

9. the processor sets an amount of the K color material to be used in conjunction with an amount of the spot color material to be used that is acquired in response to an operation on the display image, and then sets an amount of the spot color color material to be used or an amount of the K color material to be used individually in response to the operation on the display image; setting the spot color conversion ratio based on the usage amount of the spot color color material; 9. The color conversion device according to claim 8, wherein a K color conversion ratio, which is a ratio at which a signal value in the first color space is converted into a K color signal, is set based on a usage amount of the K color material.

10. 2. The color conversion device according to claim 1, wherein the processor sets the spot color conversion ratio for converting the signal values ​​of the first color space representing a specific area that satisfies predetermined conditions in an image printed using the signal values ​​of the second color space into the spot color signal in accordance with the characteristics of the specific area.

11. A processor is provided. The processor creates a color conversion table that converts signal values ​​in a first color space representing an image into signal values ​​in a second color space including YMCK signals corresponding to the amounts of YMCK color materials used and spot color signals corresponding to the amounts of spot color materials used that are colors other than YMCK, and a spot color conversion ratio, which is a ratio for converting the signal values ​​in the first color space into the spot color signals, is determined according to the properties of an image to be printed using the signal values ​​in the second color space. Color conversion table creation device.

12. On the computer, A program that realizes a function of setting a spot color conversion ratio, which is the ratio at which the signal values ​​of the first color space representing an image are converted into the spot color signals, in accordance with the properties of an image to be printed using the signal values ​​of the second color space, when converting signal values ​​of a first color space representing an image into signal values ​​of a second color space including a YMCK signal corresponding to the usage amount of color materials of the YMCK colors and a spot color signal corresponding to the usage amount of a spot color material that is a color other than YMCK.

Images