Method for creating proof image data, proof image data creation apparatus, and computer program

Abstract

This technology provides the ability to generate proof image data that reproduces the print observed when using a backing of any color on a sheer printed fabric. [Solution] The disclosed method includes (a) acquiring basic proof image data for reproducing the color of a basic printed material with a basic backing applied to a translucent printed fabric; (b) acquiring texture information of the translucent fabric; (c) acquiring a basic backing color and an observation backing color; (d) creating foreground proof image data by removing the basic backing color from the basic proof image data; and (e) creating observation proof image data by combining the observation backing color with the foreground proof image data. Step (e) includes (e1) determining the observation color mixing ratio which changes depending on the brightness of the basic proof image data; and (e2) creating observation proof image data according to the observation color mixing ratio.

Description

Technical Field

[0001] The present disclosure relates to a method for creating proof image data, a proof image data creation device, and a computer program.

Background Art

[0002] Patent Document 1 discloses a method for creating a proof image for calibrating a printed matter. In this prior art, a proof image is created by correcting an image based on the density distribution on the two-dimensional space of the surface of a printed matter printed at 100% density on a printing medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a printed fabric with an image printed on a sheer fabric, the apparent color of the printed fabric changes significantly depending on the color of the backing (lining material). However, conventionally, there has been no known technique for creating a proof image considering the color of the backing for a sheer printed fabric. Therefore, a technique capable of generating proof image data that reproduces a printed matter observed when using a backing of an arbitrary color for a sheer printed fabric is desired.

Means for Solving the Problems

[0005] A first embodiment of this disclosure provides a method for creating proof image data. This method includes: (a) acquiring basic proof image data for reproducing the color of a basic printed material, which is a transparent printed fabric with a basic backing applied to a transparent fabric printed with an image using a printing press, using a proof output device; (b) acquiring texture information of the transparent fabric; (c) acquiring a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of an observation backing used in the observation environment of the transparent printed fabric; (d) creating foreground proof image data representing the color of the transparent printed fabric as observed without the backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information; and (e) creating observation proof image data representing the color of an observation printed material, which is a transparent printed fabric with the observation backing applied by performing a synthesis process to synthesize the observation backing color with the color represented by the foreground proof image data according to the texture information. The step (e) includes (e1) determining the observed color mixing ratio of the observed backing color, assuming that the color of the observation print is a mixture of the color of the translucent print fabric and the observation backing color, according to the texture information and the basic proof image data; and (e2) creating the observation proof image data by performing an operation to combine the basic backing color with the color represented by the foreground proof image data according to the observed color mixing ratio. The observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

[0006] A proof image data creation device is provided according to a second embodiment of the present disclosure. This proof image data creation device includes: a basic proof image acquisition unit that acquires basic proof image data for reproducing the color of a basic printed material, which is obtained by applying a basic backing to a transparent printed fabric on which an image has been printed using a printing press, using a proof output device; a texture information acquisition unit that acquires texture information of the transparent fabric; a backing color information acquisition unit that acquires a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric; a color correction unit that creates foreground proof image data representing the color of the transparent printed fabric as observed without the backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information; and a synthesis unit that creates observation proof image data representing the color of an observation printed material, which is obtained by applying the observation backing to the transparent printed fabric by performing a synthesis process to synthesize the observation backing color with the color represented by the foreground proof image data according to the texture information. The synthesis unit is configured to perform the following: (e1) a process of determining the observed color mixing ratio of the observed backing color, assuming that the color of the observation print is a mixture of the color of the translucent print fabric and the observation backing color, according to the texture information and the basic proof image data; and (e2) a process of creating the observation proof image data by performing an operation to synthesize the basic backing color with the color represented by the foreground color proof image data according to the observed color mixing ratio. The observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

[0007] A third embodiment of this disclosure provides a computer program for creating proof image data. This computer program causes a computer to perform the following: (a) a process of acquiring basic proof image data for reproducing the color of a basic printed material, which is a transparent printed fabric with an image printed on it using a printing press and to which a basic backing has been applied, using a proof output device; (b) a process of acquiring texture information of the transparent fabric; (c) a process of acquiring a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric; (d) a process of creating foreground proof image data representing the color of the transparent printed fabric as observed without the backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information; and (e) a process of creating observation proof image data representing the color of an observation printed material, which is a transparent printed fabric with the observation backing applied, by performing a synthesis process to synthesize the observation backing color with the color represented by the foreground proof image data according to the texture information. The process (e) includes (e1) determining the observed color mixing ratio of the observed backing color, assuming that the color of the observation print is a mixture of the color of the translucent print fabric and the observation backing color, according to the texture information and the basic proof image data; and (e2) creating the observation proof image data by performing an operation to combine the basic backing color with the color represented by the foreground color proof image data according to the observed color mixing ratio. The observed color mixing ratio is set to change depending on the brightness of the basic proof image data. [Brief explanation of the drawing]

[0008] [Figure 1] An explanatory diagram showing a printing system for proofreading printed materials. [Figure 2] A block diagram showing the configuration of a proof image data creation device. [Figure 3] An explanatory diagram showing the flow of the proof image creation process. [Figure 4] An explanatory diagram showing examples of translucent printed fabrics with different backings. [Figure 5] An explanatory diagram showing how the appearance of the backing differs depending on the brightness of the translucent printed fabric. [Figure 6] An explanatory diagram comparing the way light is transmitted in a reference example and an embodiment. [Figure 7] A flowchart illustrating the procedure for creating proof image data. [Figure 8] An explanatory diagram showing an example of texture values. [Figure 9] An explanatory diagram showing an example of a window used to acquire transparency characteristic information. [Figure 10] An explanatory diagram showing an example of a window used to obtain backing color information. [Figure 11] A flowchart showing the detailed steps for step S40. [Figure 12] A graph showing an example of a background reference rate determination curve. [Figure 13] A graph showing an example of an adjustment coefficient determination curve. [Figure 14] A graph showing an example of the result of multiplying the pixel background reference ratio by an adjustment factor. [Figure 15] An explanatory diagram showing the flow of the proof image creation process in the second embodiment. [Modes for carrying out the invention]

[0009] A. First Embodiment: Figure 1 is an explanatory diagram showing a printing system 500 for proofreading printed materials. This printing system 500 comprises a printing press 100 that prints printed materials PM according to input image data IM, a proof image data creation device 200 that creates proof image data using the input image data IM, and a proofing printing device 300 that prints proofs according to the proof image data.

[0010] Proofing includes hard proofing, which involves printing a proof printout HP using a proofing printer 300, and soft proofing, which displays a proof image SP on a display device 205 according to the proof image data. In hard proofing, the proofing printer 300 corresponds to the "proof output device," and in soft proofing, the display device 205 corresponds to the "proof output device." The image output from the proof output device is also called the "output image." In hard proofing, the proof printout HP corresponds to the "output image," and in soft proofing, the proof image SP corresponds to the "output image."

[0011] The printing press 100 is a textile printing press that creates printed fabric by performing textile printing on a printing medium, such as a cloth. In this embodiment, a sheer fabric is used as the printing medium. Examples of sheer fabrics that can be used include woven fabrics such as chiffon, tulle, organza, georgette, lace, mesh, lawn, and gauze. A sheer fabric is called a "transparent fabric." A transparent fabric on which an image has been printed is called a "transparent printed fabric."

[0012] The proof image data creation device 200 is configured to perform at least one of hard proofing and soft proofing. In hard proofing, the proofing printer 300 prints a proof print HP according to the proof image data created by the proof image data creation device 200. If the proofing printer 300 is an inkjet printer, the proof image data creation device 200 applies color conversion processing and halftone processing to the proof image data to create dot data for printing, and supplies this dot data to the proofing printer 300 to print a proof print HP. In soft proofing, a proof image SP is displayed on the display device 205 according to the proof image data created by the proof image data creation device 200. This disclosure is applicable to both hard proofing and soft proofing.

[0013] FIG. 2 is a block diagram showing the configuration of the proof image data creation apparatus 200. The proof image data creation apparatus 200 is a computer including a CPU 201, a storage unit 202, an input / output interface 203, and a display device 205. The CPU 201, the storage unit 202, and the input / output interface 203 are connected so as to be able to communicate bidirectionally via an internal bus.

[0014] The CPU 201 functions as a basic proof image acquisition unit 210, a texture information acquisition unit 220, a backing color information acquisition unit 230, a color correction unit 240, and a composition unit 250 by executing a proof image creation program PG stored in advance in the storage unit 202. At least a part of the functions of these units 210 to 250 may be realized by a hardware circuit, or may be realized on the cloud.

[0015] The input / output interface 203 is connected to the display device 205 and the calibration printing apparatus 300 by wire or wirelessly. The display device 205 is used to display a window and a proof image, which will be described later.

[0016] FIG. 3 is an explanatory diagram showing the flow of the proof image creation process. The basic proof image acquisition unit 210 acquires basic proof image data BPF. The basic proof image data BPF is data that reflects the difference in color reproduction between the printing machine 100 and the proof output device in the input image data IM. In the present embodiment, the basic proof image data BPF is data for reproducing the color of a basic printed matter obtained by applying basic backing to a transparent printed fabric printed by the printing machine 100 using the proof output device.

[0017] "Backing" refers to the backing material for printed fabrics. In a typical example, basic backing is used when creating a media profile for a printing press 100 on a translucent fabric. Specifically, first, multiple color patches are printed on the translucent fabric using the printing press 100. Then, color measurements are taken with the translucent fabric with the color patches printed on it and the basic backing applied, and the media profile is created using the color measurement results. The basic backing may also be called "color measurement backing."

[0018] This disclosure uses a translucent fabric in which the appearance of the backing differs depending on the brightness of the translucent printed fabric. For example, with cotton-linen lawn, the backing is less visible in black printed areas and more visible in white printed areas. The characteristics of such translucent fabrics will be described later.

[0019] In this embodiment, the basic proof image acquisition unit 210 creates basic proof image data BPF from the input image data IM. This creation process uses, for example, the input profile of the input image data IM, the device profile and media profile of the proof output device, and various ICC profiles IPF such as the media profile of the printing press 100. However, if the basic proof image data BPF has already been created, the basic proof image acquisition unit 210 may acquire it by reading the basic proof image data BPF from the storage unit 202.

[0020] Any method can be used to create the basic proof image data (BPF). For example, the method described in Japanese Patent Publication No. 2024-81234, disclosed by the applicant of this disclosure, may be used. In this method, the following processes are executed sequentially. <Processing P1> The first image data is obtained by converting the color space of the input image data IM to the output color space of the printer 100 using the ICC profile IPF. <Processing P2> The first image data is transformed using a first transformation table to represent it in the profile connection space, and a white point transformation is performed on the background color area where no image is formed in the printed PM, using information on how it appears in a predetermined observation environment. This process yields the second image data, which is represented in the absolute XYZ color space. <Processing P3> Using the second conversion table, the second image data is converted into converted image data represented in the output color space of the proof output device. The output color space of the proof output device is, for example, the CMYK color space or the RGB color space.

[0021] Alternatively, proof images may be created using the methods described in the above-mentioned prior art (Japanese Patent Publication No. 09-270930) or Japanese Patent Publication No. 2006-30277. When using the method of Japanese Patent Publication No. 09-270930, a basic proof image data (BPF) that does not reflect the texture can be created by omitting the first and second corrections related to the texture of the paper.

[0022] In the first embodiment, the basic proof image data BPF is assumed to be represented in the L*a*b* color space. However, it may also be represented in other device-independent color spaces such as the XYZ color space. When basic proof image data is created in the output color space of the proof output device using the various methods described above, the output color space can be converted to the L*a*b* color space using the output profile of the proof output device. Furthermore, when using the method described in Japanese Patent Application Publication No. 2024-81234, the basic proof image data BPF may be created by converting the second image data, which is represented in the absolute XYZ color space, to the L*a*b* color space. In the following description, L*a*b* will simply be referred to as "Lab".

[0023] Figure 4 is an explanatory diagram showing examples of translucent printed fabrics with different backings. On the left side of Figure 4, a basic print (PM_basic) is shown with a basic backing (Back_basic) applied to a translucent printed fabric (TPF) without a backing. The color of the basic backing (Back_basic) is, for example, white. On the right side of Figure 4, an observation print (PM_obs) is shown with an observation backing (Back_obs) applied to a translucent printed fabric (TPF) without a backing. The color of the observation backing (Back_obs) is, for example, black. In this embodiment, it is possible not only to create a proof of the basic print (PM_basic) with the basic backing (Back_basic), but also to create a proof of the observation print (PM_obs) with an observation backing (Back_obs) of any color. The basic proof image data (BPF) is data representing the color of the basic print (PM_basic).

[0024] Figure 5 is an explanatory diagram illustrating the difference in the appearance of backing depending on the brightness of translucent printed fabric. The left side of Figure 5 shows printed material PM_high-L, which is made by applying a black backing Back_black to a high-brightness translucent printed fabric TPF_high-L, and the right side of Figure 5 shows printed material PM_low-L, which is made by applying a white backing Back_white to a low-brightness translucent printed fabric TPF_low-L. Both of these are examples using cotton-linen lawn as the translucent fabric. In the high-brightness printed material PM_high-L, the color of the black backing Back_black is visible, and the brightness is lower than that of the translucent printed fabric TPF_high-L. On the other hand, in the low-brightness printed material PM_low-L, the color of the white backing Back_white is not visible, and the brightness is almost the same as that of the translucent printed fabric TPF_low-L. It is presumed that this difference in the appearance of the backing is due to the different ways in which light is transmitted in translucent fabrics.

[0025] Figure 6 is an explanatory diagram comparing the way light is transmitted in the reference example and the embodiment. In the reference example's transparent fabric TF1, the size of the gaps between the threads in the knit is larger than in the embodiment's transparent fabric TF2. In the reference example's transparent fabric TF1, because the gaps between the knit are large, the amount of light that reaches the backing and the amount of light that returns from the backing are ensured regardless of the brightness of the transparent printed fabric. As a result, the color of the backing can be confirmed regardless of the brightness of the transparent printed fabric.

[0026] On the other hand, the transparent fabric TF2 of the embodiment has a smaller gap size between the yarns in the knit than the transparent fabric TF1 of the reference example. In the transparent printed fabric created with the transparent fabric TF2 of the embodiment, in the high-brightness region shown on the left, a certain amount of light reaches the backing, but absorption by the black backing (Back_black) reduces the amount of light, making it appear less bright. On the other hand, in the low-brightness region shown on the right, light is absorbed by the printed material, reducing the amount of light that reaches the backing, and further light returning from the backing is also absorbed, reducing it even more. As a result, the color of the white backing (Back_white) is almost invisible. The difference in the appearance of the backing with respect to the transparent fabric TF2 of the embodiment corresponds to the difference in appearance between the left and right examples in Figure 5 described above. This disclosure assumes the use of a transparent fabric TF2 having such characteristics. As will be described later, the color correction unit 240 and the synthesis unit 250 perform their respective processes considering that the appearance of the backing color differs depending on the brightness of the transparent printed fabric.

[0027] The color correction unit 240 shown in Figure 3 creates foreground color proof image data FPF by performing a color correction process that removes the basic backing color BBC from the color represented by the basic proof image data BPF according to the texture information TI. The foreground color proof image data FPF is data that represents the color of the translucent printed fabric TPF as observed without backing. In this embodiment, the foreground color proof image data FPF is represented in the Lab color space.

[0028] The synthesis unit 250 creates observation proof image data OPF by performing a synthesis process that combines the observation backing color OBC with the color represented by the foreground proof image data FPF according to the texture information TI. The observation proof image data OPF is data representing the color of the observation print PM_obs as described in Figure 4. In this embodiment, the observation proof image data OPF is represented in the Lab color space.

[0029] Figure 7 is a flowchart showing the procedure for creating proof image data. In step S10, the basic proof image acquisition unit 210 acquires basic proof image data BPF. In step S20, the texture information acquisition unit 220 acquires texture information TI of the translucent fabric. In this embodiment, the texture information TI includes the texture value for each pixel and transparency characteristic information.

[0030] Figure 8 is an explanatory diagram showing an example of texture value Dtx as texture information TI. As texture value Dtx, a brightness value map generated from image data of a printed medium, or a Height Map used in 3D rendering, can be used. In either case, it is preferable that texture value Dtx is configured as a map of values ​​indicating the brightness or unevenness of the printed medium. In the example in Figure 8, texture value Dtx is in the range of 0 (black) to 100 (white). It is preferable that the image area of ​​texture value Dtx has the same size as the image area of ​​the basic proof image data BPF. Texture value Dtx can be acquired, for example, using the texture information acquisition device described in Japanese Patent Application No. 2024-116006 disclosed by the applicant of this disclosure.

[0031] Figure 9 is an explanatory diagram showing an example of window W1 used to acquire transparency characteristic information as texture information TI. This window W1 is provided with five input fields IF11 to IF15 for inputting the following five setting values ​​that constitute the transparency characteristic information.

[0032] (A) Thread texture threshold Th_thread The thread texture threshold Th_thread is the minimum texture value Dtx required to determine that each pixel is on a thread in a translucent fabric. That is, pixels whose texture value Dtx is greater than or equal to the thread texture threshold Th_thread are determined to be on a thread. The thread texture threshold Th_thread is set to a value greater than 0 and less than or equal to 100. In Figure 8 mentioned above, pixels that are determined to be on a thread when Th_thread=100 are shown as white areas without hatching.

[0033] (B) Gap texture threshold Th_hole The gap texture threshold Th_hole is the maximum value of the texture value Dtx used to determine that each pixel corresponds to a gap in the weave of a translucent fabric. That is, pixels whose texture value Dtx is less than or equal to the gap texture threshold Th_hole are determined to correspond to a gap in the weave. The gap texture threshold Th_hole is set to a value between 0 and 100, for example. Also, the gap texture threshold Th_hole is set to a smaller value (darker value) than the thread texture threshold Th_thread. In the example in Figure 8 mentioned above, when Th_hole=50, pixels determined to correspond to gaps in the weave are shown as dark gray areas. Pixels with intermediate brightness between threads and gaps are shown as light gray areas.

[0034] (C) Thread background reference rate Rb_thread The thread background reference ratio Rb_thread is the percentage of pixels corresponding to the weaving thread that reference the backing color. The backing color referenced can be either the basic backing color or the observed backing color. The thread background reference ratio Rb_thread is set to a value between 0 and 1.0, for example.

[0035] (D) Gap background reference rate Rb_hole The gap background reference ratio Rb_hole is the percentage of pixels corresponding to gaps that reference the backing color. The gap background reference ratio Rb_hole is set to a value between 0 and 1.0, for example. Also, the gap background reference ratio Rb_hole is set to a value greater than the thread background reference ratio Rb_thread.

[0036] (E) Background reference ratio correction coefficient for black areas K_set The background reference rate correction coefficient K_set for black regions is a setting value for an adjustment coefficient used to adjust the background reference rate of pixels in black regions. For example, the background reference rate correction coefficient K_set is set to a value greater than 0 and less than or equal to 1.0.

[0037] Alternatively, instead of the user inputting the thread-on-thread background reference ratio Rb_thread and the gap-background reference ratio Rb_hole, these values ​​may be set using transparency values ​​obtained from captured images using a white background and a black background, as described in Japanese Patent Publication No. 2005-251162. For example, the minimum transparency of the fabric may be set as the thread-on-thread background reference ratio Rb_thread, and the maximum transparency of the fabric may be set as the gap-background reference ratio Rb_hole.

[0038] The transparency characteristics information set in Figure 9 is used in the color correction process performed by the color correction unit 240 and the synthesis process performed by the synthesis unit 250. The details of the color correction process and the synthesis process will be described later.

[0039] In step S30 of Figure 7, the backing color information acquisition unit 230 acquires backing color information including the basic backing color BBC and the observed backing color OBC.

[0040] Figure 10 is an explanatory diagram showing an example of a window W2 used to acquire backing color information. This window W2 is provided with an input field IF21 for inputting the basic backing color BBC and an input field IF22 for inputting the observed backing color OBC. In this embodiment, the basic backing color BBC and the observed backing color OBC are set using Lab values, respectively. In the example in Figure 10, the basic backing color BBC is white and the observed backing color OBC is black.

[0041] Furthermore, the basic backing color BBC and the observed backing color OBC may be acquired as images. That is, the backing color information acquisition unit 230 may acquire a Lab image of the observed backing color OBC specified by the user.

[0042] In step S40 of Figure 7, the color correction unit 240 determines the basic color mixing ratio according to the brightness of the texture information TI and the basic proof image data BPF. The basic color mixing ratio is the mixing ratio of the basic backing color BBC when the color of the basic printed material PM_basic, as explained in Figure 4, is considered to be a mixture of the color of the translucent printed fabric TPF and the basic backing color BBC. In other words, the basic color mixing ratio is the mixing ratio of the basic backing color BBC when the color represented by the basic proof image data BPF is considered to be a mixture of the color represented by the foreground proof image data FPF and the basic backing color BBC.

[0043] If the basic color mixing ratio is Rmix_basic, the color mixing for the basic proof image data BPF is expressed by the following formula. Lab_basic = Lab_fore×(1 - Rmix_basic) + Lab_b.back×Rmix_basic …(q1) Here, Lab_basic is the Lab value of the basic proof image data BPF. Lab_fore is the Lab value of the foreground proof image data FPF. Lab_b.back is the Lab value of the basic backing color BBC. The basic mixing ratio Rmix_basic is a value greater than 0 and less than 1.0.

[0044] FIG. 11 is a flowchart showing the detailed procedure of step S40. In step S41, the color correction unit 240 determines the pixel background reference rate Rb_px, which is the background reference rate of each pixel, according to the texture value Dtx, using the background reference rate determination curve determined by the transmission characteristic information.

[0045] FIG. 12 is a graph showing an example of the background reference rate determination curve Gr. The background reference rate determination curve Gr preferably shows the characteristic that the pixel background reference rate Rb_px becomes smaller as the lightness represented by the texture value Dtx is larger. The pixel background reference rate Rb_px is determined as follows according to the texture value Dtx of each pixel. (a1) Pixels where the texture value Dtx is less than or equal to the gap texture threshold Th_hole: The pixel background reference rate Rb_px is set to a value equal to the gap background reference rate Rb_hole. (a2) Pixels where Th_hole < Dtx < Th_thread: The pixel background reference rate Rb_px is determined by linearly interpolating between the on-thread background reference rate Rb_thread and the gap background reference rate Rb_hole according to the texture value Dtx. (a3) Pixels where the texture value Dtx is greater than or equal to the on-thread texture threshold Th_thread: The pixel background reference rate Rb_px is set to a value equal to the on-thread background reference rate Rb_thread.

[0046] Instead of inputting the set value of the transmission characteristic information shown in FIG. 9, an image of the pixel background reference rate Rb_px may be acquired as the transmission characteristic information. That is, the texture information acquisition unit 220 may acquire a map of the pixel background reference rate Rb_px specified by the user. In this case, it is preferable that the map of the pixel background reference rate Rb_px has the same image area as the image area of the basic proof image data BPF.

[0047] In step S42, the color correction unit 240 calculates the average background reference rate Rb_ave by averaging the pixel background reference rate Rb_px within the image area of the basic proof image data BPF.

[0048] In step S43, the color correction unit 240 determines an adjustment coefficient K_corr of the background reference rate according to the brightness of the basic proof image data BPF. The adjustment coefficient K_corr is determined to change depending on the brightness of the basic proof image data BPF using an adjustment coefficient determination curve determined by the transmission characteristic information.

[0049] FIG. 13 is a graph showing an example of the adjustment coefficient determination curve Gk. The adjustment coefficient K_corr is determined as follows according to the background reference rate correction coefficient K_set of the black area included in the transmission characteristic information shown in FIG. 9 and the white point Pwhite and black point Pblack included in the media profile of the see-through fabric. (b1) Pixels where the brightness L of the basic proof image data BPF is less than or equal to the black point Pblack: The adjustment coefficient K_corr is set to a value equal to the background reference rate correction coefficient K_set. (b2) Pixels where Pblack < L < Pwhite: The adjustment coefficient K_corr is determined by linearly interpolating between the background reference rate correction coefficient K_set and 1.0 according to the brightness L. (b3) Pixels where the brightness L of the basic proof image data BPF is greater than or equal to the white point Pwhite: The adjustment coefficient K_corr is set to 1.0.

[0050] In step S44, the color correction unit 240 determines the basic mixing ratio Rmix_basic using a value obtained by multiplying the average background reference rate Rb_ave or the pixel background reference rate Rb_px by the adjustment coefficient K_corr. For example, the basic mixing ratio Rmix_basic is calculated by any of the following equations. Rmix_basic = K_corr × Rb_ave …(q2-1) Rmix_basic = K_corr × Rb_px …(q2-2)

[0051] Figure 14 is a graph showing an example of the basic color mixing ratio Rmix_basic obtained by multiplying the pixel background reference ratio Rb_px by the adjustment coefficient K_corr. These graphs are the result of multiplying the background reference ratio determination curve Gr shown in Figure 12 by the adjustment coefficient K_corr when the brightness L is L=95, L=40, and L=10. As can be seen from Figure 14, the basic color mixing ratio Rmix_basic is set to become smaller as the brightness L of the basic proof image data BPF decreases.

[0052] It is preferable to determine the basic color mixing ratio Rmix_basic using the average background reference rate Rb_ave rather than the pixel background reference rate Rb_px. This is because if the basic color mixing ratio Rmix_basic is determined using the pixel background reference rate Rb_px, the amount of correction in the color correction process in step S50 may become excessive in the gaps between fibers, potentially preventing the correct determination of the color of the foreground color proof image data FPF. Actual translucent printed fabrics have a juxtaposition of colors between the gaps and the threads, and when observed from a distance, they appear as an average color. Therefore, in the color correction process, it is preferable to generate the foreground color proof image data FPF that more accurately represents the color of the translucent printed fabric as actually observed by removing the basic backing color using the average background reference rate Rb_ave.

[0053] Instead of equations (q2-1) and (q2-2) above, the following equation may be used to determine the basic color mixing ratio Rmix_basic. Rmix_basic = ave( K_corr×Rb_ave ) …(q2-3) Rmix_basic = ave( K_corr×Rb_px ) …(q2-4) Here, ave() is the operation for taking the average. Equations (q2-3) and (q2-4) use the average value of the pixel background reference ratio Rb_px to determine the basic color mixing ratio Rmix_basic, thus having the same advantages as (q2-1) above.

[0054] In step S50 of Figure 7, the color correction unit 240 performs a color correction process to remove the basic backing color BBC from the color represented by the basic proof image data BPF according to the basic color mixing ratio Rmix_basic, thereby creating the foreground color proof image data FPF. As mentioned above, the foreground color proof image data FPF is data that represents the color of the translucent printed fabric TPF as observed without backing.

[0055] The calculation in step S50 is performed, for example, according to the following formula: Lab_fore = (Lab_basic - Lab_b.back×Rmix_basic) / (1 - Rmix_basic) …(q3) Here, Lab_fore is the Lab value of the foreground proof image data FPF. Lab_basic is the Lab value of the basic proof image data BPF. Lab_b.back is the Lab value of the basic backing color BBC. Rmix_basic is the basic color mixing ratio. The calculation using equation (q3) is performed on the L, a, and b values ​​of the basic proof image data BPF, respectively. Equation (q3) is equivalent to a modified version of equation (q1) described above.

[0056] Instead of using equation (q3) above, the foreground color proof image data FPF may be calculated using the following equation. Lab_fore = (Lab_basic - α×Lab_b.back×Rmix_basic) / (1 - Rmix_basic) …(q4) Here, α is any non-zero positive coefficient. The coefficient α is used to adjust the strength of the influence of the basic backing colors BBC. It is preferable to use a value close to 1 for coefficient α. When α=1, equation (q4) becomes the same as equation (q3), so equation (q4) is a broader equation that encompasses equation (q3).

[0057] In step S60 of Figure 7, the color correction unit 240 determines the observed color mixing ratio according to the brightness of the texture information TI and the basic proof image data BPF. The observed color mixing ratio is the ratio of color mixing when the color of the observation print PM_obs, as explained in Figure 4, is considered to be a mixture of the color of the translucent print fabric TPF and the observation backing color OBC. In other words, the observed color mixing ratio is the ratio of color mixing when the color represented by the observation proof image data OPF is considered to be a mixture of the color represented by the foreground proof image data FPF and the observation backing color OBC.

[0058] In this embodiment, the average background reference rate Rb_ave or the pixel background reference rate Rb_px multiplied by the adjustment coefficient K_corr is used as the observed color mixing ratio Rmix_obs. That is, the observed color mixing ratio Rmix_obs is calculated using one of the following formulas. Rmix_obs = K_corr×Rb_ave …(q5-1) Rmix_obs = K_corr×Rb_px …(q5-2) The blending unit 250 can be considered to be performing the same process as steps S41 to S44 shown in Figure 11 as the process for determining the observed color mixing ratio Rmix_obs. The observed color mixing ratio Rmix_obs is set to change according to the brightness L of the basic proof image data BPF, just like the basic color mixing ratio Rmix_basic. Specifically, the observed color mixing ratio Rmix_obs is set to become smaller as the brightness L of the basic proof image data BPF decreases.

[0059] The observed color mixing ratio Rmix_obs may be the same as or different from the basic color mixing ratio Rmix_basic described above. However, it is preferable to use the value obtained by multiplying the average background reference rate Rb_ave by the adjustment coefficient K_corr as the basic color mixing ratio Rmix_basic, and the value obtained by multiplying the pixel background reference rate Rb_px by the adjustment coefficient K_corr as the observed color mixing ratio Rmix_obs. By using the value obtained by multiplying the pixel background reference rate Rb_px by the adjustment coefficient K_corr as the observed color mixing ratio Rmix_obs, the difference between the background and foreground colors in the thread areas and gap areas becomes clearer, so the texture of the translucent fabric can be reproduced more appropriately.

[0060] In step S70 of Figure 7, the synthesis unit 250 creates observation proof image data OPF by performing a synthesis process that combines the observation backing color OBC with the color represented by the foreground proof image data FPF according to the observation color mixing ratio Rmix_obs. This observation proof image data OPF is data that represents the color of the observation print PM_obs explained in Figure 4.

[0061] The synthesis process is performed according to, for example, the following equation. Lab_obs = Lab_fore×(1 - Rmix_obs) + Lab_o.back×Rmix_obs …(q6) Here, Lab_obs is the Lab value of the observation proof image data OPF. Lab_fore is the Lab value of the foreground proof image data FPF. Lab_o.back is the Lab value of the observed backing color OBC. Rmix_obs represents the observed color mixing ratio.

[0062] By using the observation proof image data OPF generated in this way, it is possible to reproduce the observation print PM_obs of the translucent printed fabric TPF, which is observed when any observation backing Back_obs is used, as a proof.

[0063] In the first embodiment described above, the basic backing color BBC is removed from the color represented by the basic proof image data BPF to generate the foreground color proof image data FPF, and then the observation backing color OBC is combined with the color represented by the foreground color proof image data FPF. As a result, a proof can be created that takes into account the observation backing color OBC, which is visible when the fabric is transparent under the observation environment of a translucent printed fabric. In addition, since the observation color mixing ratio Rmix_obs is set to change depending on the brightness of the basic proof image data BPF, the appearance of the observation backing color OBC can be changed according to the brightness of the basic proof image data BPF.

[0064] B. Second Embodiment: Figure 15 is an explanatory diagram showing the flow of the proof image creation process in the second embodiment. The main differences from the first embodiment shown in Figure 3 are the following two points. (1) The basic proof image data BPF is expressed in the RGB color space or CMYK color space, which is the output color space of the proof output device. (2) The color correction unit 240 includes a profile correction unit 241 and a color management module 242.

[0065] The profile correction unit 241 generates a color correction media profile CMP for translucent fabric without using the basic backing Back_basic by performing a profile conversion on the media profile MP of the printing press 100 for translucent fabric, using the basic backing color BBC and the basic color mixing ratio Rmix_basic which is determined according to the texture information TI and the basic proof image data BPF. This profile conversion is a process that changes the Lab value in the A2B table of the media profile MP. The A2B table is a table for converting the CMYK color space to the Lab color space.

[0066] The profile conversion operation removes the basic backing color BBC from the color represented by the device-independent color space data in the media profile MP according to the basic color mixing ratio Rmix_basic, and is performed using the following equation, similar to equation (q4) described above. Lab_corrected = (Lab_org - α×Lab_b.back×Rmix_basic) / (1 - Rmix_basic) …(q7) Here, Lab_corrected is the Lab value of the device-independent color space data after profile conversion. Lab_org is the Lab value of the device-independent color space data before profile conversion. Lab_b.back is the Lab value of the basic backing color BBC. Rmix_basic is the basic color mixing ratio. α is any non-zero positive coefficient. It is preferable to use a value determined according to the above formula (q2-3) or (q2-4) as the basic color mixing ratio Rmix_basic.

[0067] The color management module 242 creates foreground color proof image data (FPF) by performing a color management process that converts the base proof image data (BPF) to a device-independent color space using the color correction media profile (CMP). Specifically, it uses the A2B table of the color correction media profile (CMP) to convert the color space of the base proof image data (BPF) from the output color space CMYK of the proof output device to the device-independent color space Lab. This color conversion generates foreground color proof image data (FPF) represented in the device-independent color space Lab.

[0068] Other processes in the second embodiment are the same as in the first embodiment, so their description will be omitted. This second embodiment also produces almost the same effects as the first embodiment described above.

[0069] Other forms: This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, this disclosure can also be implemented in the following forms. The technical features in the embodiments described below that correspond to the technical features in each of the forms described below can be replaced or combined as appropriate in order to solve some or all of the problems of this disclosure, or to achieve some or all of the effects of this disclosure. Furthermore, if such technical features are not described as essential in this specification, they can be deleted as appropriate.

[0070] (1) According to a first embodiment of the present disclosure, a method for creating proof image data is provided. This method includes: (a) acquiring basic proof image data for reproducing the color of a basic printed material, which is a transparent printed fabric with an image printed on a transparent fabric using a printing press and to which a basic backing has been applied, using a proof output device; (b) acquiring texture information of the transparent fabric; (c) acquiring a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of an observation backing used in the observation environment of the transparent printed fabric; (d) creating foreground proof image data representing the color of the transparent printed fabric as observed without the backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information; and (e) creating observation proof image data representing the color of an observation printed material, which is a transparent printed fabric with the observation backing applied, by performing a synthesis process to synthesize the observation backing color with the color represented by the foreground proof image data according to the texture information. The step (e) includes (e1) determining the observed color mixing ratio of the observed backing color, assuming that the color of the observation print is a mixture of the color of the translucent print fabric and the observation backing color, according to the texture information and the basic proof image data; and (e2) creating the observation proof image data by performing an operation to combine the basic backing color with the color represented by the foreground proof image data according to the observed color mixing ratio. The observed color mixing ratio is set to change depending on the brightness of the basic proof image data. This method allows for the creation of proofs that take into account the observation backing color, which becomes visible when the fabric is transparent under the observation environment of a translucent printed fabric. Furthermore, the appearance of the observation backing color can be changed according to the brightness of the basic proof image data.

[0071] (2) In the above method, the observed color mixing ratio may be set such that the observed color mixing ratio becomes smaller as the brightness of the basic proof image data decreases. According to this method, by setting a smaller observation color mixing ratio as the brightness of the basic proof image data decreases, it is possible to reproduce a state where the backing color is difficult to see.

[0072] (3) In the above method, the texture information may include the transparency characteristics information of the transparent fabric and the texture value for each pixel. Step (e1) may include (e1-1) a step of determining the pixel background reference rate, which is the ratio to which the backing color is referenced in each pixel, according to the texture value using the transparency characteristics information, and (e1-2) a step of determining the observed color mixing ratio by multiplying the pixel background reference rate by an adjustment coefficient that changes depending on the brightness of the basic proof image data. This method allows us to determine the observed color mixing ratio, which changes depending on the brightness, using the texture values ​​and transparency characteristics of the texture information.

[0073] (4) In the above method, the transparency characteristic information may include: a yarn texture threshold for determining whether each pixel is on a thread of the transparent fabric; a gap texture threshold for determining whether each pixel is in a gap in the weave of the transparent fabric; a yarn background reference rate which is the percentage of pixels in the weave that reference the backing color; and a gap background reference rate which is the percentage of pixels in the gap that reference the backing color. The above step (e1-1) may include a step of determining the pixel background reference rate according to the texture value using a background reference rate determination curve determined by the yarn texture threshold, the gap texture threshold, the yarn background reference rate, and the gap background reference rate. This method allows for the determination of the pixel background reference ratio using the texture values ​​and transparency characteristics of the texture information.

[0074] (5) In the above method, step (d) may include (d1) determining the basic mixing ratio of the basic backing color when the color of the basic printed material is considered to be a mixture of the color of the transparent printed fabric and the basic backing color, according to the texture information and the basic proof image data, and (d2) creating the foreground proof image data by performing an operation to remove the basic backing color from the color represented by the basic proof image data according to the basic mixing ratio. The basic mixing ratio may be set to change depending on the brightness of the basic proof image data. According to this method, foreground color proof image data can be created by removing the basic backing color from the color represented in the basic proof image data using the basic color mixing ratio determined according to the texture information and the basic proof image data.

[0075] (6) In the above method, the basic proof image data may be data expressed in the output color space of the proof output device. Step (d) may include: (d1) determining the basic mixing ratio of the basic backing color when the color of the basic print is considered to be a mixture of the color of the translucent print fabric and the basic backing color, according to the texture information and the basic proof image data; (d2) generating a color correction media profile for the translucent fabric without the basic backing by performing a profile conversion on the media profile of the printing press for the translucent fabric using the basic backing color and the basic mixing ratio; and (d3) creating the foreground proof image data by performing a color management process that converts the basic proof image data to a device-independent color space using the color correction media profile. The basic mixing ratio may be set to change depending on the brightness of the basic proof image data. This method allows for the creation of foreground proof image data by applying color management processing to the base proof image data using a color correction media profile.

[0076] (7) According to a second embodiment of the present disclosure, a proof image data creation device is provided. This proof image data creation device includes: a basic proof image acquisition unit that acquires basic proof image data for reproducing the color of a basic printed material, which is obtained by applying a basic backing to a transparent printed fabric on which an image has been printed using a printing press, using a proof output device; a texture information acquisition unit that acquires texture information of the transparent fabric; a backing color information acquisition unit that acquires a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric; a color correction unit that creates foreground proof image data representing the color of the transparent printed fabric as observed without the backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information; and a synthesis unit that creates observation proof image data representing the color of an observation printed material, which is obtained by applying the observation backing to the transparent printed fabric by performing a synthesis process to synthesize the observation backing color with the color represented by the foreground proof image data according to the texture information. The synthesis unit is configured to perform the following: (e1) a process of determining the observed color mixing ratio of the observed backing color, assuming that the color of the observation print is a mixture of the color of the translucent print fabric and the observation backing color, according to the texture information and the basic proof image data; and (e2) a process of creating the observation proof image data by performing an operation to synthesize the basic backing color with the color represented by the foreground color proof image data according to the observed color mixing ratio. The observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

[0077] (8) According to a third embodiment of the present disclosure, a computer program for creating proof image data is provided. This computer program causes a computer to perform the following: (a) a process of acquiring basic proof image data for reproducing the color of a basic printed material, which is a transparent printed fabric with an image printed on it using a printing press and to which a basic backing has been applied, using a proof output device; (b) a process of acquiring texture information of the transparent fabric; (c) a process of acquiring a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric; (d) a process of creating foreground proof image data representing the color of the transparent printed fabric as observed without the backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information; and (e) a process of creating observation proof image data representing the color of an observation printed material, which is a transparent printed fabric with the observation backing applied, by performing a synthesis process to synthesize the observation backing color with the color represented by the foreground proof image data according to the texture information. The process (e) includes (e1) determining the observed color mixing ratio of the observed backing color, assuming that the color of the observation print is a mixture of the color of the translucent print fabric and the observation backing color, according to the texture information and the basic proof image data; and (e2) creating the observation proof image data by performing an operation to combine the basic backing color with the color represented by the foreground color proof image data according to the observed color mixing ratio. The observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

[0078] This disclosure can also be implemented in various forms other than those described above. For example, it can be implemented as a computer program that implements the functions of a proof image data creation device. It can also be implemented in the form of a non-transitory storage medium on which the computer program is recorded. [Explanation of symbols]

[0079] 100…Printing machine, 200…Proof image data creation device, 201…CPU, 202…Storage unit, 203…Input / output interface, 205…Display device, 210…Basic proof image acquisition unit, 220…Texture information acquisition unit, 230…Backing color information acquisition unit, 240…Color correction unit, 241…Profile correction unit, 242…Color management module, 250…Composition unit, 300…Proofing printing device, 500…Printing system

Claims

1. A method for creating proof image data, (a) A process to acquire basic proof image data for reproducing the color of a basic printed material, which is obtained by applying a basic backing to a translucent printed fabric on which an image has been printed using a printing press, using a proof output device, (b) A step of acquiring texture information of the transparent fabric, (c) A step of obtaining a basic backing color, which is the color of the basic backing, and an observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric, (d) A step of creating foreground color proof image data that represents the color of the translucent printed fabric as observed without backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information, (e) A step of creating observation proof image data representing the color of an observation print made by applying the observation backing to the transparent print fabric by performing a synthesis process that combines the observation backing color with the color represented by the foreground proof image data according to the texture information, Includes, The aforementioned step (e) is, (e1) A step of determining the observed mixing ratio of the observed backing color, when the color of the observation print is considered to be a mixture of the color of the transparent print fabric and the observation backing color, according to the texture information and the basic proof image data, (e2) A step of creating the observation proof image data by performing a calculation to combine the basic backing color with the color represented by the foreground proof image data according to the observation color mixing ratio, Includes, A method wherein the observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

2. The method according to claim 1, A method in which the observed color mixing ratio is set such that the observed color mixing ratio decreases as the brightness of the basic proof image data decreases.

3. The method according to claim 1, The texture information includes the transparency characteristics information of the transparent fabric and the texture value for each pixel. The above step (e1) is, (e1-1) Using the transparency characteristic information, a step of determining the pixel background reference rate, which is the percentage of each pixel that references the backing color, according to the texture value, (e1-2) A step of determining the observed color mixing ratio by multiplying the pixel background reference rate by an adjustment coefficient that changes depending on the brightness of the basic proof image data, Methods that include...

4. The method according to claim 3, The aforementioned transmission characteristics information is A yarn texture threshold for determining that each pixel corresponds to a thread of the transparent fabric, A gap texture threshold for determining that each pixel corresponds to a gap in the weave of the transparent fabric, The yarn background reference rate is the percentage of pixels corresponding to the yarn that reference the backing color, The gap background reference rate is the ratio to which the backing color is referenced in the pixels corresponding to the gap, Includes, The method includes a step (e1-1) of determining the pixel background reference rate according to the texture value using a background reference rate determination curve determined by the thread texture threshold, the gap texture threshold, the thread background reference rate, and the gap background reference rate.

5. The method according to claim 1, The aforementioned step (d) is, (d1) A step of determining the basic mixing ratio of the basic backing color when the color of the basic printed material is considered to be a mixture of the color of the transparent printed fabric and the basic backing color, according to the texture information and the basic proof image data, (d2) A step of creating foreground color proof image data by performing a calculation to remove the basic backing color from the color represented by the basic proof image data according to the basic color mixing ratio, Includes, A method wherein the basic color mixing ratio is set to change depending on the brightness of the basic proof image data.

6. The method according to claim 1, The aforementioned basic proof image data is data represented in the output color space of the proof output device. The aforementioned step (d) is, (d1) A step of determining the basic mixing ratio of the basic backing color when the color of the basic printed material is considered to be a mixture of the color of the transparent printed fabric and the basic backing color, according to the texture information and the basic proof image data, (d2) A step of generating a color correction media profile for the translucent fabric without using the basic backing by performing a profile conversion on the media profile of the printing press for the translucent fabric using the basic backing color and the basic color mixing ratio, (d3) A step of creating foreground color proof image data by performing a color management process that converts the basic proof image data into a device-independent color space using the color correction media profile, Includes, A method wherein the basic color mixing ratio is set to change depending on the brightness of the basic proof image data.

7. A proof image data creation device, A basic proof image acquisition unit acquires basic proof image data for reproducing the color of a basic printed material, which is obtained by applying a basic backing to a transparent printed fabric on which an image has been printed using a printing press, using a proof output device. A texture information acquisition unit that acquires texture information of the transparent fabric, A backing color information acquisition unit acquires the basic backing color, which is the color of the basic backing, and the observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric. A color correction unit creates foreground color proof image data representing the color of the translucent printed fabric as observed without backing by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information, A synthesis unit creates observation proof image data representing the color of an observation print with the observation backing applied to the transparent print fabric by performing a synthesis process that combines the observation backing color with the color represented by the foreground proof image data according to the texture information, Equipped with, The aforementioned synthesis section is (e1) A process to determine the observed mixing ratio of the observed backing color, when the color of the observation print is considered to be a mixture of the color of the transparent print fabric and the observation backing color, according to the texture information and the basic proof image data, (e2) A process to create the observation proof image data by performing an operation to combine the basic backing color with the color represented by the foreground proof image data according to the observation color mixing ratio, It is configured to perform the following actions: A proof image data creation device in which the observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

8. A computer program that creates proof image data, (a) A process to acquire basic proof image data for reproducing the color of a basic printed material, which is obtained by applying a basic backing to a translucent printed fabric on which an image has been printed using a printing press, using a proof output device, (b) A process for obtaining the texture information of the transparent fabric, (c) A process for obtaining the basic backing color, which is the color of the basic backing, and the observation backing color, which is the color of the observation backing used in the observation environment of the transparent printed fabric. (d) A process to create foreground color proof image data representing the color of the translucent printed fabric as observed without backing, by performing a color correction process to remove the basic backing color from the color represented by the basic proof image data according to the texture information, (e) A process to create observation proof image data representing the color of an observation print made by applying the observation backing to the transparent print fabric, by performing a synthesis process to combine the observation backing color with the color represented by the foreground proof image data according to the texture information, Have the computer run it, The process (e) is, (e1) A process to determine the observed mixing ratio of the observed backing color, when the color of the observation print is considered to be a mixture of the color of the transparent print fabric and the observation backing color, according to the texture information and the basic proof image data, (e2) A process to create the observation proof image data by performing an operation to combine the basic backing color with the color represented by the foreground proof image data according to the observation color mixing ratio, Includes, A computer program in which the observed color mixing ratio is set to change depending on the brightness of the basic proof image data.

Images