JP2009171556A - Print control apparatus, print system and print control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a print control apparatus capable of ensuring spectrum reproducibility and visual reproducibility. <P>SOLUTION: A color difference ΔE between a target chromatic value indicated by photometric data MD acquired by applying colorimetric processing to a target TG under a plurality of light sources and a predicted chromatic value in printing by a printer based on an ink quantity set ϕ is calculated for each of the light sources. If the color difference for each of the light sources is calculated, an evaluation value E(ϕ) obtained by linearly combining the color differences is calculated. The ink quantity set ϕ is calculated as an optimum solution for minimizing the evaluation value E(ϕ). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printing system and a printing control program, and more particularly to a printing system and a printing control program for reproducing a target.

A printing method focusing on spectral reproducibility has been proposed (see Patent Document 1). In this document, a printer color (CMYKOG) is used so as to fit a spectral reflectance (target spectrum) of a target using a printing model in order to perform printing that spectrally and colorimetrically matches a target image. The combination of is optimized. In this way, by performing printing based on the printer color (CMYKOG), the target image can be spectrally reproduced, and as a result, a highly reproducible printing result can be obtained.
Special table 2005-508125 gazette

  However, the types of color materials such as ink that can be used in a printing apparatus such as a printer are limited, and it is difficult to accurately reproduce the spectral reflectance of the target in all visible wavelength ranges. For this reason, there has been a case where the spectral reflectance fitting does not reach a sufficient level, and the color reproducibility remains insufficient. In particular, trying to fit spectral reflectance up to a wavelength range that hardly contributes to human vision, the reproduction accuracy of spectral reflectance in the wavelength range that greatly contributes to human vision is reduced. There was a problem that the reproducibility was felt poor.

  The present invention has been made in view of the above problems, and provides a printing system and a printing control program that ensure visual reproducibility while ensuring spectral reproducibility.

  In order to solve the above-described problem, the target color value acquisition unit acquires a target color value composed of each color value indicated by the target under a plurality of light sources. The print control unit refers to a lookup table that defines the correspondence between the target color value and the color material amount set. Accordingly, the color material amount set corresponding to the target color value is acquired, and the color material amount set is designated to the printing apparatus to perform printing. In the look-up table, the color material amount set, and each color value under each light source reproduced on the recording medium when printing is executed by designating the color material amount set to the printing apparatus; A correspondence relationship with the target color value having high closeness is defined. According to the color material amount set, a visually reproducible print result can be obtained under each light source. In addition, by performing printing based on the color material amount set that can realize the closeness to the target color value not only with a single light source but also with a plurality of light sources, the reproducibility of spectral reflectance is similar as a result. Become.

  The target color value acquisition means may acquire the target color value by performing colorimetry while actually irradiating the target with the plurality of light sources, or may be a target under a plurality of light sources from a user or the like A color value may be accepted as the target color value. Furthermore, the spectral reflectance of the target may be measured, and the color value when each light source is irradiated to the spectral reflectance may be obtained by calculation. The printing apparatus only needs to attach at least a plurality of the color materials to the recording medium, and the present invention can be applied to various printing apparatuses such as an ink jet printer, a laser printer, and a sublimation printer.

  In addition, as a preferable example of the evaluation value, a color difference under each light source between the target color value and a predicted color value that the printing apparatus is predicted to reproduce on the recording medium based on the color material amount set. You may apply what is calculated based on. Furthermore, as a preferred example, a linear combination of color differences under each light source between the target color value and the predicted color value may be applied as the evaluation value. In this way, the closeness to the target color value under a plurality of light sources can be comprehensively evaluated. Further, when calculating the evaluation value by linearly combining the color differences under each light source, it is desirable that the weight for each light source can be adjusted. By doing so, it is possible to attach importance to the closeness to the target color value with a specific light source, or to neglect it.

  In predicting the predicted color value, first, the spectral reflectance that the printing apparatus reproduces on the recording medium is predicted as the predicted spectral reflectance based on the color material amount set, and then the predicted color value is predicted. A color value when each light source is irradiated with respect to the spectral reflectance may be calculated as the predicted color value. In this way, the color value under a plurality of light sources can be easily calculated. Furthermore, as a preferred embodiment, not only the target color value but also the target spectral reflectance acquisition unit acquires the spectral reflectance of the target as the target spectral reflectance, and other color matching functions that approximate the target spectral reflectance The predicted color value may be calculated so as to contribute more than the color matching function. By doing in this way, the reproducibility of the spectral reflectance in the wavelength region where the target spectral reflectance takes a large value can be improved.

  Furthermore, the technical idea of the present invention can be realized not only by a specific printing control apparatus but also by a method thereof. That is, the present invention can also be specified as a method having steps corresponding to the respective units performed by the above-described print control apparatus. Of course, when the above-described printing control apparatus reads the program and realizes each means described above, the technical features of the present invention can be applied to a program for executing a function corresponding to each means and various recording media on which the program is recorded. It goes without saying that the idea can be embodied. Needless to say, the print control apparatus of the present invention can be distributed not only by a single apparatus but also by a plurality of apparatuses. For example, each unit included in the print control apparatus can be distributed in both the printer driver executed on the personal computer and the printer. In addition, each unit of the print control apparatus of the present invention can be included in a printing apparatus such as a printer.

Hereinafter, embodiments of the present invention will be described in the following order.
1. Configuration of print control device:
2. Print data generation processing:
3. Print control processing:
3-1.1 D-LUT creation processing:
3-2. Print control data generation processing:
4). Spectral printing model:
5. Variations:
5-1. Modification 1:
5-2. Modification 2:
5-3. Modification 3:
5-4. Modification 4:
5-5. Modification 5:
5-6. Modification 6:
5-7. Modification 7:

1. Configuration of Print Control Device FIG. 1 shows a hardware configuration of a print control device according to an embodiment of the present invention. In FIG. 1, the print control apparatus is mainly composed of a computer 10, and the computer 10 includes a CPU 11, a RAM 12, a ROM 13, a hard disk drive (HDD) 14, a general-purpose interface (GIF) 15, a video interface (VIF) 16, and an input interface. (IIF) 17 and a bus 18. The bus 18 implements data communication between the elements 11 to 17 constituting the computer 10, and communication is controlled by a chip set (not shown). The HDD 14 stores program data 14a for executing various programs including an operating system (OS), and the CPU 11 executes calculations according to the program data 14a while expanding the program data 14a in the RAM 12. . The GIF 15 provides an interface conforming to the USB standard, for example, and connects the external printer 20 and the colorimeter 30 to the computer 10. The VIF 16 connects the computer 10 to an external display 40 and provides an interface for displaying an image on the display 40. The IIF 17 connects the computer 10 to an external keyboard 50a and a mouse 50b, and provides an interface for the computer 10 to acquire input signals from the keyboard 50a and the mouse 50b.

  FIG. 2 shows a software configuration of a program executed by the computer 10 together with a schematic data flow. In the figure, a computer 10 mainly includes an OS P1, a sample printing application (APL) P2, a 1D-LUT generation application (LUG) P3a, a printer driver (PDV) P3b, a colorimeter driver (MDV) P4, and a display driver ( (DDV) P5 is being executed. The OS P1 provides an image equipment interface (GDI) P1a and a spooler P1b as one of APIs that can be used by each program. The GDI P1a is called in response to a request from the APL P2, and further in response to a request from the GDI P1a. PDV P3b and DDV P5 are called. The GDI P1a provides a general-purpose mechanism for the computer 10 to control image output in an image output device such as the printer 20 or the display 40, while the PDV P3b or DDV P5 is a process specific to the model of the printer 20 or the display 40. Etc. The spooler P1b is interposed between the APL P2, the PDV P3b, and the printer 20 and executes job control and the like. APL P2 is an application program for printing the sample chart SC, generates print data PD in the RGB bitmap format, and outputs the print data PD to the GDI P1a. In generating the print data PD, the target colorimetric data MD is acquired from the MDV P4. The MDV P4 controls the colorimeter 30 in response to a request from the APL P2, and outputs the color measurement data MD obtained by the control to the APL P2.

  The print data PD generated by the APL P2 is output to the PDV P3b via the GDI P1a and the spooler P1b, and the PDV P3b executes processing for generating print control data CD that can be output to the printer 20 based on the print data PD. . The print control data CD generated by the PDV P3b is output to the printer 20 via the spooler P1b provided by the OS P1, and the printer 20 prints the sample chart SC on the printing paper by performing an operation based on the print control data CD. Let Although the overall processing flow has been schematically described above, the processing executed by each of the programs P1 to P4 will be described in detail below using a flowchart.

2. Print Data Generation Processing FIG. 3 shows the flow of print data generation processing executed by APL P2. As shown in FIG. 2, the APL P2 includes a UI unit (UIM) P2a, a measurement control unit (MCM) P2b, and a print data generation unit (PDG) P2c. These modules P2a, P2b, and P2c are shown in FIG. Each step shown in 3 is executed. In step S100, the UIM P2a displays a UI screen for accepting a print instruction to print the sample chart SC via the GDI P1a and the DDV P5. On the UI screen, a display showing a template of the sample chart SC is provided.

  FIG. 4 shows an example of the UI screen. In the figure, the template TP is displayed, and the template TP is provided with 12 frames FL1 to FL12 for laying out color patches. On the UI screen, the frames FL1 to FL12 can be selected by clicking the mouse 50b, and a selection window W for instructing whether or not to start color measurement when the frames FL1 to FL12 are clicked. Is displayed. The UI screen is also provided with a button B for instructing whether or not to print the sample chart SC. In step S110, the UIM P2a detects a click on each frame FL1 to FL12 by the mouse 50b, and if it is detected, a selection window W for instructing whether or not to start color measurement is displayed in step S120. Let In step S130, a click on the mouse 50b in the selection window W is detected. If cancel is clicked, the process returns to step S110. On the other hand, if the execution of color measurement is clicked, in step S135, the UIM P2a performs display for guiding the color measurement. In this embodiment, color measurement is performed under a single target TG under five types of light sources (standard daylight D50 light source, D55 light source, D65 light source, incandescent light bulb system A light source, and fluorescent lamp system F11 light source). Since it is necessary to perform this, the user is guided to perform color measurement sequentially by changing the light source.

In this embodiment, the color measurement target TG means an object surface that is a target for spectral reproduction. For example, an artificial object surface formed by another printing apparatus or a coating apparatus, a natural object surface, or the like. Is applicable. In step S140, color measurement is executed while sequentially irradiating five types of light sources on a certain target TG. At this time, the MCM P2b acquires colorimetric data MD including five colorimetric values (target color values) per single target from the MDV P4. Each target color value is desirably acquired in an absolute color space. In the present embodiment, L ^* a ^* b ^* values in the CIELAB color space are acquired as target color values constituting the colorimetric data MD. In addition, the target color value of the D65 light source, which is the most standard light source, is converted into an RGB value using a predetermined RGB profile, and the RGB value is acquired as a display RGB value. The RGB profile is a profile that defines a color matching relationship between the CIELAB color space as an absolute color space and the RGB color space of the present embodiment. For example, an ICC profile can be used.

  In step S145, the clicked frames FL1 to FL12 in the template TP are updated to a display filled with the display RGB values. As a result, the color of the target TG with the D65 light source, which is a standard light source, can be sensed on the UI screen. When step S145 is completed, a unique index is generated in step S150, and the index, the display RGB value, and the position information of the frames FL1 to FL12 clicked in step S110 are displayed as five target color values. Are stored in the RAM 12 in association with the colorimetric data MD consisting of When step S150 is completed, the process returns to step S110, and steps S120 to S150 are repeatedly executed. Thereby, the other frames FL1 to FL12 can be selected, and the color measurement of other targets TG can be performed for the other frames FL1 to FL12. In the present embodiment, twelve different types of targets TG1 to TG12 are prepared, and target color values with five types of light sources are acquired as colorimetric data MD for each of the targets TG1 to TG12. Accordingly, in step S150, the data in which the color measurement data MD including the five target color values, the unique index, and the display RGB value are associated with each other in the frames FL1 to FL12 are sequentially stored in the RAM. Become. The index only needs to be generated so that each value is unique. The index may be generated by increment or by a random number that does not overlap.

  FIG. 5 shows a state in which target color values obtained for a certain target TG are plotted in the CIELAB color space. As shown in the figure, even when the color is measured for a single target TG, different target color values are acquired depending on the light source at the time of color measurement. As described above, a phenomenon in which the target color values are different under a plurality of light sources is referred to as metamerism, and has different metamerism characteristics for each target TG. This metamerism depends on the spectral reflectance R (λ) of each target, and even if targets having the same target color value are obtained with a certain light source, the spectral reflectance R (λ) is different. Different target color values will be shown under other light sources.

FIG. 6 illustrates how the colorimetric values under a plurality of light sources are obtained from a target TG having a certain spectral reflectance. For example, a target TG has a target spectral reflectance R _t (λ) distribution that is not uniform in the entire visible wavelength region as shown in the figure. On the other hand, each light source has a different distribution of spectral energy P (λ), and the spectral energy of the reflected light of each wavelength when the target TG is irradiated with the D65 light source is the target spectral reflectance R _t (λ). And spectral energy P (λ) multiplied by each wavelength. Further, the spectral energy spectrum of the reflected light is convolved with the color matching functions x (λ), y (λ), z (λ) corresponding to the human spectral sensitivity characteristics, and normalized by the coefficient k. Thus, tristimulus values X, Y, and Z can be obtained. The above is expressed by the following equation (1).

By converting the tristimulus values X, Y, and Z by a predetermined conversion formula, L ^* a ^* b ^* values as color values can be obtained. As described above, at the time of the spectrum of the spectral energy of the reflected light, a different spectrum is generated for each light source, so that the finally obtained target color value also differs depending on the light source as shown in FIG. It becomes.

  In step S110, when the click of each of the frames FL1 to FL12 is not detected, the click of the button B for executing the printing of the sample chart SC is detected in step S160, and when it is not detected, the process returns to step S110. On the other hand, if it is detected that the button B for executing printing of the sample chart SC is detected, the PDG P2c generates print data PD in step S170.

  FIG. 7 schematically shows the configuration of the print data PD. In the figure, the print data PD is composed of a large number of pixels arranged in a dot matrix, and each pixel has 4 bytes (8 bits × 4) of information. The print data PD shows an image similar to the template TP shown in FIG. 4, and the pixels other than the regions corresponding to the frames FL1 to FL12 of the template TP have RGB values of colors corresponding to the template TP. ing. The gradation value of each RGB channel is expressed by 8 bits (256 gradations), and 3 bytes out of the 4 bytes described above are used to store the RGB values. For example, when colors other than the frames FL1 to FL12 of the template TP are expressed by uniform intermediate gray of (R, G, B) = (128, 128, 128), the frames FL1 to FL12 in the print data PD. Pixels other than the region corresponding to the color information of (R, G, B) = (128, 128, 128). The remaining 1 byte is not used.

  On the other hand, the pixels corresponding to the frames FL1 to FL12 of the template TP also have 4-byte information, and the index is usually stored using 3 bytes in which RGB values are stored. This index is unique for each of the frames FL1 to FL12 in step S150, and the PDG P2c acquires the index from the RAM 12 and stores the index corresponding to the pixel corresponding to each of the frames FL1 to FL12. For the pixels corresponding to the frames FL1 to FL12 in which the indexes are stored instead of the RGB values in this way, the flag indicating that the indexes are stored is set using the remaining 1 byte. This makes it possible to determine whether each pixel stores an RGB value or an index. In this embodiment, since 3 bytes can be used to store the index, it is necessary to generate an index that can be expressed with an information amount of 3 bytes or less in step S150. When the bitmap format print data PD can be generated as described above, the PDG P2c generates the index table IDB in step S180.

  FIG. 8 shows an example of the index table IDB. In the figure, for each unique index generated corresponding to each of the frames FL1 to FL12, display RGB corresponding to the target color value for each light source obtained by colorimetry and the target color value for the D65 light source. A value is stored. When the generation of the index table IDB is completed, the print data PD is output to the PDV P3b via the GDI P1a and the spooler P1b. Since the print data PD is not different from the normal RGB bitmap format in appearance, the GDI P1a and the spooler P1b provided by the OS P1 can be processed in the same manner as a normal print job. On the other hand, the index table IDB is directly output to the PDV P3b. In the present embodiment, the index table IDB is newly generated. However, a new correspondence between the index, the target color value, and the display RGB value may be added to the existing index table IDB. . The print data generation process and the print control process described later do not necessarily have to be executed consecutively in the same apparatus, and the print data generation process and the print control process are connected by a communication line such as a LAN or the Internet. It may be executed individually on a plurality of computers.

3. Print Control Process FIG. 9 shows the overall flow of the print control process executed by the LUG P3a and the PDV P3b. The LUG P3a takes charge of the 1D-LUT generation process (step S200), and the PDV P3b takes charge of one print control data generation process (step S300). The 1D-LUT generation process may be performed prior to the print control data generation process, or the 1D-LUT generation process and the print control data generation process may be performed in parallel.

3-1.1 D-LUT Generation Processing FIG. 10 shows the flow of 1D-LUT generation processing. As shown in FIG. 2, the LUG P3a includes an ink amount set calculation module (ICM) P3a1, a spectral reflectance prediction module (RPM) P3a2, a color calculation module (CCM) P3a3, an evaluation value calculation module (ECM) P3a4, and an LUT output module. (LOM) P3a5. In step S210, ICM P3a1 acquires the index table IDB. In step S220, one index is selected from the index table IDB, and colorimetric data MD associated with the index is acquired. In step S230, the ICM P3a1 performs a process of calculating an ink amount set that can reproduce the same color as the target color value indicated by the color measurement data MD. At that time, the above-described RPM P3a2, CCM P3a3, and ECM P3a4 are used.

FIG. 11 schematically shows a flow of processing for calculating an ink amount set capable of reproducing the same color as the target color value indicated by the colorimetric data MD. In response to the input of the ink amount set φ from the ICM P3a1, the RPM P3a2 predicts the spectral reflectance R (λ) when the printer 20 ejects ink onto a predetermined print sheet based on the ink amount set φ. The predicted spectral reflectance R _s (λ) is predicted, and the predicted spectral reflectance R _s (λ) is output to the CCM P3a3. The printer 20 of the present embodiment is an ink jet printer, and performs printing by ejecting C (cyan) M (magenta) Y (yellow) K (black) lc (light cyan) lm (light magenta) ink onto printing paper. . The ink amount set φ means a combination of ink amounts d _C , d _M , d _Y , d _K , d _lc , and d _lm of the CMYKlclm ink to be ejected. If the ink amount set φ is designated, the formation state of each ink dot on the printing paper can be predicted, so the RPM P3a2 can uniquely calculate the predicted spectral reflectance R _s (λ). For the prediction model (spectral printing model) applied by RPM P3a2, see 4. This will be explained in detail in the section.

When the predicted spectral reflectance R _s (λ) is obtained, the CCM P3a3 calculates a predicted color value when the object having the predicted spectral reflectance R _s (λ) is irradiated with the five light sources described above. Here, the L ^* a ^* b ^* value of the CIELAB color space is calculated as the predicted color value. The flow of calculating the predicted color value is the same as that shown in FIG. 6 and the above equation (1) (the target spectral reflectance R _t (λ) is replaced with the predicted spectral reflectance R _s (λ)). is there. That is, by multiplying the predicted spectral reflectance R _s (λ) by the spectrum of the spectral energy of each light source, performing convolution integration with a color matching function, and further converting the tristimulus values into L ^* a ^* b ^* values, The L ^* a ^* b ^* value as the predicted color value can be calculated. The predicted color value is calculated for each of the five light sources, and the predicted color value is output to the ECM P3a4.

The ECM P3a4 calculates the color difference ΔE between the target color value and the predicted color value indicated by the colorimetric data MD for each light source. In this embodiment, the color difference ΔE (ΔE ₂₀₀₀ ) is calculated based on the color difference formula of CIE DE2000. In addition, the color difference for each light source is expressed as ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , ΔE _F11 . When ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , and ΔE _F11 can be calculated for the color differences for each light source, the evaluation value E (φ) is calculated by the following equation (2).

In the above equation (2), w _{1 to} w ₅ are weighting factors for setting the weight of each light source. In this embodiment, w ₁ = w ₂ = w ₃ = w ₄ = w ₅ Shall be equalized. The evaluation value E (φ) is a value that decreases as the color differences ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , and ΔE _F11 for each light source decrease, and the target colorimetric value and the predicted color value are comprehensive for each light source. The closer it is to, the smaller the value. The calculated evaluation value E (φ) is returned to the ICMP 3a1. That is, the ICMP 3a1 outputs an arbitrary ink amount set φ to the RPM P3a2, the CCM P3a3, and the ECM P3a4, so that the evaluation value E (φ) is finally returned to the ICMP 3a1. The ICM P3a1 repeatedly executes to obtain the evaluation value E (φ) corresponding to an arbitrary ink amount set φ, so that the evaluation value E (φ) as the objective function is minimized. Calculate the optimal solution. As a method for calculating the optimum solution, for example, a nonlinear optimization method such as a gradient method can be used.

FIG. 12 schematically shows how the ink amount set φ is optimized in step S230. In the same figure, the transition of the target color value under each light source indicated by the target TG in the CIELAB color space and the predicted color value under each light source when the ink amount set φ is optimized is shown. According to the equation (2), since the color differences ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , and ΔE _F11 for all light sources can be reduced as an optimization condition, The ink amount set φ is optimized so that the color differences ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , ΔE _F11 under the light source are gradually reduced. In this way, it is possible to calculate an ink amount set φ that can be reproduced by the printer 20 with an appearance similar to that of the target TG in any light source. Note that the optimization termination condition may be the number of repetitions of the ink amount set φ update or the threshold value of the evaluation value E (φ).

  As described above, when the ICM P3a1 calculates the ink amount set φ that can reproduce the same color as the target color value indicated by the colorimetric data MD in step S230, it is described in the index table IDB in step S240. It is determined whether or not all of the indexes have been selected in step S220. If all of the indexes have not been selected, the process returns to step S220 to select the next index. In this way, it is possible to calculate the ink amount set φ that can reproduce the same color as the target color value for all indexes. That is, an ink amount set φ that can reproduce the same color as the target color value indicated by the colorimetric data MD is calculated for all the targets TG1 to TG12 that have undergone colorimetry in step S140 of the print data generation process (FIG. 2). can do. If it is determined in step S240 that the optimal ink amount set φ has been calculated for all indexes, the LOM P3a5 generates a 1D-LUT and outputs the 1D-LUT to the PDV P3b in step S250.

  FIG. 13 shows an example of a 1D-LUT. In the figure, an optimum ink amount set φ is stored corresponding to each index. That is, for each target TG1 to TG12, a 1D-LUT describing an ink amount set φ that can be reproduced by the printer 20 with an appearance similar to that of each target TG1 to TG12 can be prepared. When the 1D-LUT is output to the PDV P3b, the 1D-LUT generation process is completed, and the next print control data generation process (step S300) is executed.

3-2. Print Control Data Generation Processing FIG. 14 shows the flow of print control data generation processing. As shown in FIG. 2, the PDV P3b includes a mode discrimination module (MIM) P3b1, an index conversion module (ISM) P3b2, an RGB conversion module (CSM) P3b3, a halftone module (HTM) P3b4, and a rasterization module (RTM) P3b5. It is composed of In step S310, the mode determination module (MIM) P3b1 acquires the print data PD. In step S320, the MIM P3b1 selects one pixel from the print data PD. In step S330, the MIM P3b1 determines whether or not a flag indicating that the index is stored in the selected pixel is set. If it is determined that the flag is not raised, the CSM P3b3 refers to the 3D-LUT in step S340 and executes color conversion (separation) for the pixel.

FIG. 15 shows an example of a 3D-LUT. In the figure, the 3D-LUT describes a plurality of representative coordinates in the color space in which the correspondence between the RGB value and the ink amount set φ (d _C , d _M , d _Y , d _K , d _lc , d _lm ). The CSM P3b3 refers to the 3D-LUT and acquires the ink amount set φ corresponding to the RGB value of the pixel. At that time, the corresponding ink amount set φ is acquired by performing interpolation calculation for RGB values not directly described in the 3D-LUT. As a method for creating a 3D-LUT, JP 2006-82460 A or the like can be employed. In this publication, a 3D-LUT in which color reproducibility in a specific light source, gradation of reproducible color, graininess, light source independence of reproducible color, gamut, and ink duty are comprehensively improved. Is created.

  On the other hand, if it is determined in step S330 that the flag indicating that the index has been stored in the selected pixel is set, ISM P3b2 refers to the 1D-LUT in step S350, and the color for the pixel is determined. Perform conversion (separation). That is, the index is acquired from the pixel on which the flag indicating that the index is stored, and the ink amount set φ associated with the index is acquired by the 1D-LUT. In step S340 or step S350, if the ink amount set φ for the pixel can be acquired, it is determined in step S360 whether the ink amount set φ has been acquired for all the pixels. If there remains a pixel for which the ink amount set φ has not been acquired, the process returns to step S320 to select the next pixel.

  By repeatedly executing the above processing, the ink amount set φ can be obtained for all the pixels. When the ink amount set φ can be obtained for all the pixels, all the pixels are converted into the print data PD expressed by the ink amount set φ. As described above, by determining which one of the 1D-LUT and 3D-LUT is used for each pixel, with respect to the pixels corresponding to the frames F1 to F12 in which the index is stored, the respective light sources have the respective targets TG1 to TG12. Can be obtained, and color reproduction based on a 3D-LUT creation guideline (for example, emphasizing graininess) is performed for pixels storing RGB values. A possible ink amount set φ can be acquired.

  In step S370, the HTM P3b4 acquires print data PD in which each pixel is expressed by an ink amount set φ, and executes halftone processing. The HTM P3b4 can use a known dither method, error diffusion method, or the like for halftone processing. In the print data PD for which the halftone process has been completed, each pixel has an ejection signal indicating whether or not each ink is ejected. In step S380, the RTM P3b5 acquires the print data PD for which the halftone process is completed, and executes a process of assigning the ejection signal in the print data PD to each scan pass and each nozzle of the print head of the printer 20. As described above, the print control data CD that can be output to the printer 20 can be generated, and the print control data CD to which signals necessary for controlling the printer 20 are attached is output to the spooler P1b and the printer 20. As a result, the printer 20 ejects ink onto the printing paper to form a sample chart SC.

  As described above, the colors of the targets TG1 to TG12 can be reproduced in the region corresponding to the frames FL1 to FL12 of the sample chart SC formed on the printing paper. Further, since the areas corresponding to the frames FL1 to FL12 are printed with an ink amount set φ that follows the target color values under the plurality of light sources of the targets TG1 to TG12, the areas TG1 to TG12 Similar colors can be reproduced. That is, the color of the area corresponding to each of the frames FL1 to FL12 when the sample chart SC is viewed indoors reproduces the color when the targets TG1 to TG12 are viewed indoors, and when the sample chart SC is viewed outdoors. The colors of the regions corresponding to the frames FL1 to FL12 can be reproduced when the targets TG1 to TG12 are visually recognized outdoors. That is, it is possible to create a sample chart SC that does not select an observation light source.

  Ultimately, if the sample chart SC having the same spectral reflectance R (λ) as the targets TG1 to TG12 is reproduced, the same color as the targets TG1 to TG12 can be reproduced with any light source. . However, since the ink (color material type) that can be used by the printer 20 is limited to CMYKlclm, an ink amount set φ that can reproduce the same spectral reflectance R (λ) as the targets TG1 to TG12 is obtained. Is virtually impossible. In addition, even when the ink amount set φ that can reproduce the spectral reflectance R (λ) similar to the targets TG1 to TG12 is obtained in the wavelength range that does not affect the perceived color, it is useless in realizing the visual reproduction accuracy. . On the other hand, in the present invention, the requirement for optimizing the ink amount set φ is relaxed by visually obtaining the ink amount set φ that can reproduce the target color values under a plurality of realistic light sources, and visually. Sufficient accuracy can be achieved.

  On the other hand, in the region corresponding to the frames FL1 to FL12 of the sample chart SC formed on the printing paper, printing is performed with the ink amount set φ based on the 3D-LUT described above. For this reason, the printing performance for the area is based on the 3D-LUT. As described above, in the present embodiment, the area other than the frames FL1 to FL12 shows a uniform image of intermediate gray, but the printing performance targeted by the 3D-LUT can be satisfied in the area. That is, it is possible to realize printing in which the gradation of reproduced color, graininess, light source independence of reproduced color, gamut, and ink duty are comprehensively improved.

4). Spectral Printing Model FIG. 16 schematically shows a printing method of the printer 20 of this embodiment. In the figure, the printer 20 includes a print head 21 having a plurality of nozzles 21a, 21a,... For each CMYKlclm ink, and the amount of ink for each CMYKlclm ink ejected by the nozzles 21a, 21a,. There ink amount set φ mentioned above _{(d c, d m, d} y, d k, d lc, d lm) is controlled to an amount that conforms to be done on the basis of the print control data CD. The ink droplets ejected by the nozzles 21a, 21a,... Become fine dots on the printing paper, and an ink amount set φ (d _c , d _m , d _y , d _k , d _lc , d A print image having an ink coverage corresponding to _lm ) is formed on the printing paper.

Prediction model RPM P3a2 uses (spectral printing model), any ink amount set φ that can be used in the printer 20 of the embodiment _{(d c, d m, d} y, d k, d lc, d lm) in This is a prediction model for predicting the spectral reflectance R (λ) when printing is performed as the predicted spectral reflectance R _s (λ). In the spectral printing model, a spectral reflectance database DB obtained by actually printing a color patch at a plurality of representative points in the ink amount space and measuring the spectral reflectance R (λ) with a spectral reflectance meter is used. prepare. An arbitrary ink amount set φ (d _c , d) is accurately determined by performing prediction using the Cellular Yule-Nielsen Spectral Neugebauer Model using the spectral reflectance database DB. _{m, d y, d k,} d lc, predicts the predicted spectral reflectance in the case of performing printing with _{d lm) R s (λ)} .

FIG. 17 shows the spectral reflectance database DB. (Is a six-dimensional in the present embodiment, illustrated only CM surface. For ease of illustration) the spectral reflectance database DB as shown in the figure ink amount space ink amount set of grid points in (d _c , D _m , d _y , d _k , d _lc , d _lm ) are look-up tables in which spectral reflectances R (λ) obtained by actually printing / measuring are described. For example, five grid points that divide each ink amount axis are generated. Here 5 ¹³ also lattice points are generated, it is necessary to print / measurement of color patches of huge amount, actually can be discharged simultaneously mountable ink number and simultaneously by the printer 20 ink Since the duty is limited, the number of grid points to be printed / measured is reduced.

  Further, only some of the lattice points are actually printed / measured, and the other lattice points are spectrally reflected R (λ) based on the spectral reflectance R (λ) of the actually printed / measured lattice points. Thus, the number of color patches that are actually printed / measured may be reduced. The spectral reflectance database DB needs to be prepared for each printing sheet that can be printed by the printer 20. Strictly speaking, the spectral reflectance R (λ) is determined by the spectral transmittance of the ink film (dot) formed on the printing paper and the reflectance of the printing paper, and the surface physical properties of the printing paper (depending on the dot shape). ) And reflectivity. Next, prediction based on the cell division Yule-Nielsen spectral Neugebauer model using the spectral reflectance database DB will be described.

  The RPM P3a2 executes prediction based on the cell division Yule-Nielsen spectral Neugebauer model using the spectral reflectance database DB in response to a request from the ICM P3a1. In this prediction, a prediction condition is acquired from ICM P3a1, and this prediction condition is set. Specifically, printing paper and ink amount set φ are set as printing conditions. For example, when prediction is performed using glossy paper as printing paper, a spectral reflectance database DB created by printing color patches on glossy paper is set.

When it is set the spectral reflectance database DB, the ink amount set which is input from ICM P3a1 phi applying _{(d c, d m, d} y, d k, d lc, d lm) of the spectral printing model. The cell splitting Yule-Nielsen spectroscopic Neugebauer model is based on the well-known spectroscopic Neugebauer model and the Yule-Nielsen model. In the following description, for simplification of description, a model in which three types of CMY inks are used will be described. However, a similar model is used as a model using an arbitrary ink set including CMYKlclm of the present embodiment. It is easy to expand. For cell splitting Yule-Nielsen spectral Neugebauer model, Color Res Appl 25, 4-19, 2000 and R Balasubramanian, Optimization of the spectral Neugebauer model for printer characterization, J. Electronic Imaging 8 (2), 156- See 166 (1999).

ここで、ａ_iはｉ番目の領域の面積率であり、Ｒ_i（λ）はｉ番目の領域の分光反射率である。添え字ｉは、インクの無い領域（ｗ）と、シアンインクのみの領域（ｃ）と、マゼンタインクのみの領域（ｍ）と、イエローインクのみの領域（ｙ）と、マゼンタインクとイエローインクが吐出される領域（ｒ）と、イエローインクとシアンインクが吐出される領域（ｇ）と、シアンインクとマゼンタインクが吐出される領域（ｂ）と、ＣＭＹの３つのインクが吐出される領域（ｋ）をそれぞれ意味している。また、ｆ_c，ｆ_m，ｆ_yは、ＣＭＹ各インクを１種類のみ吐出したときにそのインクで覆われる面積の割合（「インク被覆率(Ink area coverage)」と呼ぶ）である。 FIG. 18 is a diagram illustrating a spectral Neugebauer model. The spectral Neugebauer model, optional ink amount sets _{(d c, d m, d} y) predicted spectral reflectance of the printed matter when printed with R _s (lambda) is given by the following equation (3).

Here, a _i is the area ratio of the i-th region, and R _i (λ) is the spectral reflectance of the i-th region. The subscript i includes an area without ink (w), an area only with cyan ink (c), an area only with magenta ink (m), an area only with yellow ink (y), magenta ink and yellow ink. A region (r) where yellow ink and cyan ink are ejected, a region (b) where cyan ink and magenta ink are ejected, and a region where three inks CMY are ejected (region) (r) k) respectively. Further, f _c , f _m , and _fy are the proportions of the area covered with only one CMY ink when it is ejected (referred to as “Ink area coverage”).

The ink coverages f _c , f _m , and _fy are given by the Murray-Davis model shown in FIG. In the Murray-Davies model, for example, the ink area coverage f _c of the cyan ink is a nonlinear function of the ink amount d _c of the cyan, be converted to the ink amount d _c in the ink coverage f _c, for example by one-dimensional lookup table Can do. Ink coverage f _c, f _m, f _y is the ink amount d _c, d _m, reason for the non-linear function of d _y is spread enough ink in the case where a small amount of ink ejected to the unit area, This is because, when a large amount of ink is ejected, the ink is overlapped and the area covered with the ink does not increase so much. The same applies to other types of MY inks.

ここで、ｎは１以上の所定の係数であり、例えばｎ＝１０に設定することができる。（４ａ）式および（４ｂ）式は、ユール・ニールセン分光ノイゲバウアモデル(Yule-Nielsen Spectral Neugebauer Model)を表す式である。 When the Yule-Nielsen model for the spectral reflectance is applied, the equation (3) can be rewritten as the following equation (4a) or (4b).

Here, n is a predetermined coefficient of 1 or more, and can be set to n = 10, for example. Equations (4a) and (4b) are equations representing the Yule-Nielsen Spectral Neugebauer Model.

  The Cellular Yule-Nielsen Spectral Neugebauer Model adopted in the present embodiment is obtained by dividing the ink amount space of the above-described Yule-Nielsen Spectral Neugebauer Model into a plurality of cells. is there.

FIG. 19A shows an example of cell division in the cell division Yule-Nielsen spectroscopic Neugebauer model. Here, for simplification of description depicts the cell division in a two-dimensional ink amount space including two axes of the ink amount d _c, d _m of the CM inks. It notes that it for ink coverage f _c, is f _m with at Murray-Davis model described above the ink amount d _c, a unique relationship with d _m, the ink coverage f _c, also be considered as an axis indicating the f _m . White circles are cell division grid points (called “lattice points”), and a two-dimensional ink amount (coverage) space is divided into nine cells C1 to C9. The ink amount set (d _c , d _m ) corresponding to each lattice point is an ink amount set corresponding to the lattice point defined in the spectral reflectance database DB. That is, the spectral reflectance R (λ) of each lattice point can be obtained by referring to the above-described spectral reflectance database DB. Therefore, the spectral reflectances R (λ) ₀₀ , R (λ) ₁₀ , R (λ) ₂₀ ... R (λ) _{33 at} each lattice point can be acquired from the spectral reflectance database DB.

In fact, performs six-dimensional ink amount space of even the cell division CMYKlclm In this embodiment, the ink amount set phi (d _c coordinates also the six-dimensional lattice _{points, d m, d y, d} k, d lc , D _lm ). Then, the ink amount set for each grid point _{φ (d c, d m,} d y, d k, d lc, d lm) spectral reflectivity of the grid points corresponding to R (lambda) is the spectral reflectance database DB (e.g. (From glossy paper).

FIG. 19 (B) shows the relationship between the ink area coverage f _c and the ink amount d _c which are used in the cell division model. Here, one kind of the ink amount in the range 0 to D _cmax of ink is also divided into three sections, the virtual used in the cell division model by non-linear curve which increases monotonically from 0 for each section to the 1 A typical ink coverage _fc is determined. For other inks, the ink coverages f _m and f _y are obtained in the same manner.

FIG. _19C shows the predicted spectral reflectance R _s (λ) when printing is performed with an arbitrary ink amount set (d _c , d _m ) in the center cell C5 of FIG. 19A. The calculation method is shown. The predicted spectral reflectance R _s (λ) when printing is performed with the ink amount set (d _c , d _m ) is given by the following equation (5).

Here, the ink coverages f _c and f _m in the equation (5) are values given by the graph of FIG. The spectral reflectances R (λ) ₁₁ , (λ) ₁₂ , (λ) ₂₁ , and (λ) ₂₂ corresponding to the four lattice points surrounding the cell C5 are acquired by referring to the spectral reflectance database DB. Can do. As a result, all values constituting the right side of the equation (5) can be determined, and the predicted spectral reflection when printing is performed with an arbitrary ink amount set φ (d _c , d _m ) as the calculation result. The rate R _s (λ) can be calculated. By sequentially shifting the wavelength λ in the visible wavelength region, the predicted spectral reflectance R _s (λ) in the visible light region can be obtained. If the ink amount space is divided into a plurality of cells, the predicted spectral reflectance R _s (λ) can be calculated more accurately than when the ink amount space is not divided. As described above, when the RPM P3a2 predicts the predicted spectral reflectance R _s (λ) in response to the request of the ICM P3a1, the CCM P3a3 continues to use the predicted spectral reflectance R (λ). Predictions can be performed.

5. Modified example 5-1. Modification 1
In the above equation (2), the weighting factors w _{1 to} w ₅ of each light source are set to equal values, but the weighting factors w _{1 to} w ₅ may be set to be unequal. If the values of the weight counts w _{1 to} w ₅ are set large, the contribution ratio to the increase in the evaluation value E (φ) of the color differences ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , and ΔE _{F11 in} the corresponding light source is increased. be able to. Therefore, in order to minimize the evaluation value E (φ), the color differences ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , and ΔE _{F11 of} the light source in which the values of the weighting factors w _{1 to} w ₅ are set to be large are particularly small values. According to the ink amount set φ that is optimized based on the evaluation value E (φ), the color differences ΔE _D50 and ΔE _D55 for the light source in which the values of the weighting factors w ₁ to w ₅ are set large , ΔE _D65 , ΔE _A , ΔE _F11 can be printed.

For example, the weight counts w _{1 to} w ₅ may be set by user designation. The user may designate the weighting factors w _{1 to} w ₅ according to the importance of the D50 light source, D55 light source, D65 light source, A light source, and F11 light source, respectively. For example, when the user wants to emphasize the color reproduction accuracy outdoors, the weighting factors w ₄ and w ₅ of the A light source and the F11 light source may be set small. Of course, a combination of weight counts w _{1 to} w ₅ preset in advance may be indirectly set by selecting an environment for observing the printed matter. Thereby, even when the user has no knowledge about the light source, it is possible to set appropriate weighting factors w _{1 to} w ₅ .

5-2. Modification 2
In the above-described embodiment, the target color value of the target TG under a plurality of light sources is designated by the colorimeter 30, but the user may directly designate the target color value using the keyboard 50a or the like. For example, when color value data measured in the past for the target TG is already prepared, the target color value can be specified by inputting the data. Furthermore, since the target color value under a plurality of light sources can be uniquely calculated based on the spectral reflectance R (λ) of the target TG, a spectral reflectance meter is used instead of the colorimetric measurement of the colorimeter 30 in step S140. Thus, the spectral reflectance R (λ) of the target TG may be measured.

FIG. 20 schematically shows a calculation procedure of the target color value when the spectral reflectance R (λ) of the target TG is measured. In the figure, spectral energy P _D50 (λ), P _D55 (standard light source D50 light source, D55 light source, D65 light source, incandescent light bulb A light source, fluorescent lamp F11 light source). λ), P _D65 (λ), P _A (λ), and P _F11 (λ) are shown. In this modification, the spectral reflectance R (lambda) was measured as target spectral reflectances R _t (λ) for each target TG1～TG12, spectral energy P of the light sources with the target spectral reflectance R _t (λ) _The target color value is calculated by applying _D50 (λ), P _D55 (λ), P _D65 (λ), P _A (λ), and P _F11 (λ) to the above equation (1). Processing similar to that in the above-described embodiment can be performed on the target color value obtained in this way.

5-3. Modification 3
FIG. 21 schematically shows how the CCM P3a3 calculates the predicted color value based on the predicted spectral reflectance R _s (λ) in the modified example. In the figure, the target spectral reflectance R _t (λ) obtained in the above-described modification is shown, and the target spectral reflectance R _t (λ) and each color matching function x (λ), y ( Correlation coefficients c _x , c _y , and c _z with λ) and z (λ) are calculated by CCM P3a3. Since each color matching function x (λ), y (λ), z (λ) has a different wavelength band in which the value increases, the wavelength band in which the value increases becomes the target spectral reflectance R _t (λ). When they are similar, it can be considered that the correlation coefficients c _x , c _y , and c _z become high. The predicted color value according to this deformation is calculated by the following equation (6).

In the above equation (6), when the predicted color value is calculated, the correlation coefficients c _x , c _y and c _z are multiplied. Thus the correlation coefficient c _x, c _y, by multiplying the c _z, the correlation coefficient c _x, c _y, color the like to the extent that corresponding to c _z function x (λ), y (λ ), z (λ) can be emphasized. Therefore, the correlation coefficient between the target spectral reflectances _{R t (λ) c x,} c y, c z increases, i.e. equal to the wavelength band value increases is similar to the target spectral reflectance R _t (λ) The contribution of the color functions x (λ), y (λ), and z (λ) to the predicted color value can be increased. In other words, it is possible to calculate a predicted color value having a high contribution rate in a wavelength band in which the value of the target spectral reflectance R _t (λ) is large. By using such a predicted color value, in the optimization of the ink amount set φ, it is possible to attach importance to a wavelength band in which the value of the target spectral reflectance R _t (λ) is particularly large.

前記の（７）式の評価値Ｅ（φ）によれば、光源間の色変動の近似性も考慮したインク量セットφの最適化を行うことができる。 5-4. Modification 4
FIG. 22 schematically illustrates the evaluation value E (φ) according to the modification. In the figure, target light source color variation vectors V _t 1 to V _t 4 are calculated in the CIELAB space to connect the target color values of each light source in the order of D50 → D55, D55 → D65, D65 → A, and A → F11. Similarly, predicted inter-light source color variation vectors V _s 1 to V _s 4 are also calculated for predicted color values. Then, in each pair of color between the target light source variation vector V _t 1 to V _t 4 and the prediction source between color variation vector V _s 1 to V _s 4, the light source variability evaluation was indexing the size and direction of the similarity An index S (φ) is calculated. Then, the evaluation value E (φ) is defined as the following equation (7).

According to the evaluation value E (φ) of the expression (7), the ink amount set φ can be optimized in consideration of the approximation of the color variation between the light sources.

5-5. Modification 5
In addition, what is necessary is just to make it print with the same color as area | regions other than the frame F about the area | region corresponding to the frame F which is not selected in embodiment mentioned above. Of course, it is not necessary to request spectral reproducibility for the region corresponding to the unselected frame F, so that color conversion using a 3D-LUT is performed in the same manner as the region other than the frame F. That's fine. Furthermore, a pattern, characters, marks, or the like may be printed in a region other than the region corresponding to the frame F in which the target TG is designated. For example, characters indicating what the target TG is may be written near the frame F in which the target TG is designated. Furthermore, the light sources used for the evaluation are not limited to the five types used in the above-described embodiment, and other types of light sources may be used. Of course, the number of light sources used for the evaluation is not limited to five. For example, three types may be used to improve the reproducibility of the target TG with a narrower observation light source, or eight types of target TGs with more light sources. Reproducibility may be achieved.

5-6. Modification 6
23 to 24 show the software configuration of a printing system according to a modification of the present invention. As shown in FIG. 23, a configuration corresponding to the LUG P3a of the above-described embodiment may be provided as an internal module of the PDV P3bb. As shown in FIG. 24, a configuration corresponding to the LUG P3a of the above-described embodiment may be executed in another computer 110. In this case, the computer 10 and the computer 110 are connected by a predetermined communication interface CIF, and the 1D-LUT generated by the LUG P3a of the computer 110 is transmitted to the computer 10 via the communication interface CIF. The communication interface CIF may intervene via the Internet. In this case, the computer 10 can perform color conversion with reference to the 1D-LUT acquired from the computer 110 on the Internet. Further, all software configurations P1 to P5 may be executed in the printer 20. Of course, the present invention can also be realized when hardware that executes processing equivalent to the software configurations P1 to P5 is incorporated in the printer 20.

5-7. Modification 7
25A and 25B show a UI screen (displayed in step S100) according to this modification. In the previous embodiment, the target color values under a plurality of light sources are actually measured, and an index table in which the target color values and the indexes are associated with each other is prepared. An index table in which is registered may be prepared. In this modification, it is assumed that an index table is prepared in advance, in which an index given for each paint manufactured by a paint manufacturer and a correspondence relationship between target color values obtained by measuring the application surface of each paint are registered. In the index table, display RGB values are also registered as in the above-described embodiment. When the index table is prepared in advance, in step S100, processing for selecting a paint (index) to be reproduced on the sample chart SC is performed by the APL P2.

  First, as shown in FIG. 25A, a plurality of sample image data and thumbnails of user image data are displayed as a list. The sample image data is image data stored in the HDD 14 in advance, and the user image data is image data captured from an image input device such as a digital still camera. Further, image data downloaded from the Internet may be used as user image data. Each thumbnail can be clicked with the mouse 50b, and a frame is displayed on the thumbnail clicked last. In the UI screen of FIG. 25A, a determination button is provided. By clicking the determination button, selection of user image data or sample image data corresponding to a thumbnail in which a frame is displayed is confirmed.

  When the selection is confirmed, the UI screen shown in FIG. 25B is displayed. On the UI screen, an enlarged thumbnail of the confirmed user image data or sample image data is displayed. In the UI screen of FIG. 25B, a manual selection button and an automatic selection button are provided. When the manual selection button is clicked, a mouse pointer is displayed on the enlarged thumbnail, and designation of the upper left corner and lower right corner of the rectangular designated area desired by the user is accepted by drag and drop. Then, the RGB value for displaying each pixel belonging to the rectangular area designated by APL P2 on the display 40 is inquired to DDV P5. The DDV P5 outputs an RGB value for displaying each pixel of the enlarged thumbnail to the display 40, and can specify the RGB value of each pixel belonging to the designated area. When the RGB value of each pixel belonging to the designated area is obtained, the APL P2 averages the RGB value of each pixel and sets the average value as the designated RGB value. On the other hand, when the automatic selection button is clicked, APL P2 acquires DDV P5 as the RGB values of all the pixels of the enlarged thumbnail, and among these, the most representative RGB value is set as the designated RGB value. For example, a histogram of the RGB values of all the pixels of the enlarged thumbnail may be created, and the RGB value having the highest frequency may be set as the designated RGB value. When the designated RGB value is obtained as described above, the display RGB value closest to the designated RGB value is searched in the index table. Here, an index with the smallest Euclidean distance in the RGB space between the designated RGB value and each display RGB value is searched. The display RGB value having the shortest Euclidean distance from the designated RGB value is expressed as the most approximate RGB value. Next, each display RGB value (including the most approximate RGB value) is converted into an HSV value by a known conversion formula.

  FIG. 26 shows a state in which the display RGB values converted into HSV values are plotted in the HSV space. In the figure, the HSV value obtained by converting the most approximate RGB value is indicated by a point Q0. In the HSV space, a sectional fan-shaped space within ± 5 degrees with respect to the hue angle (H value) of the HSV value (Q0) obtained by converting the most approximate RGB value is specified. That is, a space in which the hue angle approximates the most approximate RGB value is specified. Next, two auxiliary axes SA intersecting the lightness axis (V axis) and the saturation axis (S axis) at 45 degrees are generated, and the first to fourth regions AR1 delimited by the auxiliary axis SA. ~ AR4 is defined. The first area AR1 has a characteristic that the hue angle H is close to the most approximate RGB value and the brightness V is larger than the most approximate RGB value. Further, the second area AR2 has a characteristic that the hue angle H is close to the most approximate RGB value, and the saturation S is slightly smaller than the most approximate RGB value. The third area AR3 has a characteristic that the hue angle H is close to the most approximate RGB value and the brightness V is smaller than the most approximate RGB value. The fourth area AR4 has a characteristic that the hue angle H is close to the most approximate RGB value and the saturation S is larger than the most approximate RGB value.

  An RGB value for display corresponding to an HSV value belonging to the first area AR1 and having the lightness V closest to the lightness V of the point Q0 (first approximate RGB value, expressed as a point Q1 in the HSV space) in the index table. Search for. Similarly, a display RGB value (third approximate RGB value, expressed as a point Q3 in the HSV space) corresponding to an HSV value belonging to the third area AR3 and having the brightness V closest to the brightness V of the point Q0. Search in the index table. It can be said that the first approximate RGB value has a hue angle H that approximates the most approximate RGB value and has a slightly higher brightness V than the most approximate RGB value. On the contrary, it can be said that the third approximate RGB value has a hue angle H that is close to the most approximate RGB value and has a slightly lower brightness V. Next, a display RGB value corresponding to an HSV value belonging to the second area AR2 and having the saturation S closest to the saturation S of the point Q0 (second approximate RGB value, expressed as a point Q2 in the HSV space). ) In the index table. Similarly, a display RGB value corresponding to an HSV value belonging to the fourth area AR4 and having the saturation S closest to the saturation S of the point Q0 (fourth approximate RGB value, expressed as a point Q4 in the HSV space). ) In the index table. It can be said that the second approximate RGB value is such that the hue angle H approximates the most approximate RGB value and the saturation S is slightly smaller than the most approximate RGB value. On the other hand, the fourth approximate RGB value can be said to have a hue angle H approximate to the most approximate RGB value and a slightly lower saturation S.

  Further, as shown in FIG. 26, in the HSV space, an annular shape having lightness V and saturation S within ± 5 with respect to the lightness V and saturation S of the HSV value (Q0) obtained by converting the most approximate RGB value. Identify the space. That is, the space where the lightness V and the saturation S approximate the most approximate RGB value is specified. Next, a region where the hue angle H is larger than the HSV value obtained by converting the most approximate RGB value in the annular space is a fifth region AR5, and a region where the hue angle H is small is a sixth region AR6. Then, the display RGB value (fifth approximate RGB value, denoted as point Q5 in the HSV space) corresponding to the HSV value belonging to the fifth area AR5 and having the hue angle H closest to the point Q0 is indicated in the index table. Search for. Similarly, a display RGB value (sixth approximate RGB value, expressed as a point Q6 in the HSV space) corresponding to an HSV value belonging to the sixth area AR6 and having the hue angle H closest to the point Q0 is an index table. Search in. It can be said that the fifth approximate RGB value is such that the lightness V and the saturation S are approximate to the most approximate RGB value and the hue angle H is slightly larger than the most approximate RGB value. On the other hand, the sixth approximate RGB value can be said to have a lightness V and a saturation S that are similar to the most approximate RGB value and have a hue angle H slightly smaller than the most approximate RGB value. . When the most approximate RGB value and the first to sixth approximate RGB values can be specified as described above, the next UI screen is displayed.

  FIG. 27 shows a UI screen displayed next. In the UI screen, the HSV space is shown locally, and the HSV axis is shown. At the intersection of these axes, a rectangular attention display patch PT0 filled with the most approximate RGB value is displayed. On the other hand, a rectangular first display patch PT1 painted with the first approximate RGB value is displayed on the side with the higher lightness V on the V axis, and painted with the third approximate RGB value on the side with the lower lightness V on the V axis. A rectangular third display patch PT3 is displayed. In addition, a rectangular fourth display patch PT4 painted with the fourth approximate RGB value is displayed on the side with the higher lightness S on the S axis, and painted with the second approximate RGB value on the side with the lower lightness S on the S axis. A rectangular second display patch PT2 is displayed. Furthermore, a rectangular fifth display patch PT5 painted with the fifth approximate RGB value is displayed on the side where the hue angle H on the H axis is large, and the sixth approximate RGB value is displayed on the side where the hue angle H on the H axis is small. A solid rectangular sixth display patch PT6 is displayed.

  The attention display patch PT0 is displayed by a display RGB value registered in the index table that is closest to the designated RGB value designated by the user. That is, the color of the paint closest to the designated RGB value designated by the user among the indexes (paints) registered in the index table is shown. On the other hand, the first to sixth display patches PT1 to PT6 are paints that approximate the designated RGB value (most approximate RGB value) designated by the user among the indexes (paints) registered in the index table. Thus, it can be said that the color of the paint is slightly different in hue H, lightness V, and saturation S from the most approximate RGB value. Thereby, it is possible to visually recognize the paint color approximated to the designated RGB value designated by the user and the paint color approximated thereto.

  In the UI screen of FIG. 27, an adjustment button and a sample chart print button are provided. When the adjustment button is clicked, APL P2 monitors the operation on the mouse 50b. Although not shown, the mouse 50b includes a wheel in addition to the click button. After clicking the adjustment button, the APL P2 monitors the moving direction of the mouse 50b and the rotation of the wheel until the next click button is operated. Then, the UI screen of FIG. 27 is updated as follows according to the moving direction of the mouse 50b and the rotation of the wheel.

  When the mouse 50b moves a predetermined amount in the upward (backward) direction, the most approximate RGB value is replaced with the current first approximate RGB value. After the most similar RGB value is replaced with the current first approximate RGB value, new first to sixth approximate RGB values are calculated by the above-described procedure. Then, the UI screen of FIG. 27 is updated so as to display the attention display patch PT0 and the first to sixth display patches PT1 to PT6 based on the new most approximate RGB value and the first to sixth approximate RGB values. As a result, the attention display patch PT0 and the first to sixth display patches PT1 to PT6 are shifted to the color indicated by the paint on the high brightness side. On the other hand, when the mouse 50b moves downward by a predetermined amount, the most approximate RGB value is replaced with the current third approximate RGB value, and the new attention display patch PT0 and the first to sixth displays are displayed. The UI screen in FIG. 27 is updated so as to display the patches PT1 to PT6. As a result, the attention display patch PT0 and the first to sixth display patches PT1 to PT6 are shifted to the colors indicated by the low-lightness-side paint.

  When the mouse 50b moves to the right by a predetermined amount, the most approximate RGB value is replaced with the current fourth approximate RGB value, and then the new attention display patch PT0 and the first to sixth display patches PT1 to PT6 are replaced. The UI screen in FIG. 27 is updated so that it is displayed. Similarly, when the mouse 50b moves to the left by a predetermined amount, the most approximate RGB value is replaced with the current second approximate RGB value, and then the new attention display patch PT0 and the first to sixth display patches PT1. The UI screen in FIG. 27 is updated to display .about.PT6. When the wheel of the mouse 50b rotates by a predetermined amount in the back direction, the most approximate RGB value is replaced with the current fifth approximate RGB value, and then a new attention display patch PT0 and first to sixth display patches PT1 to PT1 are replaced. The UI screen in FIG. 27 is updated to display PT6. When the wheel of the mouse 50b rotates a predetermined amount in the forward direction, the most approximate RGB value is replaced with the current sixth approximate RGB value, and then the new attention display patch PT0 and the first to sixth display patches PT1 to PT1 are replaced. The UI screen in FIG. 27 is updated to display PT6.

  In this way, the color of the attention display patch PT0 can be changed to any one of the first to sixth display patches PT1 to PT6. That is, the color of the attention display patch PT0 can be shifted to the high / low brightness side, the high / low saturation side, and the large / small side of the hue angle among the display RGB values registered in the index table. . That is, the color of the attention display patch PT0 can be changed along the H axis, the S axis, and the V axis by the operation of the mouse 50b, and the color of the attention display patch PT0 can be adjusted sensuously. . Since the attention display patch PT0 and the first to sixth display patches PT1 to PT6 are displayed based on the display RGB values retrieved from the index table, the color indicated by one of the paints is displayed. When the click button of the mouse 50b is clicked, the UI screen update process of FIG. 27 based on the operation of the mouse 50b is terminated. As a result, when the attention display patch PT0 that the user is satisfied with is displayed, the update of the UI screen in FIG. 27 can be terminated.

  When the sample chart print button is clicked on the UI screen in FIG. 27, the process proceeds to step S170 in FIG. 3 to generate print data. Here, basically, print data PD for printing the UI screen of FIG. 27 is generated. That is, the attention display patch PT0 and the first to sixth display patches PT1 to PT6 are printed. Here, among the pixels of the print data PD, the pixels other than the region corresponding to the target display patch PT0 and the first to sixth display patches PT1 to PT6 store the RGB values. On the other hand, for pixels corresponding to the attention display patch PT0 and the first to sixth display patches PT1 to PT6, display RGB values for displaying the attention display patch PT0 and the first to sixth display patches PT1 to PT6 in the index table. The index associated with is stored instead of the RGB value. By doing in this way, with respect to the attention display patch PT0 and the first to sixth display patches PT1 to PT6, printing for reproducing the target color values under a plurality of light sources of the paint associated with each index is executed.

  In the sample chart SC printed as described above, the user may print the attention display patch PT0 that reproduces the target color values under a plurality of light sources of the paint that shows colors close to the color specified in the region in the enlarged thumbnail. it can. In addition, it is possible to print the first to sixth display patches PT1 to PT6 that reproduce the target color values under a plurality of light sources of the paint showing a color close to the target display patch PT0. Select the desired paint from the first to sixth display patches PT1 to PT6 that show colors close to the target display patch PT0 even if the reproduction result of the target display patch PT0 is slightly different from what the user intended. can do.

2 is a block diagram illustrating a hardware configuration of a printing control apparatus. FIG. 2 is a block diagram illustrating a software configuration of a print control apparatus. FIG. 6 is a flowchart illustrating a flow of print data generation processing. It is a figure which shows an example of UI screen. It is the figure which plotted the target color value. It is a figure explaining the calculation for calculating a color value based on a spectral reflectance. It is a figure which shows print data. It is a figure which shows an index table. 5 is a flowchart illustrating an overall flow of print control processing. It is a flowchart which shows the flow of 1D-LUT generation processing. It is a schematic diagram showing a flow of processing for optimizing the ink amount set. It is a schematic diagram which shows a mode that an ink amount set is optimized. It is a figure which shows 1D-LUT. 6 is a flowchart illustrating a flow of print control data generation processing. It is a figure which shows 3D-LUT. It is a schematic diagram which shows the printing system of a printer. It is a figure which shows a spectral reflectance database. It is a figure which shows a spectral Neugebauer model. It is a figure which shows a cell division | segmentation Yule-Nielsen spectroscopic Neugebauer model. It is a schematic diagram explaining the prediction color value concerning a modification. It is a schematic diagram which shows the weight function concerning a modification. It is a figure explaining the evaluation value concerning a modification. It is a figure which shows the software structure of the printing system concerning a modification. It is a figure which shows the software structure of the printing system concerning a modification. It is a figure which shows UI screen concerning a modification. It is a figure which shows HSV space. It is a figure which shows UI screen concerning a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Computer, 11 ... CPU, 12 ... RAM, 13 ... ROM, 14 ... HDD, 15 ... GIF, 16 ... VIF, 17 ... IIF, 18 ... Bus, P1 ... OS, P1a ... GDI, P1b ... Spooler, P2 ... APL, P2a ... UIM, P2b ... MCM, P2c ... PDG, P3b ... PDV, P3a1 ... ICM, P3a2 ... RPM, P3a3 ... CCM, P3a4 ... ECM, P3a5 ... LOM, P4 ... MDV, P5 ... DDV.

Claims (8)

A printing control device that designates a color material amount set that is a combination of the amount of use of the color materials to the printing device when performing printing by attaching a plurality of color materials to a recording medium in the printing device,
Target color value acquisition means for acquiring a target color value composed of each color value indicated by the target under a plurality of light sources;
The color material amount set corresponding to the target color value is acquired by referring to a look-up table that defines a correspondence relationship between the target color value and the color material amount set, and the color material amount set is printed And a print control means for performing printing by designating the apparatus,
In the lookup table,
The target having high closeness between the color material amount set and each color value under each light source reproduced on the recording medium when printing is executed by designating the color material amount set to the printing apparatus A printing control apparatus characterized in that a correspondence relationship with a color value is defined.   Each color value under each light source that constitutes the target color value and each color light source that is reproduced on the recording medium when printing is executed by specifying the color material amount set to the printing apparatus. The print control apparatus according to claim 1, wherein the closeness is evaluated by an evaluation value based on each color value and a color difference.   The print control apparatus according to claim 2, wherein the evaluation value is calculated by linearly combining the color differences under each light source.   The print control apparatus according to claim 1, wherein a weight for calculating the evaluation value by linearly combining the color differences under each light source is adjusted for each light source.   Each color value under each light source reproduced on the recording medium when printing is performed by designating the color material amount set to the printing device designates the color material amount set to the printing device. The spectral reflectance that is reproduced on the recording medium when printing is executed and the object is predicted by calculating the color value when each light source is irradiated to the object having the spectral reflectance. The printing control apparatus according to any one of claims 1 to 4. Further comprising target spectral reflectance acquisition means for acquiring the spectral reflectance of the target as the target spectral reflectance,
The color matching function approximated to the target spectral reflectance is more greatly contributed than other color matching functions when calculating the color value when each light source is irradiated to the predicted object having the spectral reflectance. The printing control apparatus according to claim 5. A printing apparatus that performs printing by attaching a plurality of color materials to a recording medium and a color material amount set that is a combination of the usage amounts of the color materials are designated to the printing apparatus, and printing based on the color material amount set is performed. A printing system comprising a print control device to be executed,
Target color value acquisition means for acquiring a target color value composed of each color value indicated by the target under a plurality of light sources;
The color material amount set corresponding to the target color value is obtained by referring to a look-up table that defines the correspondence relationship between the target color value and the color material amount set, and the color material amount set is printed And a print control means for performing printing by designating the apparatus,
In the lookup table,
The target having high approximation between the color material amount set and each color value under each light source reproduced on the recording medium when printing is executed by specifying the color material amount set to the printing apparatus. A printing system characterized in that a correspondence relationship between color values is defined. When printing is performed by attaching a plurality of color materials to a recording medium in a printing apparatus, a color material amount set that is a combination of the usage amounts of the color materials is designated to the printing apparatus, and based on the color material amount set A computer-readable print control program for causing a computer to execute a function of executing printing,
A target color value acquisition function for acquiring a target color value composed of each color value indicated by the target under a plurality of light sources;
The color material amount set corresponding to the target color value is obtained by referring to a look-up table that defines the correspondence relationship between the target color value and the color material amount set, and the color material amount set is printed In addition to causing the computer to execute a print control function that causes the device to execute printing,
In the lookup table,
The target having high approximation between the color material amount set and each color value under each light source reproduced on the recording medium when printing is executed by specifying the color material amount set to the printing apparatus. A computer-readable print control program characterized in that a correspondence relationship between color values is defined.

Images