JP4924414B2 - Print control apparatus, print system, and print control program - Google Patents

Description

  The present invention relates to a printing control apparatus, a printing system, and a printing control program, and more particularly to a printing control apparatus, 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.
Japanese Patent Application Laid-Open No. 2004-228561 describes that inks showing different spectral reflectances while showing the same color value under predetermined conditions are used for preventing counterfeiting of securities and the like.
Special table 2005-508125 gazette JP 2000-327978 A

  According to the technique of Patent Document 1 described above, it is possible to obtain a highly reproducible print result in colorimetry. However, since the ink set itself has a predetermined spectral reflectance distribution, how the ink sets are combined. However, there is a wavelength range that cannot be completely reproduced. Therefore, even if printing is performed based on the spectral reflectance distribution of existing colors (colors that have already been printed, colors that exist in nature, colors that are already colored in paintings, cultural properties, documents, etc.) Depending on the light source, it may look different from existing colors. However, as disclosed in Patent Document 2, metamerism is intentionally generated to prevent counterfeiting, or existing colors that originally had metamerism (printed colors, colors existing in nature, paintings, cultural assets, and documents) It is also meaningful to accurately reproduce a color that has already been colored, a color of a paint, etc.).

  The present invention has been made in view of the above problems, and provides a print control apparatus, a print system, and a print control program capable of controlling the occurrence of metamerism.

  In order to solve the above-described problem, the print control device of the present application differs from each other while having the same color value under a predetermined light source for a plurality of color materials in the printing device controlled by the print control device of the present application. The configuration is such that it includes at least one set of color matching color materials having spectral reflectance characteristics, and includes receiving means, spectral reflectance printing control means, and color value printing control means. The accepting unit accepts an instruction of a spectral reflectance to be printed or a color value to be printed. The spectral reflectance printing control unit, when receiving the spectral reflectance, causes the printing apparatus to execute printing based on the color material amount set determined based on the spectral reflectance. The color value printing control unit, when receiving a color value, causes the printing apparatus to perform printing based on the color material amount set determined based on the color value. As described above, the same color value under a predetermined light source and the same color value having different spectral reflectance characteristics show different color values under other predetermined light sources. Therefore, the occurrence of metamerism can be controlled by controlling the use ratio of these color matching materials. In other words, when the target to be printed is instructed by spectral reflectance, printing is performed so as to reproduce the spectral reflectance and the metamerism is controlled to reproduce the desired metamerism, or to perform printing that is unlikely to generate metamerism. Or print without worrying about metamerism. On the other hand, when a print target is designated by a color value, printing is performed so that the color value is reproduced under a predetermined light source. Therefore, if printing is not concerned with metamerism, it is possible to perform printing without being aware of metamerism by designating a print target with a color value. Of course, printing in which a desired color value is reproduced under a predetermined light source (printing without worrying about metamerism) may be performed by printing in which a print target is designated by spectral reflectance.

  The accepting unit may be instructed to specify the spectral reflectance or color value of the print target based on the spectral reflectance measurement actually performed on the print target, or from the user or the like. Selection of rate and color value may be accepted. 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.

  Further, as an example suitable for executing printing in which color values of the color matching color material are designated, the color value printing control means is configured so that the color matching color materials having substantially the same color value are substantially the same over one printing. Printing using the ratio may be executed, or printing using the same color material having substantially the same color value according to the remaining amount or in substantially the same amount may be executed. That is, in printing in which metamerism may occur (printing that does not require matching of spectral reflectances), there is no problem even if printing is performed in which each color matching color material is virtually regarded as one color material. Accordingly, all of the color matching color materials can be used as a color material having one color value, and the number of printable sheets based on the color value increases. At that time, printing is performed so that the frequency of use of each color material is not biased, or the color material having a large amount of color material is used first, so that any one of the color materials is used. It is possible to prevent the occurrence of the shortage of color materials. In particular, if printing is performed using substantially the same color material having substantially the same color value at almost the same ratio throughout printing, the usage ratio of each color material does not change in the middle of the printed matter, which is attributed to metamerism. Therefore, it is possible to prevent the possibility that the points that should have the same color value appear to be different colors depending on the light source or the shades are reversed.

  Further, when the receiving unit determines whether the print instruction is received by the spectral reflectance or the color value, the receiving unit is instructed by the print data by analyzing the received print data. You may comprise so that a spectral reflectance or a color value may be received. The analysis of the print data may be an analysis of the flag by attaching a flag that can distinguish the spectral reflectance and the color value in advance with respect to the print data, or the spectral reflectance and the color value. A format specific to each data may be determined by analysis.

  Further, in order to improve the prediction accuracy of the color material amount set, the spectral reflectance printing control unit is based on an evaluation value that evaluates the closeness to the target spectral reflectance while taking into account different weights depending on wavelengths. The color material amount set indicating the spectral reflectance that approximates the instructed spectral reflectance on the recording medium may be predicted, and the printing apparatus may execute printing based on the predicted ink amount set. In order to predict the color material amount set based on an evaluation value that evaluates the closeness to the target spectral reflectance while imposing different weights for each wavelength, priority is given to a wavelength region with high importance of closeness. Can be made.

  In addition, as a preferable example of the weight, one set based on spectral sensitivity characteristics of the human eye may be applied. By doing so, the spectral reflectance can be preferentially approximated with respect to a wavelength that is sensitive to human spectral sensitivity, and a printed result with high visual reproducibility can be obtained. As a more specific example, the weight may be set based on a linear combination of color matching functions corresponding to tristimulus values. In this way, it is possible to set the weight capable of giving a comprehensive importance to the wavelength range corresponding to each color matching function corresponding to the tristimulus values.

  Furthermore, the weight may be set based on the target spectral reflectance. For example, for a wavelength range having a spectrum with a strong target spectral reflectance, it is considered that the closeness of the spectral reflectance will ultimately have a large effect on vision, so that the wavelength range may be prioritized and approximated. desirable. The weight may be set based on a spectral energy distribution of a predetermined light source. By setting the weight according to the spectral energy distribution of a predetermined light source, it is possible to preferentially approximate the wavelength region where the light source has a strong spectrum, and to improve the visual reproducibility of the light source. it can. The weight may be set based on a linear combination of spectral energy of a plurality of light sources in consideration of reproducibility not only with a single light source but also with a plurality of light sources.

  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: Modified example 2:
5-3: Modification 3:
5-4: Modification 4:
5-5: Modification 5:

1. Configuration of print control device:
FIG. 1 shows a hardware configuration of a print control apparatus 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 spectral reflectometer 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, the computer 10 mainly executes an OS P1, a sample printing application (APL) P2, a printer driver (PDV) P3, a spectral reflectometer driver (MDV) P4, and a display driver (DDV) P5. 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 P3 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 P3 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 P3, 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 spectral reflectometer 30 in response to a request from the APL P2, and outputs the spectral reflectance data RD obtained by the control to the APL P2.

  The print data PD generated by the APL P2 is output to the PDV P3 via the GDI P1a and the spooler P1b, and the PDV P3 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 P3 is output to the printer 20 via the spooler P1b provided by the OS P1, and the printer 20 performs an operation based on the print control data CD to print the sample chart SC on the printing paper. 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 receiving a print instruction for printing 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. Each frame FL1 to FL12 can be selected by clicking the mouse 50b on the UI screen, and a selection window for instructing whether or not to start the spectral reflectance measurement when the frames FL1 to FL12 are clicked. W 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 spectral reflectance measurement in step S120. Is displayed. 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, when the spectral reflectance measurement execution is clicked, in step S140, the MCM P2b sends the target spectral reflectance R _t (the spectral reflectance R (λ) of the target TG to the spectral reflectance meter 30 via the MDV P4. (λ) is measured, and spectral reflectance data RD storing the target spectral reflectance R _t (λ) is acquired.

When the measurement of the target spectral reflectance R _t (λ) in step S140 is completed, the color value (L ^* a ^* b ^* value) in the CIELAB color space when the most standard light source D65 light source is irradiated is calculated. . Then, the L ^* a ^* b ^* value 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.

FIG. 5 schematically shows how the display RGB values are calculated from the spectral reflectance data RD in step S140. For example, it is assumed that as a result of measuring the target spectral reflectance R _t (λ) for the target TG, spectral reflectance data RD indicating the distribution of the target spectral reflectance R _t (λ) is obtained as shown in the figure. The target TG means an object surface that is a target for spectral reproduction, and corresponds to, for example, the surface of an artificial object formed by another printing apparatus, a coating apparatus, application of paint, or the like, or the surface of a natural object. On the other hand, the D65 light source has a non-uniform distribution of spectral energy P (λ) in the visible wavelength region as shown in the figure, and the spectral energy of reflected light of each wavelength when the target TG is irradiated with the D65 light source is This is a value obtained by multiplying the target spectral reflectance R _t (λ) and the spectral energy P (λ) for 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 are obtained. The above is expressed by the following equation (1).

By converting the tristimulus values X, Y, and Z according to a predetermined conversion formula, an L ^* a ^* b ^* value indicating the color when the target TG is irradiated with the D65 light source can be obtained, and an RGB profile is used. By doing so, RGB values for display can be obtained. 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, position information of the frames FL1 to FL12 clicked in step S110, and display RGB values are associated with the spectral reflectance data RD. Store in the RAM 12. 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 target spectral reflectance R _t (λ) of the target TG on which the object surface of another color is reproduced for the other frames FL1 to FL12 can be measured.

In the present embodiment, 12 different types of targets TG1 to TG12 are prepared, and the target spectral reflectance R _t (λ) for each of the targets TG1 to TG12 is acquired as spectral reflectance measurement data RD. And Therefore, in step S150, data in which the spectral reflectance measurement data RD and the unique index for each frame FL1 to FL12 are associated with each other are sequentially stored in the RAM. 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.

  In step S110, if a click on each of the frames FL1 to FL12 is not detected, a click on button B for executing printing of sample chart SC is detected in step S160, and if 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. 6 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 有 す る have 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. 7 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, the target spectral reflectance R _t (λ) obtained by measurement and the L ^* a ^* b ^* value in the D65 light source. RGB values for display corresponding to are stored. When the generation of the index table IDB is completed, the print data PD is output to the PDV P3 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 P3. In this embodiment, the index table IDB is newly generated. However, a new correspondence relationship between the index, the target spectral reflectance R _t (λ), and the display RGB value is added to the existing index table IDB. You may make it do. 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. 8 shows the overall flow of the print control process executed by the PDV P3. As shown in FIG. 2, the PDV P3 includes a 1D-LUT generation unit (LUG) P3a and a print control data generation unit (CDG) P3b, and performs the 1D-LUT generation process (step S200) shown in FIG. The LUG P3a is in charge, and the CDG P3b is in 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. 9 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, an evaluation value calculation module (ECM) P3a3, and an LUT output module (LOM) P3a4. ing. In step S210, ICM P3a1 acquires the index table IDB. In step S220, one index is selected from the index table IDB, and spectral reflectance data RD 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 spectral reflectance R (λ) similar to the target spectral reflectance R _t (λ) indicated by the spectral reflectance data RD. At that time, the above-described RPM P3a2 and ECM P3a3 are used.

Here, the ink set Ink of the present invention will be described. The ink set Ink is composed of C1, C2, C3, M1, M2, M3, Y1, Y2, Y3, K, lc, and lm colors. In this ink set Ink, C1, C2, and C3 all have substantially the same color value (coordinates in absolute color space such as L ^* a ^* b ^* ) under a predetermined standard light source (all can be regarded as cyan). Different spectral reflectance distributions are used. Similarly, M1, M2, and M3 have different color reflectance distributions while having a color value of M under a predetermined standard light source, and Y1, Y2, and Y3 have a color value of Y under a predetermined standard light source. However, the spectral reflectance distributions are different from each other. Hereinafter, the relationship between C1, C2, and C3, the relationship between M1, M2, and M3, and the relationship between Y1, Y2, and Y3 are referred to as a color matching relationship, and a set of inks having a color matching relationship is referred to as a color matching ink set. .

10 is a graph showing an example of the spectral reflectance distribution of the color matching ink set in C, FIG. 11 is a graph showing an example of the spectral reflectance distribution of the color matching ink set in M, and FIG. It is a graph which shows an example of the spectral reflectance distribution of a color matching ink set. As shown in FIGS. 10 to 12, each of the inks constituting the color matching ink set exhibits a spectral reflectance distribution having a narrow peak as compared with the case of using one ink for each ink color. Yes. Further, although the peak positions appearing in the spectral reflectance distribution are different among the inks constituting the color matching ink set, the L ^* a ^* b ^* values are substantially equal to each other. Therefore, in printing that does not require consideration of metamerism, each ink constituting the color matching ink set can be handled as the same color.

  In the above description, CMY is described as having the same color ink set, but of course, any one of CMY may be configured to have the same color ink set, or CMYKlclm Arbitrary combinations may be made up of color matching ink sets. In addition, although each of the inks constituting the color matching ink set is described as an example exhibiting the same color value when irradiated with the D65 light source, under what light source each ink constituting the color matching ink set is used. It is possible to appropriately select whether the colors are the same, and various light sources such as a standard daylight D50 light source, a D55 light source, an incandescent light bulb A light source, and a fluorescent lamp F11 light source can be used. Of course, not only such a standard light source, but also a light source that is desired to maintain a color matching relationship can be arbitrarily selected.

FIG. 13 schematically shows a flow of processing for calculating an ink amount set that can reproduce a spectral reflectance R (λ) similar to the target spectral reflectance R _t (λ) indicated by the spectral reflectance data RD. Yes. RPM P3a2 is an ink quantity set φ (d _C1 , d _C2 , d _C3 , d _M1 , d _M2 , d _M3 , d _Y1 , d _Y2 , d _Y3 , d _K , d _lc , d _lm ) from ICM P3a1. In response to the input, the spectral reflectance R (λ) when the printer 20 ejects ink onto a predetermined printing sheet is predicted based on the ink amount set φ, and the spectral reflectance R (λ) is predicted to be spectroscopic. and it outputs the ECM P3a3 as reflectivity R _s (λ). By using the same color ink set in this way, it is possible to perform high-precision fitting and more target spectral reflection compared to the conventional case where fitting with respect to the target spectral reflectance is performed with ink having a wide peak. The predicted spectral reflectance R _s (λ) having a high coincidence rate with the rate R _t (λ) can be reproduced. That is, good results can be obtained in the evaluation described below.

The ECM P3a3 calculates the difference D (λ) between the target spectral reflectance R _t (λ) and the predicted spectral reflectance R _s (λ) indicated by the spectral reflectance data RD for each wavelength λ, and weights each wavelength λ. Is multiplied by the difference D (λ). The square root of the mean square of this value is calculated as the evaluation value E (φ). The above calculation can be expressed by the following equation (2).

In the above equation (2), N means the finite number of sections of wavelength λ. In the above equation (2), the smaller the evaluation value E (φ), the smaller the difference between the target spectral reflectance R _t (λ) and the predicted spectral reflectance R _s (λ) at each wavelength λ. it can. That is, the smaller the evaluation value E (φ) is, from the spectral reflectance R (λ) reproduced on the recording medium when the printer 20 prints with the input ink amount set φ, and the corresponding target TG. It can be said that the obtained target spectral reflectance R _t (λ) is approximate. Further, according to the above equation (1), although the absolute color value indicated by the target TG corresponding to the recording medium when the printer 20 prints with the ink amount set φ according to the fluctuation of the light source both fluctuates. If the spectral reflectance R (λ) is approximated, it can be said that the same color is perceived relatively regardless of the variation of the light source. Therefore, according to the ink amount set φ in which the evaluation value (φ) becomes small, it can be said that a print result perceived in the same color as the target TG can be obtained in any light source.

前記の（３）式においては、等色関数ｘ（λ），ｙ（λ），ｚ（λ）を加算することにより、重み関数ｗ（λ）が定義されている。なお、前記の（３）式の右辺全体に所定の係数を乗算して、重み関数ｗ（λ）の値の範囲を正規化してもよい。前記の（１）式によれば、等色関数ｘ（λ），ｙ（λ），ｚ（λ）が大きい波長域ほど、色彩値（Ｌ^*ａ^*ｂ^*値）に大きく影響するということができる。従って、等色関数ｘ（λ），ｙ（λ），ｚ（λ）を加算した重み関数ｗ（λ）を使用すれば、色への影響が大きい波長域を重視した二乗誤差が評価可能な評価値Ｅ（φ）を得ることができる。例えば、人間の目に知覚されない近紫外波長域においてはｗ（λ）が０となり、当該波長域における差分Ｄ（λ）は評価値Ｅ（φ）の増大に寄与しないこととなる。 In the present embodiment, the weighting function w (λ) uses the following equation (3).

In the above equation (3), the weighting function w (λ) is defined by adding the color matching functions x (λ), y (λ), and z (λ). The range of the value of the weighting function w (λ) may be normalized by multiplying the entire right side of the equation (3) by a predetermined coefficient. According to the above equation (1), the wavelength range where the color matching functions x (λ), y (λ), and z (λ) are larger greatly affects the color value (L ^* a ^* b ^* value). Can do. Therefore, if a weighting function w (λ) obtained by adding the color matching functions x (λ), y (λ), and z (λ) is used, a square error that emphasizes a wavelength region that has a large influence on the color can be evaluated. An evaluation value E (φ) can be obtained. For example, w (λ) is 0 in the near ultraviolet wavelength region that is not perceived by human eyes, and the difference D (λ) in the wavelength region does not contribute to the increase in the evaluation value E (φ).

That is, even if the difference between the target spectral reflectance R _t (λ) and the predicted spectral reflectance R _s (λ) is not necessarily small in the entire visible wavelength range, If the reflectance R _t (λ) and the predicted spectral reflectance R _s (λ) are similar, a small evaluation value E (φ) can be obtained, and the spectral reflectance R in accordance with the perception of the human eye. The evaluation value E (φ) can be used as an index of the closeness of (λ). The calculated evaluation value E (φ) is returned to ICM P3a1. That is, the ICMP 3a1 outputs an arbitrary ink amount set φ to the RPM P3a2 and the ECM P3a3, whereby the evaluation value E (φ) is finally returned to the ICM P3a1. 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, various optimization methods can be used. For example, it is desirable to use a nonlinear optimization method such as a gradient method.

FIG. 14 schematically shows how the ink amount set φ is optimized in step S230. In the figure, as the ink amount set φ is optimized, the predicted spectral reflectance R _s (λ) when printing is performed with the ink amount set φ approaches the target spectral reflectance R _t (λ). . Further, by using the weighting function w (λ), the target spectral reflection of the predicted spectral reflectance R _s (λ) is increased in the wavelength region where the color matching functions x (λ), y (λ), and z (λ) are larger. The constraint on the rate R _t (λ) is stronger, and the difference between the predicted spectral reflectance R _s (λ) and the target spectral reflectance R _t (λ) is smaller. In this way, the predicted spectral reflectance R _s (λ) is preferentially applied to the target spectrum of the target TG in the wavelength range where the color matching functions x (λ), y (λ), and z (λ) are large and have a large effect on vision. Since it can be constrained to the reflectance R _t (λ), it is possible to calculate the ink amount set φ that makes the appearance close when irradiated with an arbitrary light source. As described above, it is possible to calculate the ink amount set φ that can be reproduced by the printer 20 with an appearance similar to 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 spectral reflectance R (λ) as that of the target TG in step S230, all the indexes described in the index table IDB in step S240 are obtained. In step S220, it is determined whether or not all items have been selected. If not all items have been selected, the process returns to step S220 to select the next index. In this way, it is possible to calculate an ink amount set φ that can reproduce the same color as the target TG for all indexes. That is, an ink amount set φ that can reproduce the same spectral reflectance R (λ) as that of the targets TG1 to TG12 is calculated for all the targets TG1 to TG12 subjected to 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 P3a4 generates a 1D-LUT and outputs the 1D-LUT to the CDG P3b in step S250.

FIG. 15 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, an ink amount set φ (d _C1 , d _C2 , d _C3 , d _M1 , d _M2 that can be reproduced by the printer 20 with an appearance similar to each target TG1 to TG12. , D _M3 , d _Y1 , d _Y2 , d _Y3 , d _K , d _lc , d _lm ) can be prepared. When the 1D-LUT is output to the CDG 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. 16 shows the flow of print control data generation processing. As shown in FIG. 2, the CDG P3b includes a mode discrimination module (MIM) P3b1, an index separation module (ISM) P3b2, an RGB separation module (CSM) P3b3, a halftone module (HTM) P3b4, and a rasterization module (RTM). P3b5, an ink remaining amount monitoring module (IWM) P3b6, and a color separation module (MSM) P3b7. 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. 17 shows an example of a 3D-LUT. In the drawing, 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 ψ (d _C , d _M , d _Y , d _K , d _lc , d _lm ). The CSM P3b3 refers to the 3D-LUT and obtains the ink amount set ψ corresponding to the RGB value of the pixel. At that time, the corresponding ink amount set ψ is obtained by performing an interpolation operation 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.

For the pixels that have undergone the color conversion by the 3D-LUT, the MSM P3b7 performs color separation to the same color ink (hereinafter referred to as equal color separation) in step S345, and the ink amount set ψ (d _C , d _M , d _Y , d _K , d _lc , d _lm ) from the ink amount set ψ (d _C1 , d _C2 , d _C3 , d _M1 , d _M2 , d _M3 , d _Y1 , d _Y2 , d _Y3 , d _K , d _lc , d _lm ). In addition, since it is not necessary to consider metamerism about the pixel by which color conversion was performed by 3D-LUT, you may use any color ink for the printing of the pixel designated by CMY. Therefore, according to the remaining amount of each color ink, it is possible to use the color ink at random or perform color separation such that a specific color ink is preferentially used.

Therefore, when performing the color separation, the MSM P3b7 obtains the ink remaining amount information from the IWM P3b6, and performs the color separation ratio for each color ink according to the ink remaining amount. For example, if the remaining amount of C1 is 40 ml, the remaining amount of C2 is 30 ml, and the remaining amount of C3 is 20 ml, the separation ratio is determined so as to preferentially use C1 having a large remaining amount of ink. As a specific example of the separation ratio, C1, C2, and C3 are used up at the same time by performing separation at a ratio of d _C1 : d _C2 : d _C3 = 3: 4: 6, It may be possible to preferentially use ink with a large remaining amount until the remaining amount of ink becomes equal.

  The IWM P3b6 that outputs ink remaining amount information grasps the remaining amount of each ink by monitoring the ink ejection status of the printer 20. In order to monitor the ink discharge status, for example, the ink provided by the printer 20 is monitored by the sensor provided in the printer 20, or the usage time of each print head, the number of discharges of each ink discharge nozzle, the number of prints on each print head, Or the like. The sensor of the printer 20 detects, for example, a change in intensity of light caused by an ink droplet passing between the light emitting element and the light receiving element provided with the nozzle for ejecting ink interposed therebetween, and controls the operation of each nozzle. This can be realized with a confirmation.

  Further, in order to prevent metamerism and to prevent the reversal of light and shade, it is preferable to use a constant ratio of each color ink in one printing. In other words, if the ratio of each color ink changes during printing separation, dots that should have the same color value may appear to be different colors depending on the light source, or the color density may be reversed. This is because there is a possibility of doing so.

As described above, the 3D-LUT is separated to CMY by the 3D-LUT in step S340, and the separation to the same color ink is performed in the subsequent step S345, so that the 3D-LUT does not become too large. That is, the separation including up equal color inks to be realized in 3D-LUT, if 3D-LUT of the five grid on each of the primary colors, in the case of CMYKlclm necessary information about the grid points ^{5 6} to which the in, information about the grid points of 5 ¹² becomes necessary when so provided equal color inks CMY colors is three, respectively, as described above.

  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. As in step S320 described above, by expressing the spectral reflectance of the target by using different color inks having different spectral reflectance distributions, an ink amount set φ that more accurately reflects the target metamerism is created.

  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.

In the region corresponding to the frames FL1 to FL12 of the sample chart SC formed on the printing paper as described above, the target spectral reflectances R _t (λ) of the targets TG1 to TG12 can be reproduced. That is, the areas corresponding to the frames FL1 to FL12 are printed with an ink amount set φ that follows the colors of the targets TG1 to TG12 under a plurality of light sources, and thus similar to the targets TG1 to TG12 under each light source. Such colors can be reproduced. For example, when the sample chart SC is viewed indoors, the colors of the areas corresponding to the frames FL1 to FL12 reproduce the colors when the targets TG1 to TG12 are viewed indoors, and 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.

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 target spectral reflectance R _t (λ is obtained by using the evaluation value E (φ) weighted based on the color matching functions x (λ), y (λ), z (λ). ) Is evaluated, it is possible to obtain the ink amount set φ that can achieve visually sufficient accuracy.

  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. 18 schematically shows the printing method of the printer 20 of this embodiment. In addition, in order to obtain a spectral printing model including uniform color inks, each uniform color ink may be added as a primary color to the following model. 18, 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. ink amount set ψ described above _{(d c, d m, d} y, d k, d lc, d lm) is controlled to an amount specified by performed based on the print control data CD a. The ink droplets ejected by the nozzles 21a, 21a,... Become fine dots on the printing paper, and an ink amount set ψ (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 ψ which may 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 RDB obtained by actually printing color patches 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 ψ (d _c , d) is accurately obtained by performing prediction based on the cell division Yule-Nielsen spectral Neugebauer model using the spectral reflectance database RDB. _m , d _y , d _k , d _lc , d _lm ), and the spectral reflectance R (λ) when printing is predicted.

FIG. 19 shows the spectral reflectance database RDB. As shown in the figure, the spectral reflectance database RDB is an ink amount set ψ (d (d) in a plurality of lattice points in the ink amount space (in this embodiment, it is six-dimensional, but only the CM plane is shown for simplification of the drawing). _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 RDB 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 by the cell division Yule-Nielsen spectral Neugebauer model using the spectral reflectance database RDB will be described.

  The RPM P3a2 executes prediction based on the cell division Yule-Nielsen spectral Neugebauer model using the spectral reflectance database RDB 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 ψ are set as printing conditions. For example, when prediction is performed using glossy paper as a printing paper, a spectral reflectance database RDB created by printing color patches on glossy paper is set.

When it is set in the spectral reflectance database RDB, ink amount sets input from ICM P3a1 [psi 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 division 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).

FIG. 20 is a diagram showing 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 (4).

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。前記の（５ａ）式および（５ｂ）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 (4) can be rewritten as the following equation (5a) or (5b).

Here, n is a predetermined coefficient of 1 or more, and can be set to n = 10, for example. The above equations (5a) and (5b) 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-mentioned Yule-Nielsen Spectral Neugebauer Model into a plurality of cells. is there.

FIG. 21A 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. Note 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 RDB. That is, the spectral reflectance R (λ) of each lattice point can be obtained by referring to the above-described spectral reflectance database RDB. Therefore, the spectral reflectances R (λ) ₀₀ , R (λ) ₁₀ , R (λ) ₂₀ ... R (λ) ₃₃ of each lattice point can be acquired from the spectral reflectance database RDB.

In fact, performs six-dimensional ink amount space of even the cell division CMYKlclm In this embodiment, the ink amount sets [psi (d _c coordinates also the six-dimensional lattice _{points, d m, d y, d} k, d lc , D _lm ). Then, the ink amount set ψ of each grid point _{(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 RDB (for example, (From glossy paper).

FIG. 21 (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.

ここで、（６）式におけるインク被覆率ｆ_c，ｆ_mは図２１（Ｂ）のグラフで与えられる値である。また、セルＣ５を囲む４つの格子点に対応する分光反射率Ｒ（λ）₁₁，（λ）₁₂，（λ）₂₁，（λ）₂₂は分光反射率データベースＲＤＢを参照することにより取得することができる。これにより、（６）式の右辺を構成するすべての値を確定することができ、その計算結果として任意のインク量セットψ（ｄ_c，ｄ_m）にて印刷を行った場合の予測分光反射率Ｒ_s（λ）を算出することができる。波長λを可視波長域にて順次シフトさせていくことにより、可視波長域における予測分光反射率Ｒ_s（λ）を得ることができる。インク量空間を複数のセルに分割すれば、分割しない場合に比べて予測分光反射率Ｒ_s（λ）をより精度良く算出することができる。以上のようにして、ＲＰＭ Ｐ３ａ２がＩＣＭ Ｐ３ａ１の要請に応じて予測分光反射率Ｒ_s（λ）を予測することができる。 FIG. 21C 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. The calculation method is shown. The spectral reflectance R (λ) when printing is performed with the ink amount set (d _c , d _m ) is given by the following equation (6).

Here, the ink coverages f _c and f _m in the equation (6) are values given in 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 RDB. Can do. As a result, all values constituting the right side of the equation (6) can be determined, and the predicted spectral reflection when printing is performed with an arbitrary ink amount set ψ (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 wavelength 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, the RPM P3a2 can predict the predicted spectral reflectance R _s (λ) according to the request of the ICM P3a1.

前記の（７）式においては、ターゲットＴＧから得られたターゲット分光反射率Ｒ_t（λ）との相関が高い等色関数ｘ（λ），ｙ（λ），ｚ（λ）ほど線形結合の際の重みが大きくなるようにされている。以上のようにして得られた重み関数ｗ（λ）においては、ターゲットＴＧのターゲット分光反射率Ｒ_t（λ）が大きい波長域についての重みを強調することができる。従って、各光源下での反射光の分光エネルギーのスペクトルが強くなりがちな波長域を重視した評価値Ｅ（φ）を得ることができる。すなわち、特にターゲットＴＧのターゲット分光反射率Ｒ_t（λ）が大きい波長域については、ターゲットＴＧのターゲット分光反射率Ｒ_t（λ）と予測分光反射率Ｒ_s（λ）とのずれを許容しないようなインク量セットφの最適解を得ることができる。むろん、重み関数ｗ（λ）は各等色関数ｘ（λ），ｙ（λ），ｚ（λ）に由来しているため、人間の知覚に適合した評価値Ｅ（φ）を得ることができる。 5. Modification 5-1: Modification 1
FIG. 22 schematically shows the weighting function w (λ) set by the ECM P3a3 in the modification. In the figure, the target spectral reflectance R _t (λ) obtained from the target TG is shown, and the target spectral reflectance R _t (λ) and the color matching functions x (λ), y (λ), Correlation coefficients c _x , c _y and c _z with z (λ) are calculated by ECM P3a3. Then, the weighting function w (λ) according to this modification is calculated by the following equation (7).

In the above equation (7), the color combination functions x (λ), y (λ), z (λ) having a higher correlation with the target spectral reflectance R _t (λ) obtained from the target TG are linearly coupled. The weight at the time is made large. In the weight function w (λ) obtained as described above, it is possible to emphasize the weight for the wavelength region where the target spectral reflectance R _t (λ) of the target TG is large. Therefore, it is possible to obtain an evaluation value E (φ) that emphasizes the wavelength range where the spectrum of the spectral energy of the reflected light under each light source tends to be strong. That is, especially in the wavelength region where the target spectral reflectance R _t (λ) of the target TG is large, a deviation between the target spectral reflectance R _t (λ) of the target TG and the predicted spectral reflectance R _s (λ) is not allowed. Such an optimal solution of the ink amount set φ can be obtained. Of course, since the weight function w (λ) is derived from each color matching function x (λ), y (λ), z (λ), an evaluation value E (φ) suitable for human perception can be obtained. it can.

5-2: Modification 2
FIG. 23 schematically shows the weighting function w (λ) set by the ECM P3a3 in another modification. In the figure, the target spectral reflectance R _t (λ) obtained from the target TG is applied as it is as the weighting function w (λ). By doing so, in particular a deviation of the spectral reflectance of the target TG for target spectral reflectance R _t (λ) is larger wavelength range of the target TG R and (lambda) and the target spectral reflectance R _t (λ) An optimum solution of the ink amount set φ that is not allowed can be obtained.

5-3: Modification 3
FIG. 24 schematically shows the weighting function w (λ) set by the ECM P3a3 in another modification. 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, these spectral energies P _D50 (λ), P _D55 (λ), P _D65 (λ), P _A (λ), and P _F11 (λ) are linearly combined by the following equation (8). Thus, the weight function w (λ) is calculated.

In the above equation (8), w _{1 to} w ₅ are weighting factors for setting the weight for each light source. Thus, the weighting function w (λ) derived from the spectral energy distributions P _D50 (λ), P _D55 (λ), P _D65 (λ), P _A (λ), and P _F11 (λ) of the light source is set. As a result, it is possible to obtain an evaluation value E (φ) that places importance on the wavelength range in which the spectrum of the spectral energy of the reflected light under each light source tends to be strong. It is also possible to adjust the weighting coefficients w ₁ to w _5. For example, w ₁ = w ₂ = w ₃ = w ₄ = w ₅ may be used to ensure a good balance of color reproducibility for all light sources, and w may be used if importance is attached to color reproducibility for artificial light sources. ₁ , w ₂ , w ₃ <w ₄ , w ₅ may be set.

5-4: Modification 4
FIG. 25 shows a UI screen displayed on the display 40 in the modified example. In the figure, a graph of a plurality of target spectral reflectances R _t (λ) is displayed on the UI screen. By displaying such a UI screen, instead of the user measuring the target spectral reflectance R _t (λ) of the target TG in step S140, a graph of a desired waveform is displayed on the target spectral reflectance R _t ( λ) can be selected. In this way, the target spectral reflectance R _t (λ) can be set without actually measuring the spectral reflectance. Of course, the waveform of the graph may be directly editable by the user. For example, if editing the target spectral reflectances R _t (λ) of the target in the development of new of the object surface, without actually prototyping the object surface, the target spectral reflectance targeted R _t A sample chart SC having (λ) can be printed by the printer 20.

前記の（２）式において、ｗ₁〜ｗ₅は各光源の重みを設定する重み係数であり、上述した変形例３の重み係数ｗ₁〜ｗ₅とほぼ同様の性質を有する。ここでも全光源における色の再現性をバランスよく確保したい場合にはｗ₁＝ｗ₂＝ｗ₃＝ｗ₄＝ｗ₅とすればよいし、人工光源における色の再現性を重視したい場合にはｗ₁，ｗ₂，ｗ₃＜ｗ₄，ｗ₅とすればよい。 5-5: Modification 5
FIG. 26 schematically illustrates the evaluation value (φ) according to the modification. In the figure, the color values (target color values) when the five types of light sources are irradiated to the target spectral reflectance R _t (λ) of the target TG are calculated by the above-described equation (1) and FIG. On the other hand, the color values (predicted color values) when the five types of light sources are applied to the predicted spectral reflectance R _s (λ) predicted by the RPM P3a2 are also expressed by the above-described equation (1) (R _t (λ)). R _s (λ) is used) and calculated according to FIG. Then, the color difference ΔE (ΔE ₂₀₀₀ ) between the target color value and the predicted color value for each light source is calculated based on the color difference formula of CIE DE2000. Then, the color difference ΔE for each light source is set to ΔE _D50 , ΔE _D55 , ΔE _D65 , ΔE _A , ΔE _F11, and the evaluation value E (φ) is calculated by the following equation (9).

In the above equation (2), w _{1 to} w ₅ are weighting factors for setting the weights of the respective light sources, and have substantially the same properties as the weighting factors w _{1 to} w _{5 of} Modification 3 described above. Here too, w ₁ = w ₂ = w ₃ = w ₄ = w ₅ should be used to ensure a good balance of color reproducibility for all light sources, and when color reproducibility for artificial light sources should be emphasized. It may be set as w ₁ , w ₂ , w ₃ <w ₄ , w ₅ .

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 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 graph of the spectral reflectance distribution of a cyan color ink set. It is a graph of the spectral reflectance distribution of a magenta color ink set. It is a graph of the spectral reflectance distribution of a yellow color ink set. 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 which shows the weight function concerning a modification. It is a schematic diagram which shows the weight function concerning a modification. It is a schematic diagram which shows the weight function concerning a modification. It is a figure which shows UI screen concerning a modification. It is a schematic diagram which shows the evaluation value 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, P3 ... PDV, P3a1 ... ICM, P3a2 ... RPM, P3a3 ... ECM, P3a4 ... LOM, P4 ... MDV, P5 ... DDV.

Claims (8)

A printing control apparatus that causes the printing apparatus to perform printing based on a color material amount set that is a combination of the amounts of the color materials when causing the printing apparatus to perform printing for attaching a plurality of color materials to a recording medium,
The plurality of color materials includes at least one set of color matching color materials having spectral reflectance characteristics different from each other while having substantially the same color value under a predetermined light source,
The print control device includes:
Receiving means for receiving an instruction of a spectral reflectance to be printed or a color value to be printed;
Spectral reflectance printing control means for causing the printing apparatus to execute printing based on the color material amount set determined based on the spectral reflectance when the spectral reflectance is received;
Color value printing control means for causing the printing apparatus to execute printing based on the color material amount set determined based on the color value when receiving a color value;
A printing control apparatus comprising:   2. The print control according to claim 1, wherein the color value print control unit executes printing using each of the equal color materials having substantially the same color value at substantially the same ratio over one printing. apparatus.   3. The printing according to claim 2, wherein the color value printing control unit executes printing using the equal color material having substantially the same color value according to a remaining amount or in substantially the same amount. Control device.   The print control apparatus according to claim 1, wherein the reception unit receives the spectral reflectance or the color value specified by the print data by analyzing the received print data.   The spectral reflectance printing control means records the spectral reflectance that approximates the instructed spectral reflectance based on an evaluation value that evaluates the closeness to the target spectral reflectance while taking into account different weights depending on wavelengths. The print control apparatus according to claim 1, wherein the color material amount set shown on the medium is predicted, and the printing apparatus is caused to execute printing based on the predicted ink amount set. When the printing apparatus executes printing for attaching a plurality of color materials to a recording medium, a color material amount set that is a combination of the color material amounts is specified, and printing based on the color material amount set is performed on the printing apparatus. A printing control device,
The plurality of color materials includes at least one set of color matching color materials having spectral reflectance characteristics different from each other while having substantially the same color value under a predetermined light source,
The print control device includes:
Target spectral reflectance acquisition means for acquiring the spectral reflectance of the target as the target spectral reflectance;
Based on the evaluation value that evaluates the closeness to the target spectral reflectance while taking into account different weights depending on the wavelength, the color material amount set indicating the spectral reflectance that approximates the target spectral reflectance on the recording medium. Printing control means for predicting and designating the predicted ink amount set to the printing apparatus;
A printing control apparatus comprising: A printing apparatus that executes printing for attaching a plurality of color materials to a recording medium and printing based on a color material amount set that is a combination of the color material amounts are designated to the printing apparatus, and based on the color material amount set A printing system comprising a print control device for executing printing,
The plurality of color materials includes at least one set of color matching color materials having spectral reflectance characteristics different from each other while having substantially the same color value under a predetermined light source,
The print control device includes:
Receiving means for receiving an instruction of a spectral reflectance to be printed or a color value to be printed;
Spectral reflectance printing control means for causing the printing apparatus to execute printing based on the color material amount set determined based on the spectral reflectance when the spectral reflectance is received;
Color value printing control means for causing the printing apparatus to execute printing based on the color material amount set determined based on the color value when receiving a color value;
With
The printing apparatus includes:
A printing system comprising printing effective means for executing printing based on the color material amount set predicted by the printing control means. In order to cause a computer to implement a function of causing a printing apparatus to execute printing based on a color material amount set that is a combination of the amounts of color materials when causing a printing apparatus to execute printing that attaches a plurality of color materials to a recording medium. Printing control program
The plurality of color materials includes at least one set of color matching color materials having spectral reflectance characteristics different from each other while having substantially the same color value under a predetermined light source,
The print control program is
A reception function for receiving an instruction of a spectral reflectance to be printed or a color value to be printed;
A spectral reflectance printing control function for causing the printing apparatus to perform printing based on the color material amount set determined based on the spectral reflectance when the spectral reflectance is received;
A color value printing control function for causing the printing apparatus to execute printing based on the color material amount set determined based on the color value when a color value is received;
A print control program for causing a computer to realize the above.

Images