JP5314623B2 - Printing color reproduction condition evaluation method and selection method thereof, color conversion method and apparatus and program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaluation method for a print color reproduction condition, with which whether color reproducibility of a printed matter is high or low can be easily and appropriately evaluated among a large number of condition combinations, and to provide a selection method therefor, and a color conversion method. <P>SOLUTION: Each of designation groups (a group of media 36, a group of laminate films 40 and a group of light sources LS) to be evaluated is designated, all print color reproduction conditions selectable from among the designation groups are set as candidate conditions, and print profiles are generated, respectively, based on first spectral data of a printed matter 38 obtained by printing on the media 36 corresponding to the candidate conditions, second spectral data of the laminate films 40 and third spectral data of the light sources LS. Reproduction colors corresponding to pixels of image data are predicted based on the generated print profiles corresponding to the candidate conditions, whether colors can be reproduced on the pixels is discriminated based on the predicted reproduction colors and target colors in printing, and condition evaluation information is generated for evaluating the candidate conditions based on a result of the reproduction discrimination. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention evaluates print color reproduction conditions for predicting and evaluating color reproducibility when applying print color reproduction conditions including information on media, a protective film, and an observation light source to image data representing a color image. The present invention relates to a method, a selection method thereof, a color conversion method, an apparatus thereof, and a program.

  With the rapid progress of ink jet technology in recent years, color large format printing that achieves both high speed and high image quality by an ink jet printer is becoming possible. This printing press is used not only for personal and home use, but also recently in a wide range of fields, particularly in commercial use. By using this printing machine, for example, it is possible to print not only on storefront POP (Point of Purchase) and wall posters, but also on large-size media such as outdoor advertisements / signboards, roll media, and thick hard media. .

  In order to meet such diverse commercial demands, there are a wide variety of print media (hereinafter also referred to as “media”) used for printing. For example, papers such as synthetic paper, cardboard, and aluminum vapor-deposited paper, resins such as vinyl chloride and PET, and tarpaulins in which a synthetic resin film is bonded to both sides of a fiber fabric are used.

  Since advertisement printing is expected to have an effect of inviting consumers to purchase through visual perception, the color finish of printed matter (printed print medium) is particularly important. Conventionally, many color matching techniques such as an ICC (International Color Consortium) profile creation method, a specified color adjustment method, and an optimum printing condition / observation condition selection method have been disclosed as color management means for printed matter. .

  For example, Patent Document 1 discloses that any one of a plurality of printing apparatuses based on a color gamut to be expressed by print job data and a printing profile of the printing apparatus based on the reproduction degree of the color gamut. An apparatus and a method for selecting a printing apparatus are disclosed (see [0004], [0036] and FIG. 15 of Patent Document 1).

  Further, Patent Document 2 discloses a system that configures an input / output device profile by combining a plurality of profiles having different data attributes. For example, a parameter relating to paper (see [0047] in Patent Document 2 and FIG. 4) is set as a print output condition profile, and a parameter relating to an observation light source (see [0049] in FIG. 6) is set as an observation condition profile. As a result, image data can be easily processed according to the type of observation light source and media, and color reproduction with high accuracy can be performed (see [0086]).

JP 2003-266891 A JP-A-7-154623

  The present invention has been made in connection with the technical idea disclosed in the above-mentioned Patent Documents 1 and 2, and it is easy and appropriate to improve the color reproducibility of printed matter out of a huge number of condition combinations. It is an object of the present invention to provide an evaluation method of print color reproduction conditions that can be evaluated, a selection method thereof, a color conversion method, an apparatus thereof, and a program.

  The print color reproduction condition evaluation method according to the present invention predicts color reproducibility when applying print color reproduction conditions including information on media, a protective film, and an observation light source to image data representing a color image. It is related to the evaluation method.

  And a designation step for designating a media group, a protective film group, and an observation light source group to be evaluated, and all print color reproductions that can be selected from the designated media group, the protective film group, and the observation light source group. A setting step for setting a condition as a candidate condition, an optical property value of a printed material obtained by printing on each medium corresponding to each of the set candidate conditions, an optical property value of each protective film, and a spectral value of each observation light source A profile generation step for generating each print profile based on the distribution; a prediction step for predicting a reproduction color corresponding to the pixel of the image data based on each print profile corresponding to each of the generated candidate conditions; A discrimination step of discriminating whether or not the color can be reproduced on the pixel based on the predicted reproduction color and the target color at the time of printing; Characterized in that it comprises a condition evaluation information generating step of generating a condition evaluation information for evaluating each said candidate condition based on current availability.

  In this way, all print color reproduction conditions that can be selected from the media group, the protective film group, and the observation light source group that are designated as evaluation targets are set as candidate conditions, and color reproduction on each pixel of the image data is performed. Since the condition evaluation information for evaluating each of the candidate conditions is generated based on whether or not the reproduction is possible, the conditions can be efficiently narrowed down within the range of the evaluation target designated in advance by the operator. This is possible, and it is no longer necessary to evaluate the color reproducibility of the printed material by forming a printed material for each different printing color reproduction condition, and it is easy to improve the color reproducibility of the printed material from a large number of condition combinations. And can be evaluated appropriately.

  Further, it is preferable that the determination step determines whether or not the color can be reproduced on the pixel depending on whether or not the target color belongs to a reproduction gamut at the time of printing.

  Furthermore, it is preferable that the condition evaluation information is a ratio of the number of pixels corresponding to the color determined to be reproducible with respect to the number of pixels of the image data. Thereby, the color reproduction rate in the whole image data can be easily grasped.

  Further, the condition evaluation information is evaluation image data in which the pixel value of each pixel is determined so that the reproducibility of the color corresponding to each pixel of the color image can be visualized and determined. It is preferable. Thereby, by visualizing the evaluation image data, it is possible to grasp at a glance whether the color reproducibility of the image data is good or bad.

  Furthermore, the image data for evaluation visualizes the reproducibility of the color corresponding to each pixel of the color image under the print color reproduction condition when the protective film is not covered under the print color reproduction condition. The image data is preferably image data in which the pixel value of each pixel is determined so as to be discriminated. Thereby, by visualizing the image data for evaluation, it is possible to grasp at a glance the degree of influence on the color reproducibility when the protective film is coated on the printed matter.

  It is preferable that the method further includes a step of displaying the evaluation image data.

  Furthermore, it is preferable that the method further includes a step of setting a predetermined image area in the color image, and whether or not the reproduction is possible is determined on each pixel in the set image area.

  Furthermore, it is preferable to further include a step of setting a predetermined color area in the color space coordinates, and whether or not the reproduction is possible is determined on each pixel corresponding to the color in the set color area.

  Further, the condition evaluation information is an evaluation obtained by weighting a numerical value determined based on the result of the reproducibility according to an image area of the color image and adding the weight for each pixel of the color image. It is preferably a value. Thereby, the weight of the evaluation value according to the image area can be provided.

  Further, the condition evaluation information is an evaluation obtained by weighting a numerical value determined based on the reproducibility result according to a color area of a color space coordinate and adding the weight for each pixel of the color image. It is preferably a value. Thereby, the weight of the evaluation value according to the color region can be provided.

  Furthermore, the color value of the black point related to the profile when the protective film is coated under the printing color reproduction condition is matched with the color value of the black point related to the profile when the protective film is not coated under the printing color reproduction condition. It is preferable to further include a step of correcting the black point. This makes it possible to substantially match the color reproducibility of the shadow area, regardless of whether or not the protective film is covered.

  Furthermore, it is preferable to further comprise a step of selecting whether or not to perform the black point correction.

  Furthermore, the method further includes a step of generating new image data by thinning out pixels of the image data, and applying the print color reproduction condition to the image data by using the new image data instead of the image data. It is preferable to predict and evaluate color reproducibility in some cases. Thereby, the time required for printing color reproduction evaluation can be shortened.

  Further, when the medium is a reflective medium, the optical physical property value of the printed matter related to the medium is a spectral reflectance, and the optical physical property value of the protective film is an intrinsic reflectance or scattering for each light wavelength of the protective film. Two independent optical properties of the coefficient and the absorption coefficient are preferred.

  Furthermore, when the medium is a transmissive medium, the optical property value of the printed matter and the protective film relating to the medium is preferably a spectral transmittance.

  The method for selecting a print color reproduction condition according to the present invention includes a step of selecting one print color reproduction condition based on the obtained evaluation result using any one of the above-described print color reproduction condition evaluation methods. It is characterized by.

  The color conversion method according to the present invention includes the step of color-converting the image data using a print profile corresponding to the selected one print color reproduction condition using the above-described print color reproduction condition selection method. It is characterized by providing.

  The color conversion apparatus according to the present invention includes a condition selection unit that selects the one print color reproduction condition using the above-described method for selecting a print color reproduction condition, and the one print color reproduction condition that is selected by the condition selection unit. And a color conversion processing unit for color-converting the image data using a print profile corresponding to the above.

  The program according to the present invention allows a computer to predict and evaluate color reproducibility when applying print color reproduction conditions including information on media, a protective film, and an observation light source to image data representing a color image. , Means for designating a media group, a protective film group, and an observation light source group to be evaluated; candidates for all print color reproduction conditions that can be selected from the designated media group, the protective film group, and the observation light source group Based on the means for setting as a condition, the optical property value of the printed matter obtained by printing on each medium corresponding to each of the set candidate conditions, the optical property value of each protective film, and the spectral distribution of each observation light source Means for generating each print profile, and reproduction corresponding to a pixel of the image data based on each print profile corresponding to each generated candidate condition Means for predicting, means for determining whether or not a color can be reproduced on the pixel based on the predicted reproduction color and a target color at the time of printing, and each candidate condition based on the determined reproduction possibility or not It is made to function as a means to produce | generate the condition evaluation information for evaluating.

  According to the printing color reproduction condition evaluation method, the selection method, the color conversion method, the apparatus, and the program according to the present invention, it is possible to select from the media group, the protective film group, and the observation light source group designated as the evaluation target. All print color reproduction conditions are set as candidate conditions, whether color reproduction is possible on each pixel of image data is determined, and condition evaluation information for evaluating each candidate condition is generated based on the reproduction possibility As a result, conditions can be efficiently narrowed down within the range of the evaluation target designated in advance by the operator, and a printed matter is formed for each different printing color reproduction condition to evaluate the color reproducibility of the printed matter. This eliminates the need for this, and makes it possible to easily and appropriately evaluate whether the color reproducibility of the printed material is good or bad from a huge number of condition combinations.

1 is an explanatory perspective view of a printing system in which a color conversion apparatus according to an embodiment is incorporated. It is a schematic front view of the color chart shown in FIG. It is a functional block diagram of the color conversion apparatus shown in FIG. FIG. 4 is a functional block diagram of a profile generation unit shown in FIG. 3. FIG. 4 is a functional block diagram of a colorimetric value calculation unit shown in FIG. 3. FIG. 4 is a functional block diagram of a color reproduction simulation unit shown in FIG. 3. It is a figure which shows an example of the screen which sets the evaluation variable of printing color reproduction conditions. It is a figure which shows an example of the screen which displays the evaluation result of the color reproducibility simulation with respect to each candidate condition. It is a flowchart for obtaining the printed matter with a protective film appropriately color-adjusted using the printing system according to the present embodiment. 10A to 10C are diagrams illustrating a gamut conversion process by black point correction. It is a flowchart regarding the method of evaluating each candidate condition based on condition evaluation information. 12A to 12C are diagrams illustrating display examples of the evaluation image data generated by the color reproduction simulation unit of FIG. It is a schematic sectional drawing of the measurement sample produced in order to estimate the optical physical-property value of a laminate film.

  Hereinafter, preferred embodiments of the method for evaluating a printing color reproduction condition according to the present invention in relation to a color conversion apparatus and a printing system for carrying out the method will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an explanatory perspective view of a printing system 10 in which an image processing apparatus 16 as a color conversion apparatus according to this embodiment is incorporated.

  The printing system 10 basically includes a LAN 12, an editing device 14, an image processing device 16 as a color conversion device, a printing machine 18, a lamination processing device 20, and a colorimeter 22.

  The LAN 12 is a network constructed based on a communication standard such as Ethernet (registered trademark). The editing device 14, the image processing device 16, and the database DB are connected to each other by wire or wireless via the LAN 12.

  The editing device 14 can freely edit the arrangement of color images composed of characters, figures, patterns, photographs, etc. for each page, and an electronic manuscript in a page description language (hereinafter referred to as PDL), for example, four colors ( CMYK) and 3-bit (RGB) color channels are generated.

  Here, PDL is a language that describes image information such as text, graphics, and other format information, position information, and color information (including density information) within a “page” that is an output unit for printing and display. . For example, PDF (abbreviation of Portable Document Format, specified in ISO 32000-1: 2008), Adobe Systems PostScript (registered trademark), XPS (XML Paper Specification), and the like are known.

  Further, a color scanner (not shown) is connected to the editing device 14, and the color scanner optically reads a color document set at a predetermined position, so that color image data serving as a component of the electronic document is obtained. Can be obtained.

  As will be described later, the image processing device 16 expands an electronic document by PDL into a bitmap format (a type of raster image), performs desired image processing, for example, color conversion processing, image scaling processing, arrangement processing, and the like. Each function has a function of converting to a printing signal suitable for the printing method of the printing machine 18 and transmitting the printing signal to the printing machine 18.

  The image processing device 16 includes a main body 24 having a CPU, a memory, and the like, a display device 26 that displays a color image, and an input device 28 (keyboard 30 and mouse 32) as an input unit. Further, a portable memory 34 and a colorimeter 22 that can freely record and erase electronic data are connected to the image processing device 16.

  The printing machine 18 is an ink jet system that forms a color image by combining standard inks composed of C, M, Y, and K (process colors) and optional inks such as light colors such as LC and LM and W (white). Printing device. The printing machine 18 performs ejection control of ink of each color based on a print signal received from the outside (for example, the image processing device 16), so that a medium 36 (in FIG. 1, a roll-shaped unprinted print). A color image is printed on the medium 36) to form a printed matter 38 (including a color chart 38c which is a kind of the printed matter 38).

  The laminating apparatus 20 heats and pressurizes using a heating roller (not shown) in a state where a laminate film 40 as a protective film is stuck on the image forming surface of the printed matter 38 on the back surface as necessary. By performing the above, a printed matter 42 with a protective film in which the image forming surface of the printed matter 38 is protected is formed.

  As the base material of the medium 36, paper such as synthetic paper, cardboard, and aluminum vapor-deposited paper, resin such as vinyl chloride and PET, tarpaulin, and the like can be used. The protective film is not limited to the laminate film 40, and a liquid, varnish, transparent ink, clear toner, a protective plate such as an acrylic plate, or the like can be used.

The colorimeter 22 measures the color value of the measurement object. Here, the color value is not only the tristimulus value XYZ, the coordinate value L ^* a ^* b ^{* of} the uniform color space, etc., but also the distribution of optical property values with respect to the wavelength (hereinafter referred to as “spectral data”), for example, spectral Radiation distribution (spectral distribution), spectral sensitivity distribution, spectral reflectance or spectral transmittance is included. Further, a color value obtained by color measurement using the colorimeter 22 may be referred to as “color measurement value”.

  In FIG. 1, the printing system 10 is installed under the light source LS. The spectral distribution of the light source LS as the observation light source may differ depending on the posting location of the printed matter 42 with the protective film (or the printed matter 38).

  FIG. 2 is a schematic front view of the color chart 38c shown in FIG.

  The color chart 38c includes 100 color patches 44 of substantially the same shape that are printed on the medium 36, and a numeric string 46 and alphabet characters that specify the arrangement positions of the color patches 44 in the row and column directions. A column 48 and printing information 50 including information for identifying the printing conditions of the color chart 38c are configured.

  In each color patch 44, ten color patches 44 are arranged without gaps in the vertical direction, and ten color patches 44 are arranged in the horizontal direction with gaps of a predetermined interval. The color of each color patch 44 is set to a predetermined value in a range of signal levels of CMYK values (0% to 100% as a percentage, 0 to 255 in the case of 8-bit gradation).

  The numeric string 46 is provided as a character string of (01) to (10) in order from the top so as to correspond to the position on the left side of each color patch 44. On the other hand, the alphabetic character string 48 is provided as a character string of (A) to (J) in order from the left so as to correspond to the position above each color patch 44.

  The print information 50 is printed with the model of the printing machine 18, serial number or registered name, print mode to be described later, type of media 36, print date and time, and the like.

  FIG. 3 is a functional block diagram of the image processing apparatus 16 as a color conversion apparatus according to the present embodiment. The electronic document is supplied in the direction of a white solid arrow, the image data for the color chart 38c is supplied in the direction of a white broken arrow, and the other various data is supplied in the direction of a solid line arrow.

  The main body 24 of the image processing apparatus 16 has an I / F 52 for inputting an electronic document supplied from the editing device 14 side, and an RIP 54 for expanding the PDL format of the electronic document supplied via the I / F 52 into a bitmap format. (Raster imaging processor), a color conversion processing unit 56 that performs predetermined color conversion processing on the CMYK values (or RGB values) of the electronic document developed by the RIP 54 to obtain image data of new CMYK values, A printer driver 58 that converts new CMYK value image data obtained by color conversion by the color conversion processing unit 56 into a print signal (ink ejection control data) suitable for the printer 18, and the printer driver 58 And an I / F 60 for outputting the print signal converted by the printer 18 to the printer 18 side.

  Further, the main body 24 prints a profile generation unit 62 that generates a profile for each printing machine 18, a black point correction processing unit 64 that performs black point correction described later on a color conversion LUT included in the profile, and a color chart 38c. An image data generation unit 66 for generating the image data, an optical property value estimation unit 68 for estimating the optical property value of the laminate film 40, and a color reproduction simulation unit for simulating color reproducibility using the image data of the electronic document 70, an I / F 72 that enables connection to the display device 26, an I / F 74 that enables connection to the input device 28 (keyboard 30 and mouse 32), and the colorimeter 22 can be connected. And an I / F 78 that enables connection to the portable memory 34.

  Furthermore, the main body 24 includes a storage unit 80 that stores various data supplied from each internal component, or supplies various stored data to each component. The storage unit 80 includes a RIP 54, a color conversion processing unit 56, a profile generation unit 62, a black spot correction processing unit 64, an image data generation unit 66, an optical property value estimation unit 68, and a color reproduction simulation unit 70. , I / F 72, I / F 74, I / F 76, and I / F 78, respectively.

  The color conversion processing unit 56 includes a target profile processing unit 82 that converts device-dependent data into device-independent data, and a print profile processing unit 84 that converts device-independent data into device-dependent data. Here, the device-dependent data is data defined by CMYK values, RGB values, etc. for appropriately driving various devices. The device-independent data is data defined in a color system such as HSV (Hue-Saturation-Value), HLS (Hue-Lightness-Saturation), CIELAB, CIEUV, and XYZ.

  The RIP 54 can perform various image processing such as image enlargement / reduction processing corresponding to the resolution of the printing machine 18 and rotation / reversal processing corresponding to the printing format when the electronic original is converted into a bitmap format. .

  Further, the printer driver 58 creates ink ejection control data corresponding to each ink color (CMYK, LC, LM, or W) from the CMYK values. This ink ejection control data is associated with the ink ejection operation (ON / OFF, ink dot diameter size, etc.) of the printing machine 18 according to the data definition specific to the printing machine 18. At that time, conversion from an 8-bit multi-tone image to a low-tone image such as a binary image is required, but a known algorithm such as a dither matrix method or an error diffusion method can be used.

  Furthermore, the target profile processing unit 82 or the print profile processing unit 84 can correct the profile according to the printing mode of the printing machine 18. Here, the print mode refers to the number of nozzles of the print head, the ink ejection timing (one-way / bidirectional) during scanning of the print head, the number of passes, the number of mounted ink colors and their types, and the algorithm for creating ink ejection control data. This refers to various settings related to printing.

  Further, a control unit (not shown) constituted by a CPU or the like performs all the control related to the image processing. That is, not only control of each component in the main body 24 (for example, data read / write of the storage unit 80) but also control of acquiring color measurement data from the colorimeter 22 via the I / F 76, and the like.

  The image processing apparatus 16 according to the present embodiment is configured as described above, and each of the image processing functions described above can be realized by using an application program that operates on a basic program (operating system).

  FIG. 4 is a functional block diagram of the profile generation unit 62 shown in FIG.

  The profile generation unit 62 basically includes a data selection unit 86, a colorimetric value calculation unit 88, and an LUT generation unit 90.

  The data selection unit 86 reads the profile based on the setting data 100, the spectral data group 102 of the medium, the spectral data group 104 of the laminate film, and the spectral data group 106 of the observation light source read from the storage unit 80. Media spectral data (hereinafter referred to as first spectral data 112), lamination film spectral data (hereinafter referred to as second spectral data 114), and observation light source spectral data (hereinafter referred to as third spectral data) under the generation conditions. Spectral data 116) is selected. Here, the setting data 100 is the type of the media 36, the laminate film 40, and the light source LS set by the operator, and is setting data related to profile generation conditions.

  The colorimetric value calculation unit 88 calculates the colorimetric value data 120 under the profile generation condition based on the first, second, and third spectral data 112, 114, and 116 selected by the data selection unit 86.

  The LUT generation unit 90 performs color conversion under profile generation conditions based on the colorimetric value data 120 calculated by the colorimetric value calculation unit 88 and the CMYK value data 122 corresponding to each color patch 44 (see FIG. 2). An LUT 124 is generated.

In this embodiment, spectral data for 100 color patches 44 (patch numbers are 0 to 99) is provided, and 41 points of data with light wavelengths of λ ₁ to λ ₄₁ are included. For example, λ ₁ = 400 nm,..., Λ ₄₁ = 800 nm can be set at 10 nm intervals.

  FIG. 5 is a functional block diagram of the colorimetric value calculation unit 88 shown in FIG.

  The colorimetric value calculation unit 88 basically includes a reflectance / transmittance prediction unit 88a and a Lab calculation unit 88b.

  The reflectance / transmittance prediction unit 88a applies a mathematical model corresponding to the type of the medium 36 based on the first and second spectral data 112 and 114 supplied from the data selection unit 86, and the printed matter with the protective film. 42 spectral reflectance or spectral transmittance (hereinafter referred to as fourth spectral data 118) is predicted.

  Here, when the medium 36 is a reflective medium, the first spectral data 112 is the spectral reflectance of the medium 36, and the second spectral data 114 is the intrinsic reflectance and scattering for each light wavelength of the laminate film 40. Coefficient, absorption coefficient (optical property value). When the medium 36 is a transmissive medium, the first spectral data 112 is the spectral transmittance of the medium 36, and the second spectral data 114 is the spectral transmittance (optical physical property value) of the laminate film 40. .

  The Lab calculation unit 88b includes the third spectral data 116 supplied from the data selection unit 86, the fourth spectral data 118 predicted by the reflectance / transmittance prediction unit 88a, and a color matching function (standard) (not shown). Colorimetric value data 120 under the profile generation condition is calculated based on the spectral data taking into account the visual characteristics of the observer.

  FIG. 6 is a functional block diagram of the color reproduction simulation unit 70 of FIG.

The color reproduction simulation unit 70 includes an image enlargement / reduction processing unit 130 that performs enlargement processing or reduction processing on image data, and a target color that converts device-dependent data into device-independent data and calculates a target color corresponding to each pixel. Candidate conditions for setting candidate conditions from the calculation unit 132 and the media 36 group, the laminate film 40 group, and the light source LS group (hereinafter sometimes collectively referred to as “each designated group”) designated as evaluation targets. A setting unit 134, a profile generation unit 136 that generates a profile based on the first, second, and third spectral data 112, 114, and 116, and a reproduction color that corresponds to each pixel of the image data based on the print profile A reproduction color prediction unit 138 that predicts color reproduction, a reproducibility determination unit 140 that determines color reproducibility on each pixel, and a condition evaluation information described later A condition evaluation information generation unit 142 for generating an evaluation image data generating unit 144 for evaluating each candidate conditions, the device independent data (L ^* a ^* b ^* values) evaluation image data defined by And a display profile processing unit 146 that converts the device-dependent data (RGB values).

  FIG. 7 is a diagram illustrating an example of a screen for setting an evaluation variable for print color reproduction conditions.

  In the setting screen 150, the text box 152a and the button 152b displayed as [Open], the text box 154a and the button 154b displayed as [Open], and [Important color designation] are displayed in order from the top to the bottom. Button 156, two check boxes 158 and 160, three pull-down menus 162, 164 and 166, three buttons 168, 170 and 172 displayed as “Add”, and three displays Columns 174, 176, and 178, and buttons 180, 182, and 184 displaying [Confirm], [Delete], and [Delete All] are provided.

  A text box 152a and a button 152b located in the upper left part of the setting screen 150 are provided adjacent to each other in the left-right direction. "Print image" is displayed on the left side of the text box 152a. A text box 154a and a button 154b located in the upper right part of the setting screen 150 are provided adjacent to each other in the left-right direction. "Profile" is displayed on the left side of the text box 154a.

  In the check boxes 158 and 160 provided below the text boxes 152a and 154a, check marks can be added and deleted by clicking the mouse 32 (see FIG. 1). On the right side of the check boxes 158 and 160, “high saturation importance” and “shadow importance” are displayed, respectively.

  The pull-down menus 162, 164, and 166 located in the center of the setting screen 150 are arranged side by side in the left-right direction, and “PVC B”, “MAT C”, and “F8” are displayed in the columns. "Media", "laminate", and "observation light source" are respectively displayed above the pull-down menus 162, 164, and 166, and buttons 168, 170, and 172 are disposed below the pull-down menus 162, 164, and 166, respectively.

  Three display fields 174, 176, and 178 are provided further below the buttons 168, 170, and 172 and inside a frame 186 that displays “candidate condition list”. The display column 174 displays “PVC A” and “PVC B”, the display column 176 displays “MAT A”, “MAT B”, and “MAT C”, and the display column 178 displays “F8”. It is displayed.

  FIG. 8 is a diagram illustrating an example of a screen that displays the evaluation result of the color reproducibility simulation for each candidate condition.

  The setting screen 190 is provided with a display field 192 and a plurality of buttons 194 displayed as [Image display].

  The display column 192 is a column provided in a matrix of 9 rows and 5 columns, and displays an item column 196 corresponding to the first row from the top and a “media” corresponding to the first column from the left. Column 198, “laminate” display column 200 corresponding to the second column, “observation light source” display column 202 corresponding to the third column, “in gamut” display column 204 corresponding to the fourth column, The column includes an “important color accuracy” display column 206 corresponding to the fifth column.

  FIG. 9 is a flowchart for obtaining a protective material-coated printed matter 42 of an appropriate color using the printing system 10 according to the present embodiment. Description will be made mainly with reference to FIG.

  First, the operator designates the media 36 group, the laminate film 40 group, and the light source LS group to be evaluated (step S1).

  The operator inputs each designated group using pull-down menus 162, 164, 166 and buttons 168, 170, 172 on the setting screen 150 shown in FIG. Here, an input method of the media 36 group will be described.

  The operator uses the pull-down menu 162 to select the type of media 36 to be added as a candidate condition from all the types of media 36 registered in advance. Then, the type name (“PVC B” in the example of FIG. 7) is displayed in the pull-down menu 162 field. In this state, when the operator presses the [Add] button 168, “PVC B” is added immediately below the lowermost row in the display field 174 below the operator. By repeating the same operation, the type of the media 36 can be added as appropriate.

  Further, the type of the laminate film 40 can be added to the display field 176 using the pull-down menu 164 and the button 170, and the type of the light source LS can be added to the display field 178 using the pull-down menu 166 and the button 172.

  Furthermore, when the operator selects any item in the display fields 174, 176, and 178 by clicking the mouse 32 (see FIG. 1) and then presses the [Delete] button 182, the item is deleted. Needless to say, an item once deleted can be input again by the above-described additional operation.

  Further, the operator can delete all items displayed in the display columns 174, 176, and 178 by pressing the [Delete All] button 184.

  Next, the worker evaluates each candidate condition based on the condition evaluation information (step S2).

  Here, the condition evaluation information is information for evaluating the suitability (color reproducibility) of the print color reproduction conditions with respect to the data of the electronic document to be printed. Contains image data. The details of the condition evaluation information generation method and evaluation method will be described later.

  Next, the operator selects one print color reproduction condition (hereinafter referred to as “selection condition”) from the candidate conditions based on the evaluation result performed in step S2 (step S3). A print profile corresponding to the selection condition is also selected.

  If an appropriate profile is not registered in the printing machine 18 (stored in the storage unit 80 or the like), the print profile is generated by the profile generation unit 62 shown in FIG. The print profile generation method is the same as the generation method by the profile generation unit 136 constituting a part of the color reproduction simulation unit 70, and will be described in detail later.

  Next, the operator prints an electronic document using the printing machine 18 to obtain a printed matter 38 (step S4). Here, the flow of image processing by the image processing device 16 when printing an electronic document will be described in detail with reference to FIG.

When an electronic manuscript (PDL format) supplied from the editing device 14 is input to the image processing device 16 via the LAN 12 and the I / F 52, the electronic manuscript is RIP 54, and the 8-bit CMYK bitmap format (device) is used. Dependent image data), converted to L ^* a ^* b ^* (device-independent image data) by the target profile processing unit 82, and converted to CMYK values (device-dependent image data) by the print profile processing unit 84. Then, it is converted into a print signal (that is, ink ejection control data) by the printer driver 58 and supplied to the printer 18 via the I / F 60. Thereafter, a desired printed matter 38 is printed by the printing machine 18.

  At this time, the profile set in the text box 154a of the setting screen 150 (see FIG. 7) is used as the target profile. Further, a profile corresponding to the selection condition selected in step S3 is used as a print profile.

  The target profile and the print profile are supplied from the storage unit 80 to the black point correction processing unit 64, and after black point correction is performed by the black point correction processing unit 64 as necessary, the target profile processing unit 82 and the print profile processing unit 84. To be supplied.

  For example, when the printed matter 38 is covered with the laminate film 40, the black point correction processing unit 64 can correct the black point of the color conversion LUT 124 included in the printing profile.

  Here, the black point correction is referred to as a color value of a black point on a boundary of a gamut related to the first profile (hereinafter referred to as “first gamut”) and a gamut related to the second profile (hereinafter referred to as “second gamut”). ) Color conversion processing for mapping so as to match the color value of the black point on the boundary.

  As an algorithm for performing black point correction, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2004-153554 can be used. An outline of this method will be described with reference to FIGS. 10A to 10C.

FIG. 10A is a graph showing the positional relationship between the first gamut 210 and the second gamut 212 before black point correction is performed. The horizontal axis of this graph is defined as a ^* , and the vertical axis is defined as L ^* , which represents a cross-sectional view of the three-dimensional color space L ^* a ^* b ^* . The same applies to the coordinate axis definitions of the graphs shown in FIGS. 10B and 10C.

  For example, it is assumed that the first gamut 210 is a gamut when the medium 36 is not covered with the laminate film 40 and is observed under the light source LS. The second gamut 212 is assumed to be a gamut when the medium 36 is covered with the laminate film 40 and observed under the light source LS. That is, consider a case where a difference between the first gamut 210 and the second gamut 212 occurs depending on whether the laminate film 40 is covered.

  The white point in the first gamut 210 is wt1, the black point is bk1, the white point in the second gamut 212 is wt2, and the black point is bk2.

  First, each gamut is translated downward so that the black point bk1 of the first gamut matches the black point bk2 of the second gamut. In this way, the first gamut 210s and the second gamut 212s after translation are obtained. As shown in FIG. 10B, the color value of the black point bk1 'after the conversion of the black point bk1 and the color value of the black point bk2' after the conversion of the black point bk2 are both (0, 0, 0).

  Next, gamut conversion is performed so that the white point wt1 'of the first gamut 210s matches the white point wt2' of the second gamut 212s while maintaining the coincidence between bk1 'and bk2'. Here, since the area of the first gamut 210s is larger than the area of the second gamut 212s, conversion for enlarging the second gamut 212s upward is performed.

  In this embodiment, a Von-Kries transformation, which is a kind of chromatic adaptation model, is applied to use a method of matching white spots while fixing black spots. The conversion algorithm is not limited to this, and for example, gamut similarity conversion (change of ratio), Bradford conversion, CIECAM97s conversion, CIECAM02s conversion, or the like may be used.

  In this way, the second gamut 212k after Von-Kries conversion is obtained. As shown in FIG. 10C, the color value of the white point wt1 'matches the color value of the white point wt2 "after conversion of the white point wt2'.

  As described above, by performing mapping (in this embodiment, parallel movement of gamut) so that the color value of the black point related to the first profile matches the color value of the black point related to the second profile, the printed matter 38 is obtained. In particular, the color reproducibility in the shadow region can be substantially matched between the printed matter 42 and the printed matter 42 with the protective film.

  Next, returning to FIG. 9, a laminate process is performed on the printed matter 38 obtained by the printing machine 18 (step S5).

  Specifically, with the laminate film 40 being stuck on the image forming surface of the printed matter 38 (and further on the back surface if necessary), heating and pressing are performed using a heating roller (not shown) provided in the laminating apparatus 20. By performing the treatment, a printed matter 42 with a protective film is obtained. As a result, it is possible to improve the scratching and robustness of the image. Needless to say, step S5 can be omitted when the printed matter 38 is not covered with the laminate film 40.

  Next, the color of the color image of the printed matter 42 with the protective film is evaluated (step S6), and it is determined whether or not the color of the image is appropriate (step S7). As an evaluation method for determining whether or not a desired hue has been obtained, paying attention to the overall appearance or partial appearance of the image, a method for judging the quality by visual observation by an operator or the like, or using a colorimeter 22 For example, a method of measuring the color of a predetermined portion of the printed matter 42 with the protective film and determining whether or not the value falls within a desired range is used.

  As a result of this image evaluation, when it is determined that the color of the image of the printed matter 42 with the protective film is not appropriate, another print color reproduction condition is selected from the other candidate conditions, and printing and evaluation are repeated (step S3). To S7). In this way, a printed matter 42 with a protective film having a desired color is obtained.

  Heretofore, the flowchart for obtaining the printed matter 42 with the protective film appropriately color-adjusted using the printing system 10 according to the present embodiment has been described. Next, the method for evaluating each candidate condition (step S2) will be described in more detail.

  FIG. 11 is a flowchart regarding a method for evaluating each candidate condition based on the condition evaluation information.

  First, all print color reproduction conditions that can be selected from each designated group are set as candidate conditions (step S21). Here, the designated groups are the media 36 group, the laminate film 40 group, and the light source LS group designated on the setting screen 150 (see FIG. 7) and displayed in the display columns 174, 176, and 178.

  As shown in FIG. 6, information on each designated group that can be an evaluation target is supplied from the storage unit 80 to the candidate condition setting unit 134, and the candidate condition is set by the candidate condition setting unit 134. Candidate conditions are all print color reproduction conditions that can be selected from each designated group, and generally all combinations of the media 36 group, the laminate film 40 group, and the light source LS group can be adopted. Note that the predetermined print color reproduction conditions may be limited in advance, and only the print color reproduction conditions may be excluded. Here, N candidate conditions are set.

  Next, a print profile corresponding to each candidate condition is generated (step S22).

  As illustrated in FIG. 6, each print profile is generated by the profile generation unit 136 based on the spectral data supplied from the storage unit 80 and the candidate conditions supplied from the candidate condition setting unit 134. Hereinafter, a description will be given with reference to FIGS. 4 and 5.

  As shown in FIG. 4, the setting data 100 supplied from the storage unit 80, the spectral data group 102 of the medium, the spectral data group 104 of the laminate film, and the spectral data group 106 of the observation light source are set as candidate conditions. The data selection unit 86 selects the first, second, and third spectral data 112, 114, and 116 associated with the data 100.

  Further, as shown in FIG. 5, a predetermined mathematical model is generated based on the first and second spectral data 112 and 114 by the reflectance / transmittance prediction unit 88 a constituting a part of the colorimetric value calculation unit 88. Is applied to predict the fourth spectral data 118 (that is, the spectral reflectance or the spectral transmittance of the printed matter 42 with the protective film).

When the medium 36 is a reflection medium, a Kubelka-Munk (hereinafter referred to as “Kubelka-Munk”) model can be applied. Specifically, the spectral reflectance R of the printed matter 42 with the protective film is predicted based on the following equation (1). Each variable is a function for each light wavelength, but is omitted for convenience of explanation.
_{R = [(R g -R∞)} / R∞-R∞ (R g -1 / R∞) exp {Sx (1 / R∞-R∞)}] / [(R g -R∞) - ( R _g −1 / R∞) exp {Sx (1 / R∞−R∞)}] (1)

Here, [R _g ] is the spectral reflectance of the printed matter 38 alone (first spectral data 112), [R∞] is the spectral intrinsic reflectance of the laminate film 40, and [S] is the unit thickness of the laminate film 40. [X] represents the thickness of the laminate film 40 (“New Contribution to the Optics of Intense Light-Scattering Materials. Part I, JOURNAL OF THEU LIFE 48 , MAY, 1948).

  On the other hand, when the medium 36 is a transmissive medium, the spectral transmittance of the printed matter 42 with the protective film can be accurately estimated by multiplying the spectral transmittance of the medium 36 and the laminate film 40.

Returning to FIG. 5, the Lab calculation unit 88 b calculates the colorimetric value data 120 under the profile generation condition based on the third spectral data 116 and the fourth spectral data 118. Here, the colorimetric value data 120 under the profile generation condition is L ^* a ^* b ^* when the printed matter 42 with the protective film is observed under the light source LS, which is estimated based on the actual measurement data.

Specifically, the tristimulus values XYZ of each color patch 44 are multiplied by the spectral radiation distribution of the light source LS, the spectral reflectance (or spectral transmittance) of the printed matter 42 with a protective film, and the color matching function, and are visible. It corresponds to the value integrated within the range of the optical wavelength. Based on the tristimulus values XYZ and a predetermined arithmetic expression, L ^* a ^* b ^* of each color patch 44 as the colorimetric value data 120 is calculated. In the present embodiment, since 100 color patches 44 are measured, 100 sets of L ^* a ^* b ^* are obtained.

Then, the LUT generation unit 90 shown in FIG. 4 uses the three-dimensional data as a print profile based on the correspondence between 100 sets of colorimetric value data (L ^* a ^* b ^* ) 120 and 100 sets of CMYK value data 122. A color conversion LUT 124 that converts (L ^* a ^* b ^* ) into four-dimensional data (CMYK) can be generated.

  That is, each spectral reflectance (or spectral transmittance) corresponding to each lattice point of the color conversion table is determined based on the spectral reflectance (or spectral transmittance) of the printed matter 42 with the protective film, and each spectral reflectance ( Alternatively, a profile of the printed matter 42 with the protective film is generated based on the spectral transmittance.

  With this configuration, once the spectral data of the media 36, the laminate film 40, and the light source LS are acquired, the print profile can be estimated without forming the printed matter 42 with the protective film. Thereby, the number of series of operations for profile generation can be reduced. This series of operations includes printing of the color chart 38c by the printing machine 18 (including a waiting time), laminating by the laminating apparatus 20, and colorimetry by the colorimeter 22.

  In this way, a print profile corresponding to each candidate condition is generated (step S22).

  Next, returning to FIG. 11, the target color in each pixel of the image data is calculated using the target profile (step S23).

  As shown in FIG. 6, the same data as the electronic document to be actually printed is supplied to the image enlargement / reduction processing unit 130, and is rasterized as necessary by the image enlargement / reduction processing unit 130. Are thinned out (that is, image reduction processing is performed), and new image data (hereinafter referred to as “thinned image data”) is generated. This is preferable because the time required for the subsequent image processing can be shortened.

Thereafter, the thinned image data is supplied from the image enlargement / reduction processing unit 130 to the target color calculation unit 132, and is converted into target color data (for example, L ^* a ^* b ^* ) that is device-independent data by the target color calculation unit 132. Is done. For this conversion, the color conversion LUT 124 included in the target profile supplied from the storage unit 80 is used. Needless to say, this process can be omitted when the thinned-out image data is device-independent data.

  Next, i = 1 is set, and i representing the candidate condition correspondence number is initialized (step S24).

  Next, the reproduction color at each pixel of the thinned image data is predicted using the i-th print profile (step S25). The target color data supplied from the target color calculation unit 132 is converted into a reproduction color corresponding to each pixel using the i-th print profile (color conversion LUT 124) generated by the profile generation unit 136 by the reproduction color prediction unit 138. Converted.

  Next, it is determined whether or not color reproduction is possible for each pixel of the image data (step S26). This discrimination processing is performed for each pixel using the target color data supplied from the target color calculation unit 132 and the reproduction color data supplied from the reproduction color prediction unit 138 (or the print profile supplied from the profile generation unit 136). Is made.

  Specifically, the determination can be made based on whether or not the target color corresponding to each pixel belongs to a gamut (hereinafter referred to as “reproduction gamut”) formed by the print profile. Further, the determination may be made based on whether or not the color difference between the reproduction color corresponding to each pixel and the target color falls within a predetermined range. Since colors can be accurately reproduced if they are within the reproduction gamut range, the gamut genus (for example, within the reproduction gamut range if ΔE <3) may be estimated based on the color difference.

  Next, condition evaluation information for the i-th print profile, that is, the i-th candidate condition is generated (step S27).

  The result of reproducibility on each pixel supplied from the reproducibility determination unit 140 is supplied to the condition evaluation information generation unit 142, and the condition evaluation information generation unit 142 generates condition evaluation information. As described above, the condition evaluation information may be a single or a plurality of evaluation values, or may be image data for evaluation.

  As the first condition evaluation information, a ratio (percentage) of the number of pixels corresponding to the color determined to be reproducible with respect to the number of pixels of the image data, that is, a reproducibility rate may be used.

  Further, as a first modification of the reproducibility rate, an evaluation value may be obtained by weighting according to the color area of the color space coordinates and adding the weight for each pixel. This increases the evaluation specific gravity in the color region in which the operator places importance on color reproducibility, so that it is easy to select a print color reproduction condition that meets the operator's request. For example, when the operator presses an [important color designation] button 156 shown in FIG. 7, the operator is shifted to another setting screen (not shown), and a predetermined value that the operator attaches importance to in the displayed color space coordinate map is displayed. The color area may be freely selected.

  Furthermore, as a second modification of the reproducibility rate, weighting according to the image area of the image data may be performed and added for each pixel to obtain an evaluation value. This increases the evaluation specific gravity in the image area where the operator places importance on color reproducibility, so that it is easy to select the print color reproduction condition that meets the operator's request. For example, when the worker presses a [specify important color] button 156 shown in FIG. 7, a transition is made to another setting screen (not shown), and a predetermined image area that the worker places importance on among the displayed color images. May be selected freely.

  Furthermore, as a third modification of the reproducibility rate, an evaluation value that places importance on high chroma color may be obtained. For example, the evaluation specific gravity for a color whose saturation exceeds a predetermined value can be increased. A state where a check mark is added to the [High Saturation Emphasis] check box 158 shown in FIG. 7 corresponds to ON, and a state where the check mark is deleted from the check box 158 corresponds to OFF.

  Furthermore, as a fourth modification example of the reproducibility rate, an evaluation value that places importance on the shadow color may be obtained. For example, the evaluation specific gravity can be increased for colors whose brightness does not exceed a predetermined value. A state where a check mark is added to the [Shadow Emphasis] check box 160 shown in FIG. 7 corresponds to ON, and a state where the check mark is deleted from the check box 160 corresponds to OFF.

  Image data corresponding to the address of each pixel may be used as the second condition evaluation information. Thereby, the state of color reproducibility in each pixel can be distinguished. For example, when the target color is a color within the reproduction gamut range and the color difference from the reproduction color is within the predetermined range, “3”, the target color is a color within the reproduction gamut range, but the reproduction color "2" when the color difference from the color exceeds the predetermined range, "1" when the target color is not within the reproduction gamut range but the color difference from the reproduction color is within the predetermined range, the target color is reproduced If the color difference is not within the gamut range and the color difference from the reproduced color exceeds a predetermined range, quaternary image data to which “0” is given may be generated.

  The condition evaluation information generated in this way is supplied to the evaluation image data generation unit 144 or temporarily stored in the storage unit 80. Thereafter, the condition evaluation information is converted into evaluation image data by the evaluation image data generation unit 144.

  As will be described later, a value of a pixel determined that the target color does not belong to the reproduction gamut may be replaced with a value that can be determined by visualizing that the target color does not belong. That is, when observing the evaluation image output to the display device 26 or the like, the target color is converted into a different color value that can be clearly identified in comparison with the color value of the pixel determined to belong to the reproduction gamut. May be.

  For example, it may be an achromatic color such as black or gray, or a highly saturated color such as red or blue. Or you may analyze the histogram of image data and use a color with low use frequency. Then, the operator can grasp visually and sensuously whether or not colors can be reproduced.

  Next, it is determined whether or not all N candidate conditions have been completed (step S28). If it is determined that they have not been completed, i is counted up (step S29), and the next i + 1th candidate condition is determined. Similar operations are repeated (steps S25 to S27).

  Finally, the evaluation result is displayed (step S30). The generated evaluation image data is supplied from the evaluation image data generation unit 144 to the display profile processing unit 146, converted into RGB values by the display profile processing unit 146, and sent to the display device 26 side via the I / F 72. Supplied and displayed as a visible image by the display device 26.

  12A to 12C are diagrams illustrating display examples of the image data for evaluation generated by the color reproduction simulation unit 70 in FIG. In practice, a color image is displayed in the window 220, but for convenience of explanation, only the outline is drawn with the colors omitted.

  FIG. 12A shows evaluation image data when the medium 36 is “PVC B”, the laminate film 40 is “MAT B”, and the light source LS is “F8”.

  When the operator presses an [image display] button 194b shown in FIG. 8, another window 220 is newly displayed. The first evaluation image data 222 is displayed at the center of the window 220, and a check box 224 and a button 226 displayed as [Close] are provided below the first evaluation image data 222, respectively. When the operator presses the button 226, the window 220 is closed and hidden.

  As shown in the display column 204 of FIG. 8, the reproducibility rate is 78%, and it can be confirmed that the color image has low color reproducibility. When it is difficult to determine the difference in color reproducibility, the operator adds a check mark to the check box 224 “gamut display” using the mouse 32 (see FIG. 1) (check box 230). As shown, the pixel value determined that the target color does not belong to the reproduction gamut range is replaced with a value corresponding to gray (for example, 8-bit gradation display, R = G = B = 30). It is displayed as second evaluation image data 228 (area indicated by hatching). Thereby, the operator can grasp at a glance whether the color reproducibility is good or bad.

  Further, the region indicated by double hatching in FIG. 12B is displayed with a value corresponding to a value corresponding to blue (for example, 8-bit gradation display, R = G = 0, B = 255) as an example. This region represents a set of pixels having a color within the range of the reproduction gamut when the laminate film 40 is not covered, but is a color outside the range of the reproduction gamut when the laminate film 40 is covered. Thereby, the influence degree by the presence or absence of the laminate film 40 can be grasped at a glance.

  FIG. 12C shows the evaluation image data when the medium 36 is “PVC A”, the laminate film 40 is “MAT C”, and the light source LS is “F8”. When the operator presses an [image display] button 194g shown in FIG. 8, another window 220 is newly displayed.

  As shown in the display column 204 of FIG. 8, the reproducibility rate is 92%, and it can be confirmed that the color image has high color reproducibility. Even if a check mark is added to the check box 230, the pixel replaced with gray or blue is displayed in the third evaluation image data 232 with little noticeability.

  In this way, each candidate condition is evaluated (step S2), and one print color reproduction condition is selected (step S3). Candidate conditions with the best evaluation results may be automatically selected, or may be helped by the operator.

  Now, a method for acquiring the spectral data group 102 of the media, the spectral data group 104 of the laminate film, and the spectral data group 106 of the observation light source used for generating the print profile will be described in detail.

  First, a method for acquiring spectral data (first spectral data 112) of the medium 36 will be described. Specifically, a method for directly acquiring the spectral reflectance or spectral transmittance of the medium 36 using the colorimeter 22 connected to the main body 24 will be described mainly with reference to FIG.

  The operator requests printing of the color chart 38c from a setting screen (not shown) displayed on the display device 26. Then, image data (CMYK value) for printing the color chart 38c is generated by the image data generation unit 66 of the main body 24, supplied to the printer driver 58, and the printer 18 side by the same operation as the printing of the electronic document. To be supplied. In this way, the color chart 38c (see FIG. 2) is printed.

  Note that the CMYK value data 122 (see FIG. 4) corresponding to the pixel values of each color patch 44 is stored in the storage unit 80 in advance, and is read from the storage unit 80 when image data is generated.

  The operator does not perform the laminating process by the laminating apparatus 20 (see FIG. 1), and uses the colorimeter 22 connected to the image processing apparatus 16 to each color patch 44 of the color chart 38c (see FIG. 2). Measure spectroscopic data. Note that the spectral reflectance is measured when the medium 36 is a reflective medium, and the spectral transmittance is measured when the medium 36 is a transmissive medium.

  For example, as shown in FIG. 2, each color is represented by (01) to (10) in the (A) column and (01) to (10) in the (B) column indicated by the numeric string 46 and the alphabetic character string 48. It is preferable to determine in advance the order of color measurement of the patch 44. Based on the notification of color measurement completion by the operator, spectral data corresponding to each color patch 44 is stored in the storage unit 80 in association with the type of the medium 36 via the I / F 76 (see FIG. 3).

  Secondly, a method for obtaining the spectral data (second spectral data 114) of the laminate film 40 will be described.

  The spectral transmittance of the laminate film 40 can be measured using the colorimeter 22 connected to the main body 24. On the other hand, it is difficult to directly measure R∞ (inherent reflectance) and Sx (scattering coefficient) using the colorimeter 22.

  Therefore, a method for experimentally estimating R∞ and Sx, which are unknown variables, by measuring the color of a measurement sample using the colorimeter 22 and will be described mainly with reference to FIG.

FIG. 13 is a schematic cross-sectional view of a measurement sample 240 produced for estimating the optical property value of the laminate film 40. The measurement sample 240 includes a base material 242 having a spectral reflectance Rg ₁ made of a white opaque body, a black material 244, and a laminate film 40 as a measurement target.

The operator uses the colorimeter 22 to measure the spectral reflectance of each part of the measurement sample 240. As a result, the spectral reflectance when the laminate film 40 is coated on the base 242 is R ₁ , the spectral reflectance when the black material 244 is provided on the base 242 is Rg ₂ , and the base 242 is covered. It is assumed that a measured value having a spectral reflectance R ₂ (R ₁ > R ₂ ) when the laminate film 40 is coated via the black material 244 is obtained.

  This measurement value is temporarily stored in the storage unit 80 via the I / F 76 provided in the image processing apparatus 16 (main body 24) shown in FIG. Thereafter, the optical property value estimation unit 68 is supplied to perform arithmetic processing according to the following mathematical formula.

The intrinsic reflectance R∞ of the laminate film 40 is calculated by mathematical analysis.
R∞ = {C−√ (C ² −4)} / 2 (2)
C = {(R ₁ + Rg ₂ ) (R ₂ · Rg ₁ -1)-(R ₂ + Rg ₁ ) (R ₁ · Rg ₂ -1)} / (R ₂ · Rg ₁ -R ₁ · Rg ₂ ) ... (3)
(Refer to “Special Articles on Paper: Takaga Paper, But Paper, Again Paper”, “Paper Characteristics, Evaluation Methods, and Trends in Standards” (2004, Journal of the Imaging Society of Japan 150)). When R ₁ <R ₂ , the subscripts 1 and 2 in the formula (3) are reversed.

  Here, the intrinsic reflectance R∞ is a reflectance when it is assumed that the sample has an infinite thickness. Therefore, when it is possible to form a large number of laminated films 40 of the same type, the intrinsic reflectance R∞ may be directly measured.

Next, using the measured value R _n (n = 1 or 2), the measured value Rg _n (n = 1 or 2), and R∞ calculated by the equation (2), the scattering coefficient S of the laminate film 40 and The thickness x is
S · x = ln [{( R∞-Rg n) (1 / R∞-R n)} / {(R∞-R n) (1 / R∞-Rg n)}] / (1 / R∞ -R∞) (4)
(See “Color Reproduction Fundamentals and Applied Technologies”, page 88, formula (21) (triceps)).

  Here, S is a scattering coefficient per unit thickness, and x is the thickness of the laminate film 40. Regarding the definition of the scattering coefficient, for convenience of explanation, Sx (= S · x) is defined as the scattering coefficient at the film thickness x (that is, one variable), but either S or Sx may be used. The same applies to the absorption coefficient K.

  As described above, the optical property values (the intrinsic reflectance R∞ and the scattering coefficient Sx) of the laminate film 40 can be estimated using the measurement sample 240 in which the base material 242, the black material 244, and the laminate film 40 are combined. .

  Thirdly, a method for obtaining the spectral radiation distribution (third spectral data 116) of the laminate film 40 will be described.

  When the medium 36 is a reflection medium, the operator can directly obtain the spectral data of the light source LS by performing measurement with a non-contact colorimeter (not shown) directed toward the white reference plate. Further, when the medium 36 is a transmissive medium, the operator can directly acquire the spectral data of the light source LS by performing the measurement with the non-contact colorimeter directed at the light source.

  In addition to the method described above, the first, second and third spectral data 112, 114 and 116 are managed in a database DB (see FIG. 1), and the spectral data is managed from the database DB as necessary. The structure which can acquire desired spectral data may be sufficient. Further, desired spectral data may be acquired from a portable memory 34 (see FIG. 1) connected to the main body 24.

  As described above, all the print color reproduction conditions that can be selected from each designated group (the media 36 group, the laminate film 40 group, and the light source LS group) to be evaluated are set as candidate conditions. First spectral data 112 of the printed matter 38 obtained by printing on each medium 36 corresponding to the candidate condition, second spectral data 114 of each laminate film 40, and third spectral data 116 of each light source LS Each print profile is generated based on the print profile, and the reproduction color corresponding to the pixel of the image data is predicted based on each print profile corresponding to each of the generated candidate conditions. Condition evaluation information for determining whether or not the color reproduction on the pixel is reproducible based on the target color and evaluating each candidate condition based on the determined reproducibility Therefore, the operator can narrow down the conditions efficiently within the range of the evaluation target specified in advance, and the printed matter 38 is formed for each different print color reproduction condition, and the color of the printed matter 38 is formed. There is no need to evaluate reproducibility, and it is possible to easily and appropriately evaluate the color reproducibility of the printed matter 38 from a large number of condition combinations.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change freely in the range which does not deviate from the main point of this invention.

  For example, in this embodiment, the number of color patches 44 included in the color chart 38c is 100, the number of spectral data is 41 points, and the interval between light wavelengths is 10 nm. However, the color reproduction accuracy, the image processing time, and the like are comprehensive. In consideration of the above, it may be configured such that these can be freely changed.

  Further, in the present embodiment, the Kubelka-Munk model is used as a prediction formula for the colorimetric value of the printed matter 42 with the protective film, but it goes without saying that a modified expression thereof or another mathematical model can also be applied.

  Further, since the profile generation unit 62 and the profile generation unit 136, the target profile processing unit 82 and the target color calculation unit 132, the print profile processing unit 84, and the display profile processing unit 146 are the same as the LUT processing function, they are common modules. May be used.

  Further, in the present embodiment, the printing machine 18 employs a configuration that uses an ink jet method, but the present invention is not limited thereto, and the effects of the present invention can be obtained even with an electrophotography, a heat sensitive method, or the like.

DESCRIPTION OF SYMBOLS 10 ... Printing system 14 ... Editing apparatus 16 ... Image processing apparatus 18 ... Printing machine 20 ... Laminating apparatus 22 ... Colorimeter 24 ... Main body 26 ... Display apparatus 36 ... Media 38 ... Printed matter 38c ... Color chart 40 ... Laminate film 42 ... Printed matter with protective film 44 ... Color patch 52, 60, 72, 74, 76, 78 ... I / F
54 ... RIP 56 ... color conversion processing unit 58 ... printer driver 62, 136 ... profile generation unit 64 ... black point correction processing unit 66 ... image data generation unit 68 ... optical property value estimation unit 70 ... color reproduction simulation unit 80 ... storage unit 82 ... Target profile processing unit 84 ... Print profile processing unit 86 ... Data selection unit 88 ... Colorimetric value calculation unit 88a ... Reflectance / transmittance prediction unit 88b ... Lab calculation unit 90 ... LUT generation unit 100 ... Setting data 102 ... Media Spectral data group 104 ... Spectral data group of laminate film 106 ... Spectral data group 112 of observation light source ... First spectral data 114 ... Second spectral data 116 ... Third spectral data 118 ... Fourth spectral data 120 ... Colorimetric value data 122 ... CMYK value data 124 ... Color conversion LUT 130 ... Image enlargement / reduction processing unit 132 ... Eye Color calculation unit 134 ... Candidate condition setting unit 138 ... Reproduction color prediction unit 140 ... Reproducibility determination unit 142 ... Condition evaluation information generation unit 144 ... Evaluation image data generation unit 146 ... Display profile processing units 162, 164, 166 ... Pull-down menu 152a, 154a ... text boxes 152b, 154b, 156, 168, 170, 172, 180, 182, 184, 194, 194b, 194g ... buttons 158, 160 ... check boxes 174, 176, 178, 192, 198, 200, 202 , 204, 206 ... display field 186 ... frame 196 ... item field 210, 210s ... first gamut 212, 212s, 212k ... second gamut 240 ... measurement sample 242 ... base material 244 ... black material

Claims (19)

A print color reproduction condition evaluation method for predicting and evaluating color reproducibility when applying print color reproduction conditions including information on a medium, a protective film, and an observation light source to image data representing a color image. ,
A designation step for designating a media group, a protective film group, and an observation light source group to be evaluated;
A setting step of setting all print color reproduction conditions that can be selected from the specified media group, the protective film group, and the observation light source group as candidate conditions;
Each print profile is generated based on the optical property value of the printed matter obtained by printing on each medium corresponding to each of the set candidate conditions, the optical property value of each protective film, and the spectral distribution of each observation light source A profile generation step,
A prediction step of predicting a reproduction color corresponding to a pixel of the image data based on each of the print profiles corresponding to each of the generated candidate conditions;
A determination step of determining whether or not the color can be reproduced on the pixel based on the predicted reproduction color and a target color at the time of printing;
A condition evaluation information generating step for generating condition evaluation information for evaluating each of the candidate conditions based on the determined reproducibility, and a print color reproduction condition evaluation method. In the evaluation method of printing color reproduction conditions according to claim 1,
The method of evaluating a printing color reproduction condition, wherein the determining step determines whether or not the color can be reproduced on the pixel depending on whether or not the target color belongs to a reproduction gamut at the time of printing. In the evaluation method of the printing color reproduction conditions according to claim 1 or 2,
The condition evaluation information is a ratio of the number of pixels corresponding to a color determined to be reproducible with respect to the number of pixels of the image data. In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-3,
The condition evaluation information is evaluation image data in which a pixel value of each pixel is determined so that the reproducibility of the color corresponding to each pixel of the color image can be visualized and determined. Evaluation method of characteristic print color reproduction conditions. In the evaluation method of the printing color reproduction conditions according to claim 4,
The evaluation image data can be further determined by visualizing the reproducibility of the color corresponding to each pixel of the color image under the print color reproduction condition when the protective film is not covered under the print color reproduction condition. It is image data in which the pixel value of each said pixel was determined as follows. The evaluation method of the printing color reproduction conditions characterized by the above-mentioned. In the evaluation method of the printing color reproduction conditions according to claim 4 or 5,
The printing color reproduction condition evaluation method further comprising the step of displaying the evaluation image data. In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-6,
Further comprising a step of setting a predetermined image area of the color image;
The reproducibility is determined on each pixel in the set image area. A method for evaluating a print color reproduction condition, characterized in that: In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-6,
Further comprising a step of setting a predetermined color area in the color space coordinates;
The reproducibility is discriminated on each pixel corresponding to the color in the set color region. The method for evaluating a print color reproduction condition, In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-8,
The condition evaluation information is an evaluation value obtained by weighting a numerical value determined based on the reproducibility result according to an image area of the color image and adding the weight for each pixel of the color image. A method for evaluating printing color reproduction conditions, characterized by being. In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-8,
The condition evaluation information is an evaluation value obtained by weighting a numerical value determined based on the reproducibility result according to a color area of a color space coordinate and adding the value for each pixel of the color image. A method for evaluating printing color reproduction conditions, characterized by being. In the evaluation method of printing color reproduction conditions according to claim 10,
Black point correction so that the color value of the black point related to the profile when the protective film is coated under the print color reproduction condition matches the color value of the black point related to the profile when the protective film is not covered under the print color reproduction condition The printing color reproduction condition evaluation method further comprising the step of: In the evaluation method of printing color reproduction conditions according to claim 11,
The method for evaluating a printing color reproduction condition, further comprising a step of selecting whether or not to perform the black spot correction. In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-12,
Further comprising generating new image data by thinning out pixels of the image data;
Evaluation of print color reproduction conditions characterized by predicting and evaluating color reproducibility when the print color reproduction conditions are applied to the image data by using the new image data instead of the image data Method. In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-13,
When the medium is a reflective medium, the optical physical property value of the printed matter related to the medium is a spectral reflectance, and the optical physical property value of the protective film is an intrinsic reflectance, a scattering coefficient, and an optical wavelength value of the protective film. A method for evaluating printing color reproduction conditions, characterized in that they are two independent optical property values of the absorption coefficient. In the evaluation method of printing color reproduction conditions given in any 1 paragraph of Claims 1-13,
When the medium is a transmission medium, the optical property value of the printed material and the protective film relating to the medium is a spectral transmittance. A step of selecting one print color reproduction condition based on the obtained evaluation result using the print color reproduction condition evaluation method according to any one of claims 1 to 15. How to select color reproduction conditions. A color conversion method comprising: a step of color-converting the image data using a print profile corresponding to the selected print color reproduction condition using the method for selecting a print color reproduction condition according to claim 16. . A condition selection unit for selecting the one print color reproduction condition using the method for selecting a print color reproduction condition according to claim 16;
A color conversion apparatus comprising: a color conversion processing unit that performs color conversion of the image data using a print profile corresponding to the one print color reproduction condition selected by the condition selection unit. In order to predict and evaluate color reproducibility when applying print color reproduction conditions including information on media, protective film and observation light source to image data representing a color image,
Means for designating the media group, protective film group and observation light source group to be evaluated;
Means for setting, as candidate conditions, all print color reproduction conditions that can be selected from the designated media group, the protective film group, and the observation light source group;
Each print profile is generated based on the optical property value of the printed matter obtained by printing on each medium corresponding to each of the set candidate conditions, the optical property value of each protective film, and the spectral distribution of each observation light source Means to
Means for predicting a reproduction color corresponding to a pixel of the image data based on each of the print profiles corresponding to each of the generated candidate conditions;
Means for determining whether or not a color can be reproduced on the pixel based on the predicted reproduction color and a target color at the time of printing;
A program that functions as means for generating condition evaluation information for evaluating each candidate condition based on the determined reproducibility.

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