JP2009089008A - Image processing system and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system which performs color conversion based on a profile to an input image, to output from a printer, and further optimizes a color pattern of a color patch in a color chart for producing the profile in consideration of a color distribution of the image as a printing object. <P>SOLUTION: A reference image for producing the profile is inputted (S201), and analyzed to obtain an image characteristic (S202). The color pattern of the color patch is set in response to the image characteristic (S203), and a test chart by the set color patch is outputted to the printer (S204). Then, a color of the color patch in the test chart outputted from the printer is measured (S205), and the profile is produced based on the color measurement value (S207). When this takes place, a lattice point position of a LUT of the profile is set in response to the analyzed image characteristic (S206). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image processing system and a control method thereof, and more particularly, to an image processing system for creating a color profile and a control method thereof.

  High-end users such as graphic artists and photographers are increasingly using the printer as a professional work tool as the accuracy of the printer increases, such as higher resolution and large format. In general, such a high-end user strongly desires that a color designated by the user is accurately reproduced when printing is performed by a printer.

  Conventionally, as color processing in a printer, color conversion using a printer profile (hereinafter simply referred to as a profile) is performed in order to perform printing with accurate colors. A profile defines a correspondence between coordinates of a color space (RGB space, etc.) depending on a device (in this case, a printer) and coordinates of a color space (CIE-LAB space, etc.) independent of the device. For example, it is created in the LUT (Look Up Table) format.

  By using such a profile, an original image is subjected to color conversion between a device-dependent color space and a device-independent color space, and the color-converted image is printed out by a printer. The color can be reproduced.

  The accuracy (color reproduction accuracy) for realizing an accurate color by the printer varies depending on the profile configuration. In general, a profile is created based on colorimetric values of a plurality of color patches formed in a color chart output from a printer. Since a plurality of profiles may be created depending on the application of the printer, it is desirable to use a common color chart in which color patches are efficiently arranged. In general, as a profile configuration, a color chart called IT8, or a color patch corresponding to each grid point on a predetermined grid assumed in the color space corresponds to an array of grid points on the color space. A lattice color chart or the like arranged in the above is used. These color charts are suitable for creating general-purpose profiles, and color patches are arranged so that the color reproduction accuracy is generally high in an arbitrary input image.

However, for a high-end user as described above, a general color chart corresponding to an arbitrary input image may lack color reproduction accuracy. Therefore, as a technique for further improving the color reproduction accuracy by the profile, a technique for optimizing the color patch color arrangement in the color chart according to the use application of the printer (for example, printing a photograph, etc.) has been proposed (for example, , See Patent Document 1).
JP 2006-148700 A

  However, as in the technique described in Patent Document 1, it is not possible to create a profile for printing and outputting a document with higher accuracy only by classification based on the intended use of the printer.

  According to the technique described in Patent Literature 1, for example, for printing an image, a color chart according to a profile can be used by using a color chart in which color patches of a low saturation color are arranged more than a high saturation color. The reproduction accuracy has been improved to be more specialized for photography.

  Here, for example, consider a case where an ID photo of a person's face taken in a dedicated studio is printed. In this case, since the color to be printed is mainly the background gray (gray) and the skin color of the person, it is almost unnecessary to arrange a color patch of high saturation color as a color chart for profile creation. Therefore, in this case, it is possible to improve the color reproduction accuracy of the created profile by eliminating all high-saturation color patches from the color chart and changing the color scheme of the patches so that only the skin color and gray color patches are obtained. it can.

  In this way, in order to create a profile that achieves high-precision color reproduction for a printer, the color patch color scheme in the color chart for profile creation is taken into account in consideration of the color distribution of the input image (original) to be printed. It is effective to optimize

  SUMMARY An advantage of some aspects of the invention is that it provides an image processing system having the following functions and a control method thereof. That is, by optimizing the color patch color arrangement in the color chart in accordance with the profile creation reference image, a profile that realizes optimum color reproduction for the reference image is created.

  As a means for achieving the above object, an image processing system of the present invention comprises the following arrangement.

  That is, an image processing system that performs color conversion based on a profile on an input image in an image processing apparatus and outputs the image after the color conversion from the image output apparatus, wherein the image processing apparatus performs reference for profile creation An image input means for inputting an image, an analysis means for analyzing the reference image and obtaining its image characteristics, a patch color arrangement means for setting a color patch color arrangement according to the image characteristics, and a setting by the patch color arrangement means A test chart output means for outputting a test chart based on the color patch to the image output device; a color measurement means for obtaining a color measurement value of a color patch in the test chart output from the image output device; and the color measurement Profile creating means for creating the profile based on the value.

  According to the present invention having the above-described configuration, the profile that realizes the optimum color reproduction for the reference image is created by optimizing the color patch color arrangement in the color chart according to the profile creation reference image. Can do.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings. The configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of an image printing system according to the present embodiment. In the figure, 101 is a control personal computer (hereinafter referred to as PC), 102 is a monitor or the like, an image display device for displaying an image, 103 is a printer or the like, and an image output device for printing out an image on a recording sheet. It is. Reference numeral 104 denotes a color chart that is printed out by the printer 103 on a recording sheet to be printed, that is, a test chart. Here, the image data for the test chart in the present embodiment is preferably data that allows the user to acquire color reproduction characteristics in a printing environment (printer model, paper type, etc.) that the user wants to execute printing. Reference numeral 105 denotes a colorimeter that performs colorimetry on an image formed on a recording sheet, and is also realized by an image input device such as a scanner that optically reads an image on the recording sheet.

  Reference numeral 106 denotes an image processing application for displaying and editing an image on the control PC 101. Reference numeral 107 denotes a printer driver for controlling and driving the printer 103 on the control PC 101. Reference numeral 108 denotes an OS (operating system) installed in the control PC 101.

  FIG. 5 shows an example of a print setting UI for making settings on the printer 103 side displayed by the printer driver 107 when the “print” button is selected from the menu screen displayed on the monitor 102 by the application 106. FIG. Hereinafter, a print setting operation when the user intends to print with higher accuracy will be described.

  The user of the printer 103 performs a series of operations such as pressing the print button 505 after selecting the paper type 502, the print quality 503, and the matching method 504 on the print setting screen 501 shown in FIG. Here, when the user wants to perform printing with higher accuracy, the print setting screen 501 is operated as follows. That is, after the user selects the paper type 502, the print quality 503, and the matching method 504, the user presses the new profile creation button 506. Then, a UI screen for setting conditions for profile creation is opened, and profile creation processing in this embodiment is started. Note that the profile creation process in the present embodiment is performed by the application 106.

  FIG. 2 is a flowchart showing profile creation processing in the present embodiment. First, in step S201, a reference image referred to for profile creation is acquired. The reference image acquisition method is not particularly limited. For example, a method for acquiring an image displayed on the monitor 102 as it is, a file name designation by a user, or a scanner (configured as a colorimeter 105 in this embodiment) is used. Reading, etc. can be considered. As the reference image, an image having a color that the user desires to be reproduced with high accuracy during printing should be adopted.

  In step S202, the reference image acquired in step S201 is analyzed to acquire its image characteristics. As an analysis method in this case, for example, a histogram of the reference image may be acquired to determine whether the reference image is monochrome or color. Further, it is conceivable to extract a representative color by histogram analysis, or to determine that the reference image is a person image when the representative color is a skin color, for example. It is also conceivable to determine which image / graphic / character or the like the image has based on the object attribute of the reference image.

  In step S203, a test chart is selected based on the image characteristics obtained as an analysis result in step S202. That is, the optimal color patch color scheme in the test chart is determined. Details of the chart selection process in step S203 will be described with reference to FIGS.

  FIG. 3 is a diagram illustrating an example of a test chart that is selected when it is determined by the analysis in step S202 that the reference image is a graphic PPT document. The test chart shown in FIG. 3 has the following three types of color patch groups. First, RGB data (RGB equidistant slice data) patches 301 that cover the entire color space are provided. Further, a color palette 302 often used as an office document such as a PPT document and a gradation patch 303 used in a style installed by default in the PPT document are arranged.

  Further, for example, when it is determined by the histogram analysis in step S202 that blue gradation data is used in the reference image, a test chart as shown in FIG. 4 is selected. The test chart shown in FIG. 4 has gradation data 403 in which a plurality of colors in the blue gradation color gamut are arranged as color patches. Reference numeral 401 denotes an RGB patch for the entire color space. Further, when a characteristic representative color is detected by histogram analysis, a representative color patch 402 is provided in which a plurality of color patches are arranged in the vicinity of the representative color.

  As described above, when the test chart having the optimum patch color scheme is selected in step S203, the selected test chart is printed by the printer 103 in step S204, and the test chart output 104 is printed on the recording medium. Get. In step S205, the test chart output 104 is measured using the colorimeter 105.

  Next, in step S206, based on the analysis result of the reference image in step S202, lattice point positions in the color space constituting the LUT of the profile to be created are set. Hereinafter, the lattice point setting process in the present embodiment will be described in detail with reference to FIGS. 6 and 7.

  FIG. 6 is a diagram showing a grid point arrangement example of a general profile in which the RGB values are changed uniformly by 16 steps. FIG. 7 is a diagram illustrating an example of profile lattice point arrangement when it is determined as a result of the analysis in step S202 that blue gradation is frequently used in the reference image. Comparing the grid point arrangements of FIG. 6 and FIG. 7, it can be seen that the grid point information corresponding to the blue gradation is arranged more densely than other colors in FIG. Of course, in addition to the gradation image, if the color frequently used in the reference image, that is, the representative color is found based on the analysis result in step S202, the lattice point arrangement is made so that the lattice points near the representative color are dense. It is determined.

  In the following, an example is shown in which a good print result can be obtained by devising the arrangement of lattice points. For example, when the reference image is a monochrome image, a color patch having a hue used in a sepia tone or a monocolor image is arranged. Specifically, with respect to RGB values ranging from 0 to 128, grid points are arranged at 9-step intervals, or only achromatic grid points are arranged. Further, for example, when the reference image is a landscape image, the blue color of the sky and the green color of the grass are regarded as important. Therefore, a test chart in which RGB values of bright blue color and calm green color are arranged. Further, for example, when the reference image is a person image, the skin color of the person is regarded as important. Therefore, RGB values representing the skin color (skin color neighboring colors, for example, RGB values that satisfy R> G, B) are arranged.

  For example, if the reference image is found to be an office document by the object information analysis in step S202, a color palette 302 that is set as default for the office document is displayed in the test chart as shown in FIG. It is good to arrange in.

  As described above, when the optimum grid point position of the profile is set in step S206, in step S207, a profile that enables high-precision color reproduction for the reference image is set for the set grid point position. create. At this time, it goes without saying that the colorimetric values acquired in step S205 are referred to.

  Note that in the profile creation process of the present embodiment, the setting contents of the paper type 502, the print quality 503, and the matching method 504 selected by the user on the print setting screen 501 shown in FIG. 5 are also referred to. Of course.

  As described above, according to the present embodiment, the color arrangement of the color patches in the test chart for acquiring printer characteristics is optimized according to the reference image having the color desired by the user. As a result, it is possible to create a profile that can reproduce a color desired by the user with high accuracy.

<Other embodiments>
Although the embodiment has been described in detail above, the present invention can take an embodiment as a system, apparatus, method, program, recording medium (storage medium), or the like. Specifically, the present invention may be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, an imaging device, a web application, etc.), or may be applied to a device composed of a single device. good.

  In the present invention, a software program for realizing the functions of the above-described embodiments is supplied directly or remotely to a system or apparatus, and the computer of the system or apparatus reads and executes the supplied program code. Is also achieved. The program in this case is a computer-readable program that corresponds to the flowchart shown in the drawing in the embodiment.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, or the like.

  Recording media for supplying the program include the following media. For example, floppy disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD- R).

  As a program supply method, the following method is also possible. That is, the browser of the client computer is connected to a homepage on the Internet, and the computer program itself (or a compressed file including an automatic installation function) of the present invention is downloaded to a recording medium such as a hard disk. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the present invention.

  In addition, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, distributed to users, and key information for decryption is downloaded from a homepage via the Internet to users who have cleared predetermined conditions. It is also possible to make it. That is, the user can execute the encrypted program by using the key information and install it on the computer.

  Further, the functions of the above-described embodiments are realized by the computer executing the read program. Furthermore, based on the instructions of the program, an OS or the like running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments can also be realized by the processing.

  Further, the program read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, and then executed, so that the program of the above-described embodiment can be obtained. Function is realized. That is, based on the instructions of the program, the CPU provided in the function expansion board or function expansion unit can perform part or all of the actual processing.

1 is a block diagram illustrating a configuration of an image printing system according to an embodiment of the present invention. It is a flowchart which shows the profile creation process in this embodiment. It is a figure which shows the example of a test chart in this embodiment. It is a figure which shows the example of a test chart in this embodiment. FIG. 6 is a diagram illustrating an example of a printer driver setting UI according to the present embodiment. It is a figure which shows the example of a grid point arrangement | positioning of a general profile. It is a figure which shows the grid point arrangement | positioning example of the profile in this embodiment.

Claims (12)

An image processing system that performs color conversion based on a profile on an input image in an image processing apparatus and outputs the image after the color conversion from an image output apparatus, wherein the image processing apparatus includes:
An image input means for inputting a reference image for profile creation;
Analyzing means for analyzing the reference image and obtaining image characteristics thereof;
Patch color arrangement means for setting the color patch color arrangement according to the image characteristics;
Test chart output means for causing the image output device to output a test chart with color patches set by the patch color arrangement means;
Colorimetric means for obtaining colorimetric values of color patches in the test chart output from the image output device;
Profile creation means for creating the profile based on the colorimetric value;
An image processing system comprising:   The image processing system according to claim 1, wherein the analysis unit acquires the image characteristics by analyzing a histogram of the reference image.   3. The image processing according to claim 2, wherein the patch color arrangement unit arranges a plurality of colors in the gradation color gamut as the color patch when a gradation color gamut is detected as the image characteristic in the analysis unit. system.   3. The image processing according to claim 2, wherein the patch color arrangement unit arranges a plurality of colors in the vicinity of the representative color as the color patch when the analysis unit detects a representative color as the image characteristic. 4. system.   5. The image processing system according to claim 4, wherein the patch color arrangement unit arranges a plurality of colors in the vicinity of the skin color as the color patch when the representative color detected by the analysis unit is a skin color.   3. The image according to claim 2, wherein the patch color arrangement unit arranges an achromatic color as the color patch when the analysis unit acquires that the reference image is a monochrome image as the image characteristic. Processing system.   The image processing system according to claim 1, wherein the analysis unit acquires the image characteristics by analyzing object information of the reference image.   The patch color arrangement unit sets a default color palette for an office document as the color patch when the analysis unit acquires that the reference image is an office document as the image characteristic. Item 8. The image processing system according to Item 7.   The image processing system according to claim 1, wherein the profile creation unit sets a grid point position on a color space constituting the profile in accordance with the image characteristics. A control method of an image processing system that performs color conversion based on a profile on an input image in an image processing apparatus and outputs the image after the color conversion from an image output apparatus, wherein the image processing apparatus includes:
An image input step in which the image input means inputs a reference image for profile creation;
An analyzing step for analyzing the reference image and acquiring the image characteristics;
A patch coloring step for setting a color patch coloring according to the image characteristics;
Test chart output means, a test chart output step for causing the image output device to output a test chart based on the color patches set in the patch coloration step;
A colorimetric step, wherein the colorimetric means acquires a colorimetric value of a color patch in the test chart output from the image output device;
A profile creating step for creating a profile based on the colorimetric value;
A control method for an image processing system, comprising:   A computer program that, when executed by a computer, causes the computer to function as the image processing apparatus according to any one of claims 1 to 9.   A computer-readable recording medium having recorded thereon the computer program according to claim 11.

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