JP2007081735A - Image processor, method, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To readily adjust color appearance parameters, in a color-matching processing between two different devices. <P>SOLUTION: An image processor comprises an output control means for outputting an image for adjustment from an image output device; a colorimetric result acquiring means for acquiring the colorimetric result of the image for adjustment which is outputted from the image output device; a color converting means for converting the colorimetric result into display color information for an image display device by using the appearance parameter; a display control means for allowing the image display device to perform displaying, based on the display color information; and an adjusting means for adjusting the appearance parameter, based on the adjustment indication of the appearance parameter from the user, on the basis of the outputted image for adjustment and displaying in the image display device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a color matching technique, and more particularly to a technique for performing color matching of images displayed / output on different devices such as a monitor and a printer.

［数式２］

［数式３］

さらに、デバイス間の白色基準が異なる場合には、それを補正するため、色順応の式を用い、白色基準の相違を補正している。例えば、内蔵されたセンサにより画像観察環境の白色情報等を測定し、色順応変換式を用いて画像信号を補正する方法が提案されている（特許文献１を参照。）。
特開平１０−７０６５３号公報 Conventionally, when color matching between different devices such as a monitor and a printer is performed, XYZ three are obtained using [Equation 1] for a light source color such as a monitor and [Equation 2] for an object color such as a printed matter. Find the stimulus value. Further, after obtaining the CIELab value using [Equation 3], color reproduction is performed so that the monitor display color matches the Lab value of the printed color.
[Formula 1]

[Formula 2]

[Formula 3]

Furthermore, when the white reference between devices differs, in order to correct it, the difference of the white reference is corrected using a chromatic adaptation formula. For example, a method has been proposed in which white information or the like of an image observation environment is measured by a built-in sensor, and an image signal is corrected using a chromatic adaptation conversion formula (see Patent Document 1).
JP-A-10-70653

  However, as in the proposed method, when the visual chromatic adaptation is corrected using only measurement data obtained by a built-in sensor or the like as an observation environment, sufficient accuracy may not be obtained. For example, in the case of so-called monitor matching, in which a monitor display image (current image) is output by a printer (reproduced image) and compared with each other, color adaptation correction using only measured data is used as an image observation environment. There is a problem that the "appearance" does not match.

  This is due to the following reasons. When comparing images between different devices such as a monitor and a printer, first, the “appearance” of the monitor display image is influenced by the printer observation image in addition to the monitor white point, the illumination light source, and the observation environment. Conversely, the “appearance” of the printer output image is also affected by the monitor observation image in addition to the printer white point, illumination light source, and observation environment. As described above, when the monitor or the printed matter is observed individually, and when the two are compared, the “appearance” of the color may be different.

  That is, the adaptation state of the human eye when comparing the monitor image with the printed matter is different from the case of observing the image on the monitor or the printed matter alone. Therefore, in the conventional color adaptation model that does not take this into consideration, there arises a problem that the color appearances of the monitor display image and the printer print image do not match.

  Therefore, an object of the present invention is to make it possible to easily adjust a color appearance parameter in a color matching process between two different devices.

  In order to solve the above problems, the present invention provides an output control unit that outputs an adjustment image from an image output device, and a color measurement result acquisition that acquires a result of color measurement of the adjustment image output from the image output device. Means, color conversion means for converting a colorimetric result into display color information for an image display apparatus using appearance parameters, and display control means for causing the image display apparatus to perform display based on the display color information. And adjusting means for adjusting the appearance parameter based on an instruction for adjusting the appearance parameter from a user based on the output adjustment image and the display on the image display device.

  The present invention for solving the above problems further includes an output control means for outputting an adjustment image from the image output apparatus, a calculation means for calculating output color information of the adjustment image output from the image output apparatus, Color conversion means for converting the output color information into display color information for an image display device using an appearance parameter, display control means for causing the image display device to perform display based on the display color information, and And adjusting means for adjusting the appearance parameter based on an instruction to adjust the appearance parameter from a user based on the output adjustment image and the display on the image display device.

  According to the present invention, it is possible to easily adjust the color appearance parameter in the color matching process between two different devices.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

[First Embodiment]
Hereinafter, a first embodiment will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of an image processing apparatus corresponding to the first embodiment. In FIG. 1, reference numeral 1 denotes an image processing apparatus corresponding to this embodiment. Reference numeral 2 denotes an image display device as a monitor for image display, such as a CRT monitor or a liquid crystal monitor. Reference numeral 3 denotes an image display control unit for controlling image display in the image display device 2. Reference numeral 4 denotes an image output device for printing out an image, such as an ink jet printer or a laser printer. Reference numeral 5 denotes an image output control unit for controlling the print output of the image in the image output apparatus 4.

  A color measuring device 6 measures the color of the patch image printed out by the image output device 4. An appearance parameter adjusting unit 7 adjusts an appearance parameter used to calculate the “appearance” of the color when observing the image displayed on the image display device 2 and the image printed out by the image output device 4. . An appearance parameter storage unit 8 stores the appearance parameter adjusted by the appearance parameter adjustment unit 7. A profile storage unit 9 stores device profiles of the image display device 2 and the image output device 4. Reference numeral 10 denotes an LUT creation unit that creates an LUT by using the appearance parameter stored in the appearance parameter storage unit 8 and the device profile stored in the profile storage unit 9.

  Reference numeral 11 denotes an LUT storage unit that stores the LUT created by the LUT creation unit 10. A color conversion unit 12 performs color conversion of input data using the appearance parameter stored in the appearance parameter storage unit 8 or the LUT stored in the LUT storage unit 11. An image data input unit 13 reads image data into the image processing apparatus 1. An image data storage unit 14 stores image data, such as a hard disk or a CD-ROM.

<Overall processing>
Next, an image input / output process corresponding to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart illustrating an example of image input / output processing corresponding to the present embodiment performed in the image processing apparatus 1.

  2, in S201, the image output device 4 prints out a parameter adjustment patch (details will be described later). Next, in step S <b> 202, the color measurement device 6 performs color measurement on the parameter adjustment patch printed out in step S <b> 201. In step S203, an initial value set as a default is set as the appearance parameter. In step S204, the patch colorimetric values measured by the colorimetric device 6 are color-converted by the color conversion unit 12 using the appearance parameters stored in the appearance parameter storage unit 8, and are displayed on the monitor. Is calculated (details will be described later).

Subsequently, in step S205, the image display control unit 3 controls the image display device 2 to display the monitor display color calculated in step S204.
In step S206, a determination is received from the user as to whether the color of the parameter adjustment patch printed out in step S201 matches the color of the monitor display patch displayed in step S205. If the determination that the user matches is received (“YES” in step S206), the process proceeds to step S208. On the other hand, when it is determined that they do not match (“NO” in step S206), the process proceeds to step S207.

  First, in step S207, a UI as shown in FIG. 3 is displayed on the image display device 2, and a readjustment of an appearance parameter considering the color shift at the time of comparison in step S206 is received from the user.

  On the other hand, in step S208, the appearance parameter when it is determined in step S206 that the color of the printed matter and the monitor display matches is stored in the appearance parameter storage unit 8. In step S209, the LUT creation unit 10 reads the device profiles of the image display device 2 and the image output device 4 from the profile storage unit 9.

  In step S210, the LUT creation unit 10 creates an LUT using the device profile read in step S208 and the appearance parameter stored in the appearance parameter storage unit 8. In step S211, the image input unit 13 reads the image data stored in the image data storage unit 14 into the image processing apparatus 1. In step S212, the color conversion unit 12 performs color conversion on the image data read in step S211 using the LUT stored in the LUT storage unit 11. In step S213, the image output controller 5 outputs the image color-converted in step S212 from the image output device 4.

  Details of the processing in each step of FIG. 2 will be described below.

<Parameter adjustment patch>
The parameter adjustment patch output in step S201 can be, for example, gray scale and primary / secondary color primary. However, the patches are not limited to these. For example, when the user attaches importance to the portrait color reproduction accuracy, a change such as adding a skin color region patch may be performed.

  That is, the patch configuration is not particularly limited as long as the parameters can be adjusted while sufficiently confirming the color area to be output by the user.

<Monitor display color calculation>
Next, the monitor display color calculation process in step S204 will be described. In step S204, a monitor display color is calculated such that the colorimetric value (for example, XYZ tristimulus values) of the printed material matches the color “appearance”. Many chromatic adaptation conversion formulas that take color “appearance” into account have been reported. Here, the CIECAM02 conversion formula reported by the International Illumination Commission (CIE) will be described as an example.

Measured in step S202, the patch colorimetric values of printed matter _{(X P, Y P, Z} P) When, set appearance parameters at step _{S203 (X W, Y W,} Z W, L A , c, N _c , F, Y _b ) can be converted into tristimulus values (X _M , Y _M , Z _M ) of the monitor display color. Thereafter, the device profile for the image display device 2 as a monitor stored in the profile storage unit 9 is used to convert the device RGB values of the monitor. This makes it possible to obtain monitor display RGB values that have the same color “look” as the printed patch.

  In the above description, the CIECAM02 conversion formula is used for the chromatic adaptation conversion formula. However, the conversion formula applicable to the invention corresponding to the present embodiment is not limited to this. For example, the type of conversion formula to be applied is not limited as long as it is a conversion formula that can satisfy the accuracy required by the user, such as a chromatic adaptation formula of Von Kries.

<Appearance parameter adjustment user interface>
FIG. 3 is a diagram illustrating an example of a UI used when adjusting the appearance parameter in step S206. In FIG. 3, reference numeral 301 denotes a patch image display area for displaying the monitor display color calculated in step S204 for confirmation by the user. An appearance parameter display area 302 displays the numerical values of the default appearance parameters of the image display device 2 and the image output device 4 set in step S203 and the numerical values of the appearance parameters of the image display device 2 adjusted by the user. It is.

303, white spots appearance parameter _{(X W, Y W, Z} W) chromaticity calculated from (x _W, y _W), and the luminance, a region further for displaying the partial adaptation ratio. Reference numeral 304 denotes a chromaticity coordinate display area in which the chromaticity of the appearance parameter is plotted. Here, the default white point of the image output device 4 (printer default white point), the default white point of the image display device 2 (monitor default white point), and the white point adjusted for the image display device 2 (monitor adjustment) (White point) is shown.

The user not only directly adjusts the appearance parameters (X _W , Y _W , Z _W , L _A , c, N _c , F, Y _b ), but also checks the chromaticity coordinates 304 while (x _W , y _W ) can be adjusted. In addition, the optimum appearance parameter can be determined while adjusting the partial adaptation ratio. Here, the partial adaptation ratio is a value that indicates how much the human eye adapts to the monitor and the printed matter.

<LUT creation>
Next, the LUT creation process in step S210 will be described. In general, a color reproduction range (hereinafter referred to as a color gamut) of a monitor such as the image display device 2 expressed by a light source color and a color gamut of a printer such as the image output device 4 expressed by an object color are: Its shape is different. The chromatic adaptation correction from step S204 to step S207 is to match the “color appearance” and does not consider the difference in the color gamut shapes of different devices. Therefore, after the color printed out by the image output device 4 is converted into a corresponding color displayed on the image display device 4 by chromatic adaptation correction, colors outside the color gamut of the monitor are subjected to color gamut compression processing called gamut mapping. Must be converted to a color in the monitor's color gamut.

  In general, color gamut compression processing called colorimetry is used in order to maintain the color appearance as much as possible even when color gamut compression is performed. FIG. 4 is a diagram for explaining the concept of color gamut compression processing by general colorimetry. In FIG. 4, 401 indicates the color gamut of the monitor (image display apparatus 2), and 402 indicates the color gamut of the printer (image output apparatus 4). Reference numeral 403 denotes a point within the monitor color gamut 401 and outside the printer color gamut 402, and this is a mapping target in the color gamut compression processing. Reference numeral 404 denotes a point after mapping from the monitor color gamut 401 to the printer color gamut 402. Reference numeral 405 denotes an overlapping range of the monitor color gamut 401 and the printer color gamut 402, and the colors included in this range are maintained.

  As described above, even in the monitor color gamut 401, the input value is held for the point in the printer color gamut 402, and the point outside the printer color gamut 402 is the closest point to the core outside the color gamut. Converted.

  In the color gamut compression processing, color gamut compression processing is performed on representative points in the monitor color gamut 401 (for example, 729 points each consisting of a combination of 9 grid intervals for RGB) to obtain a mapped color value. For input points other than the representative points, interpolation processing (for example, tetrahedral interpolation) is performed from the color values after mapping of the representative points to obtain mapping color values.

  Note that the type of color gamut compression method is not limited to the above colorimetric method, and is not limited as long as it is a method for converting a color outside the color gamut into a point within the color gamut.

  According to the present embodiment, in the color matching process between two different devices, even when the image is observed with each device alone and the adaptation state is different, parameter adjustment is easily performed to obtain a good color matching result. Obtainable. Specifically, as parameter adjustment for obtaining a good color matching result, it is only necessary to adjust appearance parameters so that the “appearance” of colors is equal for several patches.

[Second Embodiment]
Next, a second embodiment will be described in detail with reference to the drawings. FIG. 5 is a block diagram showing an example of the configuration of an image processing apparatus corresponding to the second embodiment. In FIG. 5, reference numeral 501 denotes an image processing apparatus corresponding to this embodiment. Reference numeral 502 denotes an image display device as a monitor for image display such as a CRT monitor or a liquid crystal monitor. Reference numeral 503 denotes an image display control unit for controlling image display in the image display device 502. Reference numeral 504 denotes an image output device for printing out an image, such as an ink jet printer or a laser printer. Reference numeral 505 denotes an image output control unit for controlling print output of an image in the image output apparatus 504.

  An appearance parameter adjustment unit 506 adjusts an appearance parameter used when calculating the “appearance” of the color in order to observe the image displayed on the image display device 502 and the image printed out by the image output device 504. . An appearance parameter storage unit 507 stores the appearance parameter adjusted by the appearance parameter adjustment unit 506. A profile storage unit 508 stores device profiles of the image display device 502 and the image output device 504. Reference numeral 509 denotes an LUT creation unit that creates an LUT using an appearance parameter stored in the appearance parameter storage unit 507 and a device profile stored in the profile storage unit 508.

  Reference numeral 510 denotes an LUT storage unit that stores the LUT created by the LUT creation unit 509. A color conversion unit 511 performs color conversion of input data using the appearance parameter stored in the appearance parameter storage unit 507 or the LUT stored in the LUT storage unit 510. An image data input unit 512 reads image data into the image processing apparatus 501. An image data storage unit 513 stores image data, such as a hard disk or a CD-ROM.

<Overall processing>
Next, an image input / output process corresponding to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing an example of image input / output processing corresponding to the present embodiment performed by the image processing apparatus 501.
First, in step S601, the image output device 504 prints out a parameter adjustment image. Next, in step S602, the print color of the parameter adjustment image printed out in step S601 is calculated using the printer profile stored in the profile storage unit 508.

  In step S604, the print color of the image calculated in step S602 is color-converted by the color conversion unit 511 using the appearance parameter stored in the appearance parameter storage unit 507, which is the same as in the first embodiment. Similarly, the monitor display color is calculated. In step S605, the monitor display color calculated in step S604 is displayed on the image display device 502 in the image display unit 503.

  In step S606, a determination is made from the user as to whether or not the color of the parameter adjustment image printed out in step S601 matches the color of the monitor display image displayed in step S205. If the determination that the user matches is received (“YES” in step S606), the process proceeds to step S608. On the other hand, when it is determined that they do not match (“NO” in step S606), the process proceeds to step S607.

  First, in step S607, a UI as shown in FIG. 3 is displayed on the image display device 502 in the same manner as in the first embodiment, and a readjustment of an appearance parameter taking into account the color shift at the time of comparison in step S606 is received from the user. .

  On the other hand, in step S608, the appearance parameter when it is determined in step S606 that the printed matter and the monitor display color match is stored in the appearance parameter storage unit 507. In step S609, the LUT creation unit 509 reads the device profiles of the image display device 502 and the image output device 504 from the profile storage unit 508.

  In step S610, the LUT creation unit 509 creates an LUT using the device profile read in step S608 and the appearance parameters stored in the appearance parameter storage unit 507. In step S <b> 611, the image input unit 512 reads image data stored in the image data storage unit 513 into the image processing apparatus 501. In step S612, the color conversion unit 511 performs color conversion on the image data read in step S611 using the LUT stored in the LUT storage unit 510. In step S613, the image output control unit 505 outputs the image color-converted in step S612 from the image output device 504.

<Parameter adjustment image>
The parameter adjustment image output in step S601 of the present embodiment will be described. In the first embodiment, a patch image is formed by the image output device 4, and appearance parameters are adjusted while confirming color reproduction of the patch image. On the other hand, in this embodiment, it is possible to adjust the appearance parameter while confirming the color reproduction of a desired natural image. That is, the user can select an image he / she wants to output and adjust appearance parameters based on the image.

  Note that the UI used in the second embodiment is almost the same as the UI shown in FIG. 3, and instead of displaying a patch in the patch image display area 301, a natural image is displayed.

  According to the present embodiment, in the color matching process between two different devices, even when the image is observed with each device alone and the adaptation state is different, parameter adjustment is easily performed to obtain a good color matching result. Obtainable. Specifically, as a parameter adjustment for obtaining a good color matching result, it is only necessary to adjust the appearance parameter so that the “appearance” of the colors is equal for a desired natural image.

[Other Embodiments]
In the first and second embodiments described above, a monitor is taken as an example of the image display device (2, 502), and a printer is taken as an example of the image output device (4, 504). However, such an apparatus is not limited to these devices. For example, a projector may be used as the image display device.

  Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), and a device (for example, a copying machine and a facsimile device) including a single device. You may apply to.

  The object of the present invention can also be achieved by supplying a storage medium storing software program codes for realizing the above-described functions to the system, and the system reading and executing the program codes. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. In addition, an operating system (OS) running on a computer performs part or all of actual processing based on an instruction of the program code, and the above-described functions are realized by the processing.

  Furthermore, you may implement | achieve with the following forms. That is, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Then, based on the instruction of the program code, the case where the above-described functions are realized by the CPU included in the function expansion card or the function expansion unit performing part or all of the actual processing is also included.

It is a block diagram which shows an example of a structure of the image processing apparatus corresponding to 1st Embodiment. 3 is a flowchart showing a flow of processing in the image processing apparatus corresponding to the first embodiment. It is a figure which shows an example of the user interface for adjusting an appearance parameter corresponding to 1st Embodiment. It is a figure for demonstrating the color gamut compression method by the colorimetry corresponding to 1st Embodiment. It is a block diagram which shows an example of a structure of the image processing apparatus corresponding to 2nd Embodiment. 10 is a flowchart showing a flow of processing in an image processing apparatus corresponding to the second embodiment.

Claims (8)

Output control means for outputting an adjustment image from the image output device;
Colorimetric result acquisition means for acquiring a result of colorimetric measurement of the adjustment image output from the image output device;
Color conversion means for converting the colorimetric results into display color information for an image display device using appearance parameters;
Display control means for causing the image display device to perform display based on the display color information;
An image processing apparatus comprising: adjusting means for adjusting the appearance parameter based on an adjustment instruction for the appearance parameter from a user based on the output adjustment image and the display on the image display device. Output control means for outputting an adjustment image from the image output device;
Calculation means for calculating output color information of the adjustment image output from the image output device;
Color conversion means for converting the output color information into display color information for an image display device using appearance parameters;
Display control means for causing the image display device to perform display based on the display color information;
An image processing apparatus comprising: adjusting means for adjusting the appearance parameter based on an adjustment instruction for the appearance parameter from a user based on the output adjustment image and the display on the image display device.   3. The adjustment parameter according to claim 1, wherein the adjustment unit receives an instruction to adjust the appearance parameter such that the output adjustment image and the display on the image display device match each other. Image processing device.   The image processing apparatus according to claim 1, wherein the color conversion unit performs the conversion using a CIECAM or Von Kries conversion formula. An output control step of outputting an adjustment image from the image output device;
A colorimetric result acquisition step of acquiring a result of colorimetric measurement of the adjustment image output by the image output device;
A color conversion step of converting the color measurement result into display color information for the image display device using the appearance parameter;
A display control step for causing the image display device to perform display based on the display color information;
An adjustment step of adjusting the appearance parameter based on an adjustment instruction of the appearance parameter from a user based on the output adjustment image and the display on the image display device. Method. An output control step of outputting an adjustment image from the image output device;
A calculation step of calculating output color information of the adjustment image output from the image output device;
A color conversion step of converting the output color information into display color information for an image display device using an appearance parameter;
A display control step for causing the image display device to perform display based on the display color information;
An adjustment step of adjusting the appearance parameter based on an adjustment instruction of the appearance parameter from a user based on the output adjustment image and the display on the image display device. Method.   A computer program for causing a computer to function as the image processing apparatus according to claim 1.   A computer-readable storage medium storing the computer program according to claim 7.

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