JP2011116129A - Color processing apparatus and method therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manage a creation history of a profile of an output device created before proofing when printing an image subjected to color conversion in accordance with output characteristics of a target printing machine by a copy machine or a printer for the proofing. <P>SOLUTION: An operator sets whether parameters (storage location and profile name) about the storage of a file and color measurement values are saved or not, and whether history control information is saved or not. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a color processing apparatus and method.

  In the color reproduction process of printers and printing presses, as a method of color correction to improve the color reproduction effect, the input color space is obtained by color masking that performs matrix operation on the input color space data to obtain the output color space data. There are many methods for converting the above data into output color space data.

  However, the output characteristics of color printers and printing presses exhibit strong nonlinearity. Therefore, a global method such as the color masking method, that is, a color correction method in which changing the elements of the matrix affects the entire output color space sufficiently approximates the characteristics of the color printer or printing machine in all color gamuts. I can't do it.

Japanese Patent Laid-Open No. 8-102856 JP 2000-298531 A JP 2001-026170 A Japanese Patent Laid-Open No. 9-1881879

  It is an object of the present invention to provide a profile that accurately approximates the strong nonlinear output characteristics of color printers and printing presses and enables high-precision color reproduction, and to manage the creation history of the created profile. And

  Another object is to manage the colorimetric values used for creating the profile.

  The present invention has the following configuration as one means for achieving the above object.

  The color processing according to the present invention obtains a colorimetric value obtained by measuring the color chart output from the output device based on the colorimetric conditions, and creates a profile using the obtained colorimetric value. A profile of the output device is created based on the conditions of the above, the created profile is stored, and the colorimetric light source and colorimetric field that are the colorimetric conditions, and the creation conditions are independent of the profile. It is characterized by storing.

  Preferably, the acquired colorimetric value is stored.

  According to the present invention, it is possible to accurately approximate the strong nonlinear output characteristics of color printers and printing presses, provide a profile that enables highly accurate color reproduction, and manage the creation history of the created profile. Can do.

  In addition, the colorimetric values used for creating the profile can be managed.

1 is a block diagram illustrating a configuration example of an image processing apparatus according to Embodiment 1. FIG. The figure which shows an example of a RGB-> Lab conversion table. The flowchart which shows the procedure which obtains the correspondence of device RGB value ⇔Lab colorimetric value, and performs device RGB → Lab conversion. The figure which shows an example of a sample image. FIG. 6 is a diagram illustrating an example of a color measurement result by a color patch color measurement unit. The figure explaining selection of a sample point. The figure explaining the weighting function according to the distance d. The figure explaining the function which changes the number of sample points. FIG. 3 is a block diagram illustrating a configuration example of an image processing apparatus according to a second embodiment. FIG. 4 is a block diagram illustrating a configuration example of an image processing apparatus according to a third embodiment. FIG. 10 is a block diagram illustrating a configuration example of a color conversion module according to a fourth embodiment. FIG. 12 is a diagram showing a color conversion procedure executed by the CMM shown in FIG. FIG. 13 is a diagram showing an example of a preview screen displayed on the monitor shown in FIG. The flowchart which shows a colorimetry procedure. The figure which shows an example of the user interface in a colorimetry process. The figure which shows an example of the user interface in a colorimetry process. The figure which shows an example of the user interface in a colorimetry process. The figure which shows an example of the user interface in a colorimetry process. The figure which shows an example of the user interface in a colorimetry process. The figure which shows an example of the user interface which displays a colorimetry result. The figure which shows the example of a table in which a standard colorimetric value is stored. The figure explaining the creation procedure of a target profile. The flowchart which shows the smoothing procedure of a colorimetric value. The figure which shows an example of the parameter setting screen displayed when creating the profile of a target. The figure which shows an example of the parameter setting screen displayed when creating the profile of a target. 6 is a flowchart illustrating an example of a procedure for storing a profile, colorimetric values, and history management information. The figure which shows an example of the user interface regarding log | history management. The figure which shows an example of the user interface regarding log | history management. The figure which shows an example of the user interface regarding log | history management. The figure which shows an example of the user interface regarding log | history management. The figure which shows the list example of the colorimetric value preserve | saved. The figure which shows an example of the log | history management information preserve | saved. The figure which shows the concept of profile re-creation time. The flowchart which shows the process example for estimating and warning about profile re-creation time. The figure which shows the warning display example of profile re-creation. The figure which shows the example of a display of a color difference fluctuation | variation. The conceptual diagram which shows the method of managing project DB and colorimetric value DB. The figure which shows the structural example of a profile. The figure which shows the example of a display of a login screen. The figure which shows the example of a project table stored in project DB. The figure which shows the example of a measurement table stored in colorimetric value DB.

  Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Constitution]
FIG. 1 is a block diagram illustrating a configuration example of an image processing apparatus according to an embodiment.

  The signal input to the image processing apparatus shown in FIG. 1 is an image signal in a color space depending on some device, for example, an RGB signal indicating an image read from a document by a scanner, or output to a printer. It may be a CMYK signal. When this embodiment is applied to a copying machine, the input signal is an RGB signal indicating an image read by a scanner. Further, when the purpose is proof (test printing, proof printing), it is a CMYK signal output to the target printing machine.

  Such an input signal is input to the input color → Lab conversion unit 101 and converted into a signal in the Lab color space, which is a color space independent of the device. This conversion is realized by LUT conversion using the input color → Lab conversion LUT 102.

  In the table of input color → Lab conversion LUT 102, a table corresponding to the color space of the input signal needs to be set. For example, if an image signal that depends on the RGB color space of scanner A is input, 3D input representing the correspondence between the RGB value dependent on the RGB color space of scanner A and the Lab value-RGB of 3D output → Lab The conversion table is set as a table of input color → Lab conversion LUT102. Similarly, when an image signal subordinate to the CMYK color space of the printer B is input, CMYK → Lab of four-dimensional input-three-dimensional output indicating the correspondence between the CMYK value subordinate to the color space of the printer B and the Lab value The conversion table is set as a table of input color → Lab conversion LUT102.

  FIG. 2 is a diagram showing an example of an RGB → Lab conversion table, and shows the correspondence between 8-bit RGB values and Lab values, respectively. Since an actual table stores Lab values that have representative RGB values as addresses, the input color → Lab conversion unit 101 extracts Lab values near the input RGB values from the table, and extracts the extracted Lab values. The Lab value corresponding to the input RGB value is obtained by performing an interpolation operation on the value.

  The Lab signal output from the input color → Lab conversion unit 101 is converted into a signal in the device RGB color space by the Lab → device RGB conversion unit 104 based on the device RGB → Lab conversion LUT 105. Details of this conversion processing will be described later.

  Here, when the color space of the input signal is the RGB color space, the color gamut is often wider than the color gamut of the printer. Therefore, the Lab signal output from the input color → Lab conversion unit 101 is mapped (gamut mapping) to the color reproduction range of the printer 107 in the color space compression conversion unit 103 and then input to the Lab → device RGB conversion unit 104. Shall. As a specific method of gamut mapping, a method of performing color space compression processing in a uniform color space disclosed in JP-A-8-130655 may be used.

A device RGB color space signal output from the Lab → device RGB conversion unit 104 is converted into a CMYK color space signal subordinate to the printer 107 by the device RGB → CMYK conversion unit 106 and then sent to the printer 107. There are various methods for RGB → CMYK conversion, and any method may be used. For example, the following conversion formula is used.
C = (1.0-R)-K
M = (1.0-G)-K
Y = (1.0-B)-K
K = min {(1.0-R), (1.0-G), (1.0-B)}

[Lab → Device RGB conversion]
Next, details of the Lab → device RGB conversion unit 104 will be described.

  The Lab → device RGB conversion unit 104 converts the signal based on the correspondence between the device RGB value and the Lab colorimetric value obtained in advance. FIG. 3 is a flowchart showing a procedure for performing Lab → device RGB conversion by obtaining the correspondence between device RGB value and Lab colorimetric value. Of course, if the correspondence between the RGB values and Lab colorimetric values is already obtained, steps S1 and S2 are omitted.

● Step S1
The color patch generation unit 108 generates a sample image composed of a plurality of color patches as shown in FIG. Then, the generated RGB signal of the sample image is output to the printer 107 through the device RGB → CMYK conversion unit 106 to obtain the sample image 109.

  The sample image generated by the color patch generation unit 108 is created so as to equally divide the device RGB color space. In the example of FIG. 4, the RGB color space of 8 bits for each RGB is equally divided into 9 × 9 × 9 to obtain 729 patches. Originally, the color space subordinate to the printer 107 is the CMYK color space, but the RGB color space is subordinate to the printer 107 in the sense that it can be converted to the CMYK color space according to the conversion rule from the RGB color space. I think.

● Step S2
Each color patch of the obtained sample image 109 is measured by the color patch colorimetric unit 110 to obtain Lab colorimetric values for each color patch. The obtained Lab colorimetric values are distributed in the Lab color space as shown in FIG. By this operation, the RGB values generated by the color patch generation unit 108 and the Lab colorimetric values measured by the color patch colorimetry unit 110 are obtained, and a table of device RGB → Lab conversion LUT 105 can be obtained. . Using this device RGB → Lab conversion LUT 105, Lab → device RGB conversion is performed.

  By the way, when the LUT is used, a well-known technique such as interpolation or tetrahedral interpolation is used. In these interpolation calculations, the grid corresponding to the input side of the LUT needs to be equally spaced. The device RGB values in the device RGB → Lab conversion LUT 105 table are evenly arranged, but the Lab colorimetric values are not evenly arranged. For this reason, when an Lab value is input, the table of device RGB → Lab conversion LUT 105 does not constitute an LUT having an equally spaced grid. Therefore, it is not possible to simply perform an interpolation operation for inputting Lab values. Therefore, Lab → device RGB conversion is performed according to the following procedure.

● Step S3
The distance d (equivalent to the color difference based on the Lab color difference formula) between the Lab value included in the device RGB → Lab conversion LUT 105 table and the input Lab value is calculated and stored in the memory.

● Step S4
As shown in FIG. 6, N entries (●) are selected in ascending order of distance d with respect to the input Lab value (◎). At this time, the distance d is expressed as follows in ascending order.
RGB value │Lab colorimetric value │Distance ───┼─────┼──
RGB ₁ │ Lab ₁ │ d ₁
RGB ₂ │ Lab ₂ │ d ₂
RGB ₃ │ Lab ₃ │ d ₃
: │: │:
RGB _N │ Lab _N │ d _N
Where d ₁ <d ₂ <d ₃ <… <d _N

● Step S5
The conversion value (RGB value) for the input Lab value is calculated by the following formula.
RGB = (1 / N) × Σ _{i = 1} ^N RGBi × f (di)
Where f (x) = 1 / (1 + x ⁴ )

  Since the function f (x) has the characteristics shown in FIG. 7, the calculation by the above formula gives a larger weight to the RGB values corresponding to the Lab colorimetric values that are closer in the Lab color space. Interpolation calculation is performed.

  The number N of sample points used for the interpolation calculation may be a constant (for example, 8) in the entire Lab color space. However, depending on the conversion method in the device RGB → CMYK conversion unit 106, as shown in FIG. 5, colorimetric values are concentrated in an area where the lightness L * is low. In other words, the distance d is extremely small in areas where the colorimetric values are concentrated, and if N is small, interpolation is performed with a large weight on a small number of sample points, resulting in a gradation jump in the device RGB color space. , Problems such as white balance collapse in low brightness areas are likely to occur.

  Therefore, as shown in FIG. 8, the above problem can be effectively solved by performing the interpolation calculation by changing the number of sample points according to the L * value of the input Lab value. Of course, even in a high brightness area, the number of samples used for the interpolation calculation is limited, and color turbidity is less likely to occur. Note that an example of the function N (L *) shown in FIG. 8 shows a 1/4 power function that becomes 128 when L * = 0 and 4 when L * = 100.

  If the processes in steps S3 to S5 are repeated for all input Lab values, the Lab signal can be converted into a device RGB signal.

  The image processing apparatus according to the second embodiment of the present invention will be described below. Note that in this embodiment, the same reference numerals as those in the first embodiment denote the same parts, and a detailed description thereof will be omitted.

  FIG. 9 is a block diagram illustrating a configuration example of the image processing apparatus according to the second embodiment. The image processing apparatus according to the second embodiment converts a signal from a device-independent color space signal to a signal in the printer 107 color space, and converts the input signal into a device-independent color space signal. This is different from the image processing apparatus of the first embodiment in that

  The Lab → CMYK conversion unit 803 uses the Lab → CMYK conversion LUT 804 to convert the Lab signal into a CMYK color space signal subordinate to the printer 107. The CMYK signal output from the Lab → CMYK conversion unit 803 is sent to the printer 107. The Lab → CMYK conversion LUT 804 is created as follows.

  The CMYK signal of the sample image generated by the color patch generation unit 808 is output to the printer 107, and the sample image 109 is obtained.

  Each color patch of the obtained sample image 109 is measured by the color patch colorimetric unit 110 to obtain Lab colorimetric values for each color patch. Based on the obtained Lab colorimetric values and the CMYK values generated by the color patch generation unit 808, a CMYK → Lab conversion LUT is created. Then, based on the created CMYK → Lab conversion LUT, a Lab → CMYK conversion LUT 804 is created using the same method as in the first embodiment.

For example, if the Lab value is an 8-bit signal, the L * value is from 0 to 255, and the a * and b * values are from -128 to 127. If the Lab grid is formed by marking each Lab range in 16 steps, a table of Lab → CMYK conversion LUT804 is created by 17 ³ = 4913 calculations.

  In the first embodiment, the Lab color space is converted from the device RGB color space by the LUT, and then converted from the device RGB color space to the CMYK color space by arithmetic processing. In the second embodiment, these conversion processes are performed by one LUT. Can be performed, and the conversion process can be made more efficient.

  The image processing apparatus according to the third embodiment of the present invention will be described below. Note that in this embodiment, the same reference numerals as those in the first embodiment denote the same parts, and a detailed description thereof will be omitted.

  FIG. 10 is a block diagram illustrating a configuration example of the image processing apparatus according to the third embodiment, which has a configuration for inputting an input signal in an sRGB color space, which has recently become a standard color space on the Internet. The sRGB color space has a defined correspondence with the XYZ color space, and can be considered as a color space independent of the device. Therefore, by converting sRGB values to XYZ values and Lab values, and further converting from the Lab color space to the printer color space as described above, the printer 107 reproduces the image represented by the signal in the sRGB color space. It becomes possible to do.

  In FIG. 10, an sRGB → CMYK conversion unit 901 converts an input signal in the sRGB color space into a CMYK color space signal subordinate to the printer 107, using an sRGB → CMYK conversion LUT902. The CMYK signal output from the sRGB → CMYK conversion unit 901 is sent to the printer 107. The sRGB → CMYK conversion LUT 902 is created as follows.

  The RGB signal of the sample image generated by the color patch generation unit 108 is converted into a CMYK signal subordinate to the printer 107 by the device RGB → CMYK conversion unit 106, and then output to the printer 107, whereby a sample image 109 is obtained.

  Each color patch of the obtained sample image 109 is measured by the color patch colorimetric unit 110 to obtain Lab colorimetric values for each color patch. Based on the obtained Lab colorimetric values and the RGB values generated by the color patch generation unit 108, the sRGB → CMYK conversion LUT creation unit 908 creates a table of sRGB → CMYK conversion LUT 902.

The processing of the sRGB → CMYK conversion LUT creation unit 908 is performed on the CMYK value obtained by applying the device RGB → CMYK conversion processing described in the first embodiment to the RGB value generated by the color patch generation unit 108, and the Lab colorimetric value. A table of sRGB → CMYK conversion LUT902 is created from sRGB values obtained by performing Lab → XYZ and XYZ → sRGB conversion according to the definition formula. For example, if an sRGB signal is an 8-bit signal, a sRGB → CMYK conversion LUT902 table is calculated by 17 ³ = 4913 calculations if each sRGB range is carved in 16 steps to form a 17 x 17 x 17 sRGB grid. Is completed.

  According to each of the embodiments described above, it is possible to provide a color conversion method that accurately approximates the strong nonlinear output characteristics of a color printer or printing press and enables highly accurate color reproduction. Therefore, in order to perform color space conversion that well reflects the characteristics of the printer or printing machine in a device-independent color space, high-precision color reproduction can be achieved in the printer or printing machine for any input color space. It becomes possible.

  In the above embodiment, the device-independent color space has been described as the Lab color space. However, the same effect can be obtained by using another uniform color space, for example, the Luv color space.

  In the above embodiment, the method for creating the profile of the output device has been described. The device value (for example, CMYK) → Lab conversion LUT described in the above embodiment corresponds to the destination profile (BtoA0) 1101D of the output device shown in FIG. 12, and the Lab → device value (for example, CMYK) conversion LUT is This corresponds to the source profile (AtoB0) 1101S of the output device shown in FIG.

  For the purpose of proof (test printing, proof printing), an image that has been color-converted according to the output characteristics of the target printing machine may be printed by a copier or printer. In order to perform such proofing, sample image data is supplied to an output device used for proofing and printed by the method described in each of the above-described embodiments, and the colorimetric values of each color patch of the obtained sample image are used. You need to create a profile. Then, an image subjected to color conversion using the created profile is printed by the output device.

  In the following, an embodiment in which a profile of an output device used for proofing is created and a processing result based on the created profile can be confirmed will be described as a fourth embodiment. Needless to say, the profile creation described in the fourth embodiment is not limited to proofing, but can be used for normal output (printing).

[Configuration of color conversion module]
First, an outline of a configuration for performing color conversion using a profile will be described. FIG. 11 is a block diagram illustrating a configuration example of the color conversion module.

  A colorimeter (spectrophotometer) 1001 and a colorimetry module 1002 measure the color of each color patch of a sample image (for example, a standard IT8 or 4320 CMYK image) printed by an output device. The color measurement result is supplied to the profile generation module 1003 online or offline, and the profile 1101D (Lab → CMYK conversion LUT), which is an output device profile, conforms to the definition of ICC (International Color Consortium) by the method described in the above embodiment. : BtoA0) and profile 1101S (device value → Lab conversion LUT: AtoB0) are created.

  The preview module 1005 includes an image 1006 to be proofed, a profile corresponding to the target device (target device value → Lab conversion LUT) 1102, output device profiles 1101D and 1101S, and a monitor profile 1103 to the color management module (CMM) 1007. Supply (or instruct) to cause image 1006 to undergo color conversion.

  The creation of the profile in the fourth embodiment uses the same method as in the above-described embodiment. In the following, functions in the fourth embodiment for improving user convenience will be described in detail.

[Color measurement processing]
The color conversion module shown in FIG. 11 is implemented by being supplied as software to a personal computer, for example. Then, the user interface displayed on the monitor 1004 can instruct execution of the color measurement process.

  FIG. 14 is a flowchart showing the color measurement procedure, which is executed by the profile generation module 1003 shown in FIG. This color measurement process corresponds to the process of the color patch color measurement unit 110 shown in FIG.

  When the operator instructs the start of color measurement, a window shown in FIG. 15 is displayed in step S21. The operator displays the colorimeter, colorimetric parameters (colorimetric light source, colorimetric field of view and color space) and sample image ( Select the color chart type from the pop-up menu.

  When the [OK] button in the window shown in FIG. 15 is pressed, in step S22, a window shown in FIG. 16 is displayed, and the operator sets the sample image output by the output device on the colorimetry table according to the instruction.

  When the [OK] button in the window shown in FIG. 16 is pressed, a window shown in FIG. 17 is displayed in step S23, and the operator sets the upper left of the colorimetric range of the sample image according to the instruction. Subsequently, windows shown in FIG. 18 and FIG. 19 are displayed, and the operator sets the upper right and lower right of the colorimetric range of the sample image according to the instruction.

  When the above operation is completed, each color patch of the sample image is measured by the colorimeter 1001 and the color measurement module 1002 in step S24. When the color measurement is completed, it is determined in step S25 whether or not the color measurement of all the sample images has been completed. If the color measurement has not been completed, the process returns to step S22, and the processes of steps S22 to S24 are repeated. If the sample image is A4 size, two colorimetric measurements are required for the IT8 image (928 patch) and 10 for the 4320CMYK image (4320 patch).

  When the color measurement of the sample image is completed, the color measurement result is displayed in color in step S26. FIG. 20 is a diagram illustrating an example of a window in which the color measurement result is displayed. Each small frame of the color measurement result in FIG. 20 represents each color patch and is displayed in the color measured. The ● mark in the small frame indicates a warning (details will be described later) for the color measurement result.

  The operator refers to the color measurement result displayed in FIG. 20 and determines whether or not to perform color measurement again in step S27. If re-color measurement is instructed, only the color patch with the warning mark (●) is re-measured in step S28, and then the process returns to step S26, and the color measurement result is displayed again.

  In this way, the profile generation module 1003 creates a profile of the output device based on the Lab colorimetric values measured from the sample image in the same manner as in the above embodiment. According to the fourth embodiment, the operator can easily set complicated parameters by the above-described user interface, and can accurately measure the color of the sample image.

  In the above description, the color measurement result is displayed after the reading of the sample image is completed. However, the color measurement result can be displayed every time reading of each color patch is completed.

[Warning]
Hereinafter, the warning-related processing performed in step S26 will be described in detail.

  FIG. 21 is a diagram showing a table example in which standard colorimetric values used in the color patch generation unit 108 are stored. When outputting a sample image (color patch 109), the CMYK values stored in the table are output to the output device, and the output device outputs the sample image.

  In FIG. 21, standard Lab colorimetric values and tolerance ΔE are defined for the CMYK values of each color patch. This table is prepared in advance according to the type of sample image (color chart) that can be selected in the user interface shown in FIG. However, since this table is in a text format with blanks and commas as delimiters, the Lab colorimetric values and tolerance ΔE can be set arbitrarily.

If the profile generation module 1003, a colorimetric values Lab of the color patches, corresponding by comparing the standard values Lab _i stored in the table, the difference exceeds the allowable difference Delta] E, a warning mark on the colorimetric result Add.
if (| Lab-Lab _i |> ΔE) Warning mark _i = true;

  Therefore, when the color measurement result of a color patch deviates from a standard color measurement value by a tolerance or more, a warning mark is displayed on the color measurement result of the color patch. When the operator instructs re-measurement, only the color patch with a warning mark attached to the color measurement result is re-measured, and the color measurement result is displayed again.

  As described above, the fourth embodiment has a function of performing colorimetry only on the color patch on which the warning mark is displayed. This function eliminates the need to measure all color patches when performing colorimetry again. In addition, it is not necessary for the user to manually specify a color patch to be re-measured. Therefore, the minimum necessary re-measurement can be easily performed.

  Thus, by displaying the warning mark, the state of the output device can be grasped. For example, when a large number of warning marks are displayed or when warning marks are concentrated on a color patch of a certain color, the color reproduction characteristics of the output device will be significantly different from the standard. Even if the profile is optimized, it can be judged that it is difficult to realize a highly accurate proof.

  Furthermore, since the tolerance ΔE can be set in the fourth embodiment, for example, the warning mark can be made a judgment material suitable for the user's application by controlling the tolerance ΔE according to the user's application. it can. Also, since the tolerance ΔE can be set for each color patch, the warning mark is suitable for the user's application by making the tolerance ΔE of colors important to the user (for example, skin color) more strict than other colors. Can be used as a judgment material.

  When a plurality of tables shown in FIG. 21 are prepared and a color patch is output to the output device, the table is selected by the user according to the user's application and the type of output device. By so doing, it is possible to perform the warning display according to the user's application and the type of output device. The selection from the plurality of tables may be made possible by using the pop-up menu “type of color chart” shown in FIG. 15 in step S21 shown in FIG. The names of the tables displayed in the pop-up menu may be displayed so that the user can arbitrarily add titles and comments to each table.

  Also, if most of the color patches are marked with a warning mark, it may be due to a lack of colorimetry. Therefore, it is necessary to reset the color measurement conditions and perform color measurement again.

[Create profile]
Next, creation of an output device profile will be described in detail.

  FIG. 22 is a diagram for explaining a procedure for creating a target profile, and is a diagram for more simply explaining the processing described in the second embodiment.

  The device CMYK data of the sample image selected by the user from the memory 1012 is supplied to the output device 1010, and the sample image 1011 is printed. For example, a standard IT8 or 4320CMYK image is used as the sample image.

  Each color patch of the sample image 1011 printed by the output device 1010 is measured by the colorimeter 1001 and the color measurement module 1002, and the Lab colorimetric value is stored in the memory 1012. The profile generation module 1003 generates a device CMYK → Lab conversion table 1013 corresponding to the AtoB0 tag of the ICC profile and stores it in the memory 1012.

  Considering the preview function described later, since the BtoA0 tag is required in addition to the AtoB0 tag, the profile generation module 1003 creates the Lab → device CMYK conversion table 1014 from the device CMYK → Lab conversion table 1013. These conversion tables are finally stored in the memory 1012 as the ICC profile of the output device 1010.

  By the way, the device CMYK values in the device CMYK → Lab conversion table 1013 are evenly arranged, but the Lab colorimetric values are not evenly arranged. When creating the Lab → device CMYK conversion table 1014 with Lab values as input, it is necessary to arrange Lab values evenly. Therefore, using the method described in the first embodiment, an Lab → device CMYK conversion table 1014 in which Lab values are evenly arranged is created from the device CMYK → Lab conversion table 1013 and stored in the memory 1012.

[Smoothing of colorimetric values]
Since the colorimeter 1001 is calibrated before use, the accuracy of colorimetry is ensured. However, it is unavoidable that there is some color measurement error. There may also be a color patch of the sample image 1011 that could not be formed satisfactorily depending on the state of the output device 1010. Therefore, if necessary, smoothing is performed on the Lab colorimetric values in order to suppress the influence of measurement errors and color patches that cannot be formed satisfactorily.

  FIG. 23 is a flowchart showing a procedure for smoothing colorimetric values.

  In step S11, Lab colorimetric values located on each side of the CMYRGBWK hexahedron in the Lab color space, which are configured by Lab colorimetric values of the sample image 1011 output by the output device 1010 shown in FIG. 22, are smoothed. . As a smoothing method, a predetermined number of sampled colorimetric values and Lab colorimetric values on the same side in the vicinity thereof are sampled, and an average or weighted average thereof is used as a Lab colorimetric value of the target colorimetric value.

  Next, in step S12, the Lab colorimetric values on each surface of the hexahedron are smoothed using the Lab colorimetric values smoothed in step S11 and the Lab colorimetric values located on each surface. Subsequently, in Step S13, Lab colorimetric values inside the hexahedron are smoothed using Lab colorimetric values located on each side and each surface of the hexahedron smoothed in Steps S11 and S12.

  Then, the device CMYK → Lab conversion table and the Lab → device CMYK conversion table are created by the above method using the smoothed Lab colorimetric values.

  The device RGB value (108 in FIG. 1) used to output the color patch also forms a solid in the RGB color space. The sides and faces of the hexahedron in the Lab color space correspond to the sides and faces of the solid in the RGB color space, respectively. Therefore, which value of the Lab colorimetric value is located on the side or surface can be easily selected from the device RGB values of the color patch used to output the sample image 1011.

  Note that the colorimetric Lab values may be plotted in the Lab color space, and the results may be analyzed to select Lab colorimetric values located on the sides and the surfaces.

  The smoothing of the colorimetric values has the following advantages and disadvantages. As an advantage, it is possible to suppress the color measurement error and the influence of the color patch that cannot be formed satisfactorily. On the other hand, as a disadvantage, when the colorimetry and the formation of the color patch are performed well, the accuracy of the measurement result is lowered.

[Smoothing conversion table]
Printers and printing presses have strong nonlinear output characteristics. Therefore, if a profile created based on the color measurement result is used, a pseudo contour or the like is likely to occur in the output image. Therefore, if necessary, smoothing is applied to the conversion table in order to maintain gradation continuity.

  In the case of the device CMYK → Lab conversion table 1013, a predetermined number of Lab values corresponding to the target lattice point (CMYK input value) and Lab values of neighboring lattice points are sampled, and a weighted average of the Lab values corresponding to the target lattice point is obtained. Value (output value).

  Similarly, the smoothing of Lab → device CMYK conversion table 1014 samples a predetermined number of CMYK values corresponding to the target grid point (Lab input value) and CMYK values of neighboring grid points, and sets the weighted average as the target grid point. Set to the corresponding CMYK value (output value).

  As a weighting method, the weight of the output value corresponding to the target lattice point (input value) is made smaller than the total weight of the output values of neighboring lattice points. For example, assuming that the sampling number is 7, the weight corresponding to the target lattice point is 0.4, and the weight corresponding to six neighboring lattice points is 0.6 / 6. Note that the weighting method is changed based on the number of grid points of the conversion table to be created set by the “optimization” pop-up menu of the user interface shown in FIG. For example, when the number of grid points is small and the grid point interval is wide, the weights corresponding to neighboring grid points are reduced.

  The smoothing of the conversion table has the following advantages and disadvantages. As an advantage, the continuity of gradation can be improved and the pseudo contour of the output image can be suppressed. On the other hand, the disadvantage is that the fidelity to the color reproduction characteristics of the printer is lowered.

[Interface]
The color conversion module shown in FIG. 11 is implemented by being supplied as software to a personal computer, for example. Whether or not to perform the above smoothing can be set by a user interface displayed on the monitor 1004.

  24 and 25 are diagrams illustrating an example of a parameter setting screen displayed when creating a profile of the output device 1010. FIG.

  When the “Smooth colorimetric values” check box on the screen of FIG. 24 is checked, the above colorimetric value smoothing is executed.

  If the “Smooth” check box on the source side of the screen in FIG. 25 is checked, the device CMYK → Lab conversion table 1013 is smoothed, and if the “Smooth” check box on the destination side is checked, Lab → device CMYK conversion Table 1014 is smoothed.

  As described above, in this embodiment, smoothing for the conversion table can be set independently for the device value → Lab conversion table 1013 and the Lab → device value conversion table 1014. On the other hand, the colorimetric value smoothing cannot be set independently. This is based on the difference in the purpose of each smoothing, that is, the colorimetric value smoothing is a process corresponding to the colorimetric accuracy, and the conversion table smoothing is a process corresponding to the conversion process result of each conversion table. is there.

  Further, the number of grids of the device CMYK → Lab conversion table 1013 and the Lab → device CMYK conversion table 1014 can be set by the “optimization” pop-up menu on the source side and the destination side shown in FIG. That is, “precision priority” or “speed priority” can be selected as an optimization from the pop-up menu.

  When “accuracy priority” is selected, the device CMYK → Lab conversion table 1013 has a 17 × 17 × 17 × 17 lattice, and the Lab → device CMYK conversion table 1014 has a 33 × 33 × 33 lattice. If “speed priority” is selected, the device CMYK → Lab conversion table 1013 has a 9 × 9 × 9 × 9 lattice, and the Lab → device CMYK conversion table 1014 has a 17 × 17 × 17 lattice.

  Thus, the fact that the number of grid points can be set independently for each conversion table is one reason why smoothing can be set independently for each conversion table.

  Further, the warning process for the colorimetric value described above can be used as a material for determining whether or not to smooth the colorimetric value. For example, when warning marks are displayed on a large number of color patches, it may be better to smooth the colorimetric values.

[history management]
The target profile created from the colorimetric results according to the above procedure is saved in the memory 1012, but at that time, the profile creation history etc. can be saved to manage how the profile was created. .

  FIG. 26 is a flowchart showing an example of a procedure for storing a profile, colorimetric values, and history management information, which is executed by the profile generation module 1003.

  When profile generation by the profile generation module 1003 is completed, a window shown in FIG. 27 is displayed on the monitor 1004 in step S31, and the operator saves the parameters related to file storage (storage location and profile name) and colorimetric values. Whether to store history management information or not. By default, the extension of the profile name is “icc”. The colorimetric value file name and the history management information file name are obtained by changing only the extension of the profile name to “it8” or “pbh”.

  Next, in step S32, it is determined whether or not the history management information is to be saved. If not, the process jumps to step S36.

  When saving history management information, the window shown in Fig. 28 is displayed in step S33, and the operator displays the status at the time of sample image output (output date, output person, printer name and installation location, and usage) Paper and ink) and the status (storage location) when the sample image is stored.

  Subsequently, in step S34, a window shown as an example in FIG. 29 is displayed, and the operator sets the color measurement status (color measurement date, colorimeter, colorimeter, colorimetric light source, and colorimetric field of view) and the like. .

  Subsequently, in step S35, a window shown in FIG. 30 is displayed, and the operator sets the situation (operator and remarks) at the time of creating the w profile. At the time of profile creation, “Presence / absence of white point correction of colorimetric value”, “Presence / absence of smoothing of colorimetric value”, “Optimization (priority priority or speed priority)”, “Presence of smoothing”, “Table accuracy ( Parameters such as “8 bit or 16 bit)” bit precision are set, but those parameters are automatically saved in the history management information.

  Next, in step S36, the set parameter list is displayed on the monitor 1004. If the operator wishes to correct / modify parameters, the process returns to step S31. If correction / correction is not necessary, the process proceeds to step S37, and a profile with a file name ddcp.icc, for example, is stored in a specified storage location, for example, a specified directory or folder in the memory 1012.

  Next, in step S38, it is determined whether or not the colorimetric values are to be saved. If so, in step S39, a list of the colorimetric values in the text file format of the file name ddcp.it8, for example, in the same storage location as the profile. (See FIG. 31) is saved.

  Next, in step S40, it is determined whether or not the history management information is to be saved. If so, in step S41, the history management information in a text file format (for example, a file name ddcp.pbh) is stored in the same storage location as the profile (FIG. 32) is saved.

  In this manner, not only the created target profile but also the colorimetric results used for creating the profile, the colorimetric information, and the history information at the time of creating the profile can be stored and managed. Therefore, when there is an abnormality in the created profile, it is easy to deal with problems such as searching for the cause by referring to history information or recreating the profile from the stored colorimetric results. .

[preview]
A preview function for performing monitor display for confirming whether the created target profile is appropriate will be described. The preview function is activated after the profile is created by the above processing.

  FIG. 12 is a diagram showing a color conversion procedure executed by the CMM 1007 shown in FIG.

  The CMYK data of the image 1006 is converted to Lab data by the AtoB0 tag of the target device profile 1102, and converted to CMYK data of the CMYK color space subordinate to the output device 1010 by the BtoA0 tag (destination profile 1101D) of the output device profile 1101. The When proofing is performed, the CMYK data is sent to an output device for proofing.

  The CMYK data in the CMYK color space depending on the target is converted back to Lab data by the AtoB0 tag (source profile 1101S) of the output device profile 1101. The Lab data is converted into RGB data in a color space subordinate to the monitor 1004 by the monitor profile 1103 and displayed on the monitor 1004. That is, an image that will be printed by the target, that is, a preview image B can be displayed on the monitor 1004, and its color reproducibility can be observed.

  Furthermore, if the Lab data converted by the target device profile 1102 is directly converted to RGB data by the monitor profile 1103 and displayed as the original image A on the monitor 1004, a preview image that has undergone color conversion by the output device profile 1101 is displayed. B and the original image A that has not been received (the image that the target device will output) can be observed and compared on the monitor 1004. Accordingly, whether or not the created output device profile 1101 is appropriate can be confirmed by observing and comparing both images.

  FIG. 13 shows an example of a preview screen displayed on the monitor 1004. For example, the original image A is displayed on the left side and the preview image B is displayed on the right side. Although FIG. 13 shows an example in which the window sizes of both images are the same, an arbitrary window size can be obtained by moving the centers of both windows with a mouse or the like.

  When the magnification setting at the upper left of the preview screen is changed, the magnification changes for both images. In addition, when one image is scrolled, the other image is also scrolled together, that is, the upper left position of the screen is always at the same position on the image. Further, when the mouse cursor is placed on one image and the mouse button is pressed, for example, the mouse cursor is displayed at a corresponding position on the other image. Such a preview screen user interface makes it easy to observe and compare details of both images in detail.

  According to the fourth embodiment, the creation result of the output device profile 1101 can be easily confirmed. In addition, since the preview image (display image A) of the target device suitable for the proof use and the image (display image B) processed using the created output device profile 1101 are displayed side by side, the output device Confirmation of the creation result of the profile 1101 is extremely easy.

  A method for predicting the image processing and device profile re-creation time according to the fifth embodiment of the present invention will be described below. Note that the same reference numerals in the present embodiment denote the same components as in the first to fourth embodiments, and a detailed description thereof will be omitted.

  [Prediction of profile rebuild time]

  FIG. 33 is a diagram showing the concept of profile recreation time.

Reads the colorimetric values Lab and its history information for the color patches output at different times, compares the measured color value, a standard colorimetric values Lab _i shown in Example 4. Here, when the standard colorimetric value Lab _i does not exist, the colorimetric value used to create the profile is substituted for the standard colorimetric value Lab _i .

From the relationship between the “color chart output date” of the history information and the color chart average color difference with respect to the standard colorimetric value Lab _i , the color difference variation is obtained in time series. Here, the color difference fluctuations arranged in time series need not have a constant interval, in other words, the intervals of “color chart output dates” may be uneven. The timing at which the curve approximated to connect the color difference values at each “color chart output date” intersects the color difference tolerance level dEi is obtained, and this timing is set as the profile recreation time.

For the sake of simplification, a straight line approximation is used to obtain a period Tm from when a profile is created until the profile is created again.
Tm = T1 + (T2-T1) (dEi-dE1) / (dE2-dE1)
Where dEi: acceptable color difference
dE2: Color difference exceeding the allowable level
T2: Tolerance level exceeded from the date of profile creation
Period until “Color Chart Output Date”
dE1: Color difference just before the allowable level is exceeded
T1: Immediately before exceeding the allowable level from the date of profile creation
Period until “Color Chart Output Date”

  Accordingly, when the color difference exceeds the allowable level dEi, the profile is recreated, and Tm may be set as the profile recreation period. Although Tm is calculated every time a profile is re-created, it is desirable to optimize Tm in consideration of Tm calculated in the past. The next rebuilding time can be obtained based on the rebuilding period Tm calculated in the past. For example, it is possible to obtain an optimized rebuilding time by taking the average of the past rebuilding periods Tm calculated in the past (before the previous time).

  FIG. 34 is a flowchart showing an example of processing for predicting and warning the profile re-creation time.

  Whether or not the profile re-creation time is approaching is determined by whether or not the difference between the elapsed time from the previous profile creation date and Tm has reached a predetermined value (for example, 14 days) (S101), and the profile re-creation When the time approaches, for example, data for displaying a warning as shown in FIG. 35 is generated and output to a monitor or the like (S102). It is also possible for the user to freely set the time for displaying the warning (14 days before in the example of FIG. 34).

  Next, it is determined whether or not the profile has been re-created (S103), and if re-created, the memory 1012 and the like are stored in accordance with the parameters related to file storage (save location and profile name, see FIG. 27) specified by the user. History management information (colorimetry history) is read, and the above-described profile re-creation period Tm is predicted (S104). Thereafter, the process returns to step S101.

[Color difference display]
In addition to the warning display shown in FIG. 35, it is also possible to allow the user to decide when to recreate the profile by generating data that visually shows the color difference variation as shown in FIG. 36 and outputting it to a monitor etc. It is. The display of the color difference variation shown in Fig. 35 shows the average color difference for the entire color patch (the entire device color space), the average color difference for a partial color space area such as the skin color area, and the color difference for a custom color such as a spot color. This is an example.

  It is also possible to set different color difference tolerance levels dEi for each color difference variation. Then, even if the average color difference for the entire color patch does not exceed the allowable level, for example, a warning can be issued when the color difference for the skin color region exceeds the allowable level.

  The management of the project database (hereinafter referred to as “project DB”) and the colorimetric value database (hereinafter referred to as “colorimetric value DB”) according to the sixth embodiment of the present invention will be described below. Note that the same reference numerals in the present embodiment denote the same components as in the first to fourth embodiments, and a detailed description thereof will be omitted.

[Management of Project DB and Colorimetric Value DB]
FIG. 37 is a conceptual diagram showing a method for managing the project DB and the colorimetric value DB.

  The project DB in which information necessary for profile creation is collected and the colorimetry value DB in which colorimetric data used for profile creation are collected exist on the server 1501, and the created profile is received from the client 1502. Present on 1504.

  The profile generation module 1003 of each client analyzes the created profile and acquires necessary information from each DB. When a new profile is created, the profile generation module 1003 registers history management information and colorimetric value data in each database. Here, the project DB and the colorimetric value DB do not need to exist on the same server 1501 as long as they can be referred to each other, and may be distributed to two servers. The database may be ODB (Object oriented Data Base), RDB (Relational Data Base), or a general data file.

  Also, as shown in FIG. 38, information such as profile version and profile build number is stored in the private tag of each profile so that the database can be searched. The profile version is a number for managing the release version. The profile build number indicates the number of times the build is performed to release the profile, and is automatically incremented by the profile generation module 1003.

  When the profile generation module 1003 is activated on each client, a login screen shown in FIG. 39 as an example for connecting to the database is displayed on the client monitor. If the login name and password entered on the login surface by the client user are correct, the profile generation module 1003 running on the client is connected to the project DB and the colorimetric value DB. The case where the database is RDB will be described below.

  As shown in FIG. 40, the project DB stores user names, profile information, colorimetric value IDs, profile generation parameters, and the like as a project table.

  In the color measurement value DB, as shown in FIG. 41, a color measurement value ID, color measurement information, actual color measurement value data, and the like are stored as a measurement table. If the colorimetric value data for the same color device is used, it is possible to create new colorimetric value data by simple average or weighted average using colorimetric value data with different colorimetric dates and times. For example, colorimetric value data with colorimetric value ID = 3 can be created by simply averaging the colorimetric value data with colorimetric value ID = 1 and 2.

[Use Project DB]
When the profile generation module 1003 reads the profile, it collects information from the read profile. Then, for example, the following inquiry is made to the project DB.
SELECT COUNT (*) FROM ProjectTable
WHERE User = 'Taro' AND ManufacturerID = 'CANO' AND
Attribute = '00000000' AND CreatorID = 'CANO' AND
ProfileVersion = 1 AND BuildNumber = 1

  In the above query, “User” is the user name, “ManufacturerID” is the manufacturer ID, “Attribute” is the attribute, “CreatorID” is the creator ID, “ProfileVersion” is the profile version, and “BuildNumber” is the profile. Each field of the number of builds is indicated, and a value indicating whether records satisfying the conditions of those fields are stored is returned to the COUNT from the project DB.

  [Automatic resetting of profile generation parameters and acquisition of colorimetric data]

  If “0” is returned from the project DB in response to the inquiry, it indicates that the profile has no history in the project DB. Therefore, the profile generation module 1003 displays a message such as “Not registered in database” on the monitor.

  When “1” is returned from the project DB in response to the inquiry, this indicates that the profile has a history in the project DB, and the profile generation module 1003 uses the profile generation parameter as an initial value when generating a profile. The setting parameters can be reproduced. Therefore, the user can know what profile generation parameter the read profile is created with.

  An error is indicated when “2” or more is returned from the project DB in response to the inquiry.

If the user wants to know the profile generation parameters, or if he wants to fine-tune the profile generation parameters and create the profile again, the profile generation module 1003 obtains the color measurement value data from the color measurement value DB by the following query, for example To do.
SELECT colorimetric data FROM ProjectTable, MeasurementTable
WHERE User = 'Taro' AND ManufacturerID = 'CANO' AND
Attribute = '00000000' AND CreatorID = 'CANO' AND
ProfileVersion = 1 AND BuildNumber = 1 AND
ProjectTable. Colorimetric ID = MeasurementTable. Colorimetric ID

  When a profile is recreated, the profile is registered in the project DB as a new profile.

[Create new profile and automatically assign number of profile builds]
When a profile is newly created, the profile generation module 1003 makes the following inquiry to the project DB, for example.
SELECT COUNT (*) FROM ProjectTable
WHERE User = 'Taro' AND ManufacturerID = 'CANO' AND
Attribute = '00000000' AND CreatorID = 'CANO' AND
ProfileVersion = 1

  In response to this inquiry, the number of profile builds corresponding to the specified device and profile version is returned from the project DB to COUNT, so the profile generation module 1003 sets the profile build number to the generated profile. At the same time, the profile generation module 1003 registers profile information, colorimetric value IDs, and profile generation parameters in the project DB.

  The colorimetric value ID registered in the project DB uses the colorimetric value ID obtained by registering in the colorimetric value DB when new colorimetric value data is used. When colorimetric value data is used, the corresponding colorimetric value ID is used.

[History function]
In this embodiment, since all past profile creation histories are registered in the database, not only the previous profile creation environment can be reproduced, but also all past profile creation environments can be reproduced. For example, the number of past creations for a specific profile can be inquired by the following inquiry.
SELECT COUNT (*) FROM ProjectTable
WHERE User = 'Taro' AND ManufacturerID = 'CANO' AND
Attribute = '00000000' AND CreatorID = 'CANO'

  If each database includes time stamp information, the profile generation module 1003 can also display a list of time-stamped profile creation histories on the monitor. The user can refer to this list, select a past profile creation history, and reproduce settings of profile creation parameters used in the past. In addition, by including time stamp information, it is possible to predict the profile recreation time in consideration of changes in the environment such as the climate at the time the profile was created.

  As described above, in this embodiment, since the profile creation history and colorimetric value data of each user are centrally managed by the database, a statistical method such as predicting the timing for re-creating the profile from the information registered in the database is used. Processing can also be performed easily.

  When the profile generation module 1003 operates on a stand-alone PC, the project DB and the colorimetric value DB can be realized as a general data file without using the RDB or ODB.

[Other embodiments]
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.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. 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. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after 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, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

Claims (8)

An acquisition means for acquiring a colorimetric value obtained by measuring a color chart output by an output device based on a colorimetric condition;
Creating means for creating a profile of the output device based on a profile creation condition using the acquired colorimetric value;
Profile storage means for storing the created profile;
A color processing apparatus comprising: a colorimetric light source and a colorimetric visual field that are the colorimetric conditions; and a condition storage unit that stores the creation conditions independently of the profile.   2. The color processing apparatus according to claim 1, further comprising colorimetric value storage means for storing the acquired colorimetric values.   3. The profile, the colorimetric condition, the creation condition, and the colorimetric value are stored in the same storage location as a data file having the same file name with a different extension. Color processing device.   The condition storage means further stores paper and printer names used for the output of the color chart, and an output date of the color chart as information indicating a situation at the time of output of the color chart. 4. The color processing apparatus according to claim 1, wherein:   The apparatus further comprises instruction means for enabling manual indication as to whether or not to store each of the colorimetric conditions, information indicating the status at the time of output, and the colorimetric values. The color processing apparatus described in 4.   The profile includes a table that converts device values of the output device into color values in a color space independent of the device, and a table that converts color values in a color space independent of the device into the device values. 6. The color processing apparatus according to claim 1, wherein: A color processing method of a color processing apparatus having an acquisition means, a creation means, a profile storage means and a condition storage means,
The obtaining means obtains a colorimetric value obtained by measuring the color chart output by the output device based on the colorimetric condition;
The creation unit creates a profile of the output device based on a profile creation condition using the acquired colorimetric value,
The profile storage means stores the created profile,
A color processing method, wherein the condition storage means stores a colorimetric light source and a colorimetric visual field, which are the colorimetric conditions, and the creation conditions independently of the profile.   A program causing a computer device to function as each unit of the color processing device according to any one of claims 1 to 6.

Images