JP2003283856A5 - - Google Patents

Description

[Document name] statement
[Description of the invention] A color conversion table creating method, a color conversion table creating apparatus, a color conversion table creating program, and a medium storing the color conversion table creating program
[Claim of claim]
    1. Correspondence between a first color image data composed of a plurality of element colors and a second color image data composed of a plurality of different element colors that can be used by an imaging device that outputs an image with respect to a plurality of reference points A color conversion table creating method for creating a color conversion table to be defined, comprising:
  An intermediate correspondence determination step of determining an intermediate correspondence between the intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and the second color image data;
  Based on the above determined intermediate correspondenceMultipleColor conversion for converting the number of intermediate color image data into the second color image data, outputting a plurality of corresponding images to the image device, and measuring the plurality of output images to obtain a color measurement result Result acquisition process,
  And a table creating step of creating the color conversion table by determining the correspondence between the first color image data and the second color image data based on the intermediate correspondence and the colorimetric result. How to make a color conversion table.
    2. A use area determining step of determining a use area of the second color image data to be used by the image device based on the color measurement result is provided,
  2. The color conversion according to claim 1, wherein in the table creating step, the color conversion table is created by determining the correspondence between the first color image data and the use area of the second color image data. Table creation method.
    3. The color conversion table creation method according to claim 2, wherein the color measurement result is each component value of a device independent color space.
    4. In the area-of-use determination step, the gradation value of all the element colors in the second color image data is on the low gradation side, and the graininess of the same element color of the image output from the image device A second embodiment of the present invention is to determine the use area of the second color image data except for a predetermined granular appearance area where the image is prominent.To 3Described color conversion table creation method.
    5. The intermediate correspondence determination step according to claim 1, wherein data within a range which can be output by the image device among the second color image data is associated with the intermediate color image data. The color conversion table creation method according to any one of claims 4 to 10.
    6. In the intermediate correspondence determination step, the intermediate color image data and the second color image data are in a one-to-one relationship, and the colorimetry result acquired in the colorimetry result acquiring step 6. The color conversion table creation method according to claim 1, wherein the intermediate correspondence relationship is determined such that “1” and “1” have a one-to-one relationship with the intermediate color image data.
    7. In the table creating step, the correspondence between the first color image data and the intermediate color image data is determined based on the color measurement result, and based on the correspondence and the intermediate correspondence. The color conversion table creation method according to any one of claims 1 to 6, wherein the color conversion table is created by determining the correspondence between the first color image data and the second color image data. .
    8. The color measurement result is each component value of a device-independent color space,
  An input-side correspondence determining step of determining an input-side correspondence between the first color image data and each component value of the device-independent color space;
  In the table creating step, the color conversion table is determined by determining the correspondence between the first color image data and the second color image data based on the input side correspondence, the color measurement result, and the intermediate correspondence. The color conversion table creation method according to any one of claims 1 to 7, wherein the method is created.
    9. The element color of the second color image data is composed of four or more colors, and the intermediate element color is composed of three colors. Described color conversion table creation method.
    10. A color that defines, for a plurality of reference points, a correspondence between a first color image data of a plurality of element colors and a second color image data of 4 or more different element colors usable by the printer. A color conversion table creating method for creating a conversion table, comprising:
  Interim correspondence between intermediate color image data consisting of three intermediate color colors and data within the printable range of the second color image data is determined to be one to one. Intermediate correspondence determination process,
  A plurality of intermediate color image data provided with a plurality of density steps for each of the intermediate element colors is color converted to the second color image data based on the determined intermediate correspondence, and a plurality of corresponding patches are printed on the printer A colorimetry result acquiring step of acquiring a colorimetry result based on a device-independent color space by measuring a plurality of printed patches by using a colorimeter;
  A use area determining step of determining a use area of the second color image data to be used by the printer based on the color measurement result;
  The correspondence between the first color image data and the intermediate color image data is determined based on the color measurement result, and the first color image data and the second color image are determined based on the correspondence and the intermediate correspondence. And a table creating step of creating a color conversion table by determining a correspondence relationship with data.
    11. A second intermediate correspondence determining step of determining a second intermediate correspondence between the second intermediate color image data consisting of a smaller number of second intermediate element colors than the intermediate element colors and the intermediate color image data. Is provided,
  In the table creating step, the correspondence between the first color image data and the second color image data is determined based on the intermediate correspondence, the second intermediate correspondence, and the color measurement result, and the color conversion table is determined. The color conversion table creation method according to any one of claims 1 to 8, wherein
    12. A colorimetric result correspondence relationship between the second intermediate color image data and the same colorimetric result is obtained based on the colorimetric result and the second intermediate correspondence relationship, and based on the colorimetric result correspondence relationship. A use area determination step of determining the use area of the second color image data used by the image device;
  In the table creating step, the color conversion table is created by determining the correspondence between the first color image data and the use area of the second color image data based on the correspondence relationship between the color measurement results. The color conversion table creation method according to claim 11.
    13. A color that defines, for a plurality of reference points, a correspondence between a first color image data of a plurality of element colors and a second color image data of 5 or more different element colors usable by the printer. A color conversion table creating method for creating a conversion table, comprising:
  Interim correspondence between intermediate color image data consisting of four intermediate color colors and data within the printable range of the second color image data is determined to be a one-to-one relationship. Intermediate correspondence determination process,
  A plurality of intermediate color image data provided with a plurality of density steps for each of the intermediate element colors is color converted to the second color image data based on the determined intermediate correspondence, and a plurality of corresponding patches are printed on the printer A colorimetry result acquiring step of acquiring a colorimetry result based on a device-independent color space by measuring a plurality of printed patches by using a colorimeter;
  A second intermediate correspondence determining step of determining a second intermediate correspondence between the second intermediate color image data consisting of the three second intermediate element colors and the intermediate color image data to have a one-to-one relation; ,
  Based on the acquired colorimetric result and the determined second intermediate correspondence relationship, the colorimetric result correspondence relationship between the second intermediate color image data and the same colorimetric result is determined, and the colorimetric result correspondence relationship is obtained. A use area determining step of determining a use area of the second color image data to be used by the printer based on the use area;
  The correspondence between the first color image data and the second intermediate color image data is determined based on the correspondence between the color measurement results, and based on the correspondence, the second intermediate correspondence, and the intermediate correspondence. A method for creating a color conversion table, comprising: a table creating step of creating the color conversion table by determining the correspondence between the first color image data and the use area of the second color image data.
    14. A plurality of reference points corresponding to a first color image data of a plurality of element colors and a second color image data of a plurality of different element colors usable in an image device for outputting an image A color conversion table creating method for creating a color conversion table to be defined, comprising:
MultipleA colorimetry result acquiring step of outputting a plurality of corresponding images to the image device based on the number of second color image data, and measuring the plurality of output images to acquire a colorimetry result;
  An intermediate correspondence determination step of determining an intermediate correspondence between the intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and the second color image data;
  The colorimetric result correspondence relationship between the intermediate color image data and the colorimetric result is determined based on the acquired colorimetric result and the determined intermediate correspondence relationship, and the image is determined based on the colorimetric result correspondence relationship. A use area determining step of determining a use area of the second color image data used by the device;
  A table creating step of creating the color conversion table by determining the correspondence between the first color image data and the use area of the second color image data based on the intermediate correspondence and the colorimetric result correspondence; A method of creating a color conversion table, comprising:
    15. A color that defines, for a plurality of reference points, a correspondence between a first color image data consisting of a plurality of element colors and a second color image data consisting of four or more other element colors usable by the printer A color conversion table creating method for creating a conversion table, comprising:
  Based on a plurality of second color image data provided with a plurality of density steps for each of the other element colors, a corresponding plurality of patches are printed by the printer, and the printed plurality of patches are measured by a colorimeter. Color measurement result acquiring step of acquiring a color measurement result based on a device-independent color space;
  Interim correspondence between intermediate color image data consisting of three intermediate color colors and data within the printable range of the second color image data is determined to be one to one. Intermediate correspondence determination process,
  The colorimetric result correspondence relationship between the intermediate color image data and the colorimetric result is determined based on the acquired colorimetric result and the determined intermediate correspondence relationship, and the printer is determined based on the colorimetric result correspondence relationship. A use area determining step of determining a use area of the second color image data to be used by
  The correspondence between the first color image data and the intermediate color image data is determined based on the correspondence between the colorimetric results, and the first color image data and the first color image data are determined based on the correspondence and the intermediate correspondence. And a table creating step of creating the color conversion table by determining the correspondence between the two color image data and the use area.
    16. A plurality of reference points corresponding to a first color image data of a plurality of element colors and a second color image data of a plurality of different element colors usable in an imaging device for outputting an image A color conversion table creating apparatus for creating a color conversion table to be defined, comprising:
  Intermediate correspondence determination means for determining an intermediate correspondence between the intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and the second color image data;
  Based on the above determined intermediate correspondenceMultipleColor conversion for converting the number of intermediate color image data into the second color image data, outputting a plurality of corresponding images to the image device, and measuring the plurality of output images to obtain a color measurement result A result acquisition means,
  And a table creation unit configured to determine the correspondence between the first color image data and the second color image data based on the intermediate correspondence and the colorimetric result, and to create the color conversion table. Color conversion table creation device.
    17. A plurality of reference points corresponding to a first color image data of a plurality of element colors and a second color image data of a plurality of different element colors usable in an image device for outputting an image A color conversion table creating apparatus for creating a color conversion table to be defined, comprising:
MultipleColorimetry result acquiring means for outputting corresponding plural images to the image device based on the number of second color image data, and measuring the plural images thus output to acquire a colorimetry result;
  Intermediate correspondence determination means for determining an intermediate correspondence between the intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and the second color image data;
  The colorimetric result correspondence relationship between the intermediate color image data and the colorimetric result is determined based on the acquired colorimetric result and the determined intermediate correspondence relationship, and the image is determined based on the colorimetric result correspondence relationship. Use area determining means for determining the use area of the second color image data used by the apparatus;
  Table creation means for creating the color conversion table by determining the correspondence between the first color image data and the use area of the second color image data based on the intermediate correspondence relation and the colorimetric result correspondence relation; A color conversion table creation apparatus comprising:
    18. A plurality of reference points corresponding to a first color image data of a plurality of element colors and a second color image data of a plurality of different element colors usable in an image device for outputting an image A color conversion table creating program that causes a computer to realize a function of creating a color conversion table to be defined.
  An intermediate correspondence determination function of determining an intermediate correspondence between the intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and the second color image data;
  Based on the above determined intermediate correspondenceMultipleColor conversion for converting the number of intermediate color image data into the second color image data, outputting a plurality of corresponding images to the image device, and measuring the plurality of output images to obtain a color measurement result With result acquisition function,
  The present invention is characterized by realizing a table creating function of creating the color conversion table by determining the correspondence between the first color image data and the second color image data based on the intermediate correspondence and the colorimetric result. Color conversion table creation program.
    19. A plurality of reference points corresponding to a first color image data of a plurality of element colors and a second color image data of a plurality of different element colors usable in an imaging device for outputting an image A color conversion table creating program that causes a computer to realize a function of creating a color conversion table to be defined.
MultipleA colorimetry result acquiring function of causing a plurality of corresponding images to be output to the image device based on a number of second color image data, and measuring the plurality of output images to acquire a colorimetry result;
  An intermediate correspondence determination function of determining an intermediate correspondence between the intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and the second color image data;
  The colorimetric result correspondence relationship between the intermediate color image data and the colorimetric result is determined based on the acquired colorimetric result and the determined intermediate correspondence relationship, and the image is determined based on the colorimetric result correspondence relationship. A use area determining function of determining the use area of the second color image data used by the apparatus;
  A table creating function of creating the color conversion table by determining the correspondence between the first color image data and the use area of the second color image data based on the intermediate correspondence relationship and the colorimetric result correspondence relationship; A color conversion table creation program characterized by realizing.
    20. The above claim 18 or claimTo 19The medium which recorded the color conversion table creation program of a statement.
Detailed Description of the Invention
      [0001]
    Field of the Invention
  The present invention relates to a color conversion table creating method, a color conversion table creating apparatus, a color conversion table creating program, and a medium storing the color conversion table creating program.
      [0002]
    [Prior Art]
  An image composed of three element colors of R (red), G (green) and B (blue) that can be displayed on a display is a predetermined number of element colors, for example, C (cyan), M (magenta), Y (yellow), When printing with a printer using four colors of K (black) ink, the correspondence between the color image data before conversion and the color image data after conversion used by the printer is defined for a plurality of reference points Color conversion is performed with reference to the color conversion table. The following steps will be taken to create this color conversion table.
      [0003]
  First, color image data composed of RGB is associated with data of an absolute color space (for example, Lab space) which is a device-independent color space according to a defined definition such as sRGB. On the other hand, representative tone values are selected stepwise from the tone values of each color of ink, and patches for all combinations of each color and each tone value are printed. Therefore, in the case of selecting gradation values of five levels, a printer that performs printing using four colors of ink prints patches of the fourth power of five. Next, colorimetry is performed on all the patches by the colorimeter, and the combination of the CMYK tone values is associated with each component value of the Lab space. Then, the distribution areas of the colorimetric results of all the patches become the color gamut that can be expressed by the printer. Then, among the color measurement results of all the patches, a plurality of color measurement results close to the data of the Lab space associated with the color image data of RGB are extracted, and the color image data of RGB is extracted using interpolation operation. A color conversion table is created by finding the correspondence with color image data of CMYK.
  Note that CMY ink and K ink can be partially replaced with each other, so even if the color image data consisting of RGB is the same, there will be a plurality of corresponding color image data consisting of CMYK. . Therefore, by setting the condition of the use ratio of K ink to CMY ink, color image data consisting of CMYK is determined as one.
      [0004]
    [Problems to be solved by the invention]
  The conventional color conversion table creating method described above has the following problems.
  That is, when the number of types of ink used by the printer increases, the number of patches increases rapidly, and there is a problem that the task of printing patches and measuring colors to create a color conversion table becomes difficult. For example, in the case of a printer using six colors of ink, it is necessary to print and measure patches of 5 to the sixth power, which is 25 times more labor than a printer using four colors of ink . Further, among all the combinations of each color and each gradation value, there are combinations that exceed the limitation of the ink deposition amount, and combinations that are not used at the time of printing due to the K generation condition or the light and dark ink separation condition.
  The present invention has been made in view of the above problems, and a method for creating a color conversion table, a color conversion table creation apparatus, a color conversion table creation program, and a color that can reduce the number of colorimetry of an image for creating a color conversion table. An object of the present invention is to provide a medium storing a conversion table creation program.
      [0005]
    [Means for Solving the Problems]
  In order to achieve the above object, the present invention relates to a first color image data comprising a plurality of element colors and a second color image data comprising a plurality of other element colors usable in an imaging device for outputting an image A color conversion table creating method for creating a color conversion table for defining a plurality of reference points in correspondence with the intermediate color image data, the intermediate color image data comprising a smaller number of intermediate element colors than the element colors of the second color image data And an intermediate correspondence determining step of determining an intermediate correspondence with the second color image data, and the determined intermediate correspondence.MultipleColor conversion for converting the number of intermediate color image data into the second color image data, outputting a plurality of corresponding images to the image device, and measuring the plurality of output images to obtain a color measurement result And a table creating step of creating the color conversion table by determining the correspondence between the first color image data and the second color image data based on the result acquisition step and the intermediate correspondence and the color measurement result. As a configuration to be equipped.
      [0006]
  First, an intermediate correspondence relationship between intermediate color image data consisting of a smaller number of intermediate element colors than element colors of the second color image data and the second color image data is determined. Next, based on the determined intermediate correspondenceMultipleA number of intermediate color image data are color converted to second color image data, and a plurality of corresponding images are output to the imaging device. Further, the plurality of output images are subjected to color measurement to acquire a color measurement result. Then, in the table creating step, the correspondence between the first and second color image data (the first color image data and the second color image data, hereinafter the same) is determined based on the intermediate correspondence and the color measurement result. Create a color conversion table.
  That is, each of the element colors of the second color image data isPictureIt is not necessary to output an image and measure the color, but each of the intermediate element colors of a smaller number than the element colors of the second color image dataPictureBy outputting an image and performing colorimetry, the number of colorimetry can be reduced.
      [0007]
  Here, various image devices to which the present invention can be applied are considered. For example, a printing device such as a printer that outputs an image by printing may be used, or a display that outputs an image by display may be used. . Further, the second color image data usable in the imaging device may be data used as it is in the imaging device, or data used in the imaging device after the predetermined conversion is performed. Such data may be included in the second color image data that can be used in the imaging device according to the present invention.
  Various element colors of the second color image data may be considered, for example, four colors consisting of CMYK, or six colors obtained by adding light cyan (c) and light magenta (m) to CMYK. Various element colors of the first color image data may be considered. For example, it may be composed of each component of RGB, or may be composed of luminance data, blue color difference data and red color difference data, and lightness data It may be composed of two types of chromaticity data.
In the color measurement result acquiring step, a plurality of intermediate color image data provided with a plurality of density steps for each of the intermediate element colors based on the intermediate correspondence determined in the intermediate correspondence determining step is used as the second color image The color conversion to data may be performed, a plurality of corresponding images may be output to the image device, and the plurality of output images may be measured to obtain a measurement result.
      [0008]
  Another step may be added before performing the table creation step. As an example, in the use area determination step, the use area of the second color image data used by the imaging device is determined based on the color measurement result acquired in the color measurement result acquisition step, and in the table creation step The color conversion table may be created by determining the correspondence between the use area and the first color image data.
  Since the color gamut that can be expressed by the image device can be known from the color measurement result obtained by measuring a plurality of images based on a plurality of intermediate color image data, the color gamut to be used by the image device can be easily made It can be selected and the convenience is improved. For example, if only the color gamut in which the image output from the image device has high image quality is determined as the use area, the image quality can be further improved.
      [0009]
  The color measurement result may be a component value of a device-independent color space. That is, it is possible to provide an example of the colorimetric result acquired in the colorimetric result acquiring step, and to determine the color gamut used by the imaging device based on the colorimetric result based on the device-independent color space. It is possible to select the use area of the color gamut of the imaging device more easily.
      [0010]
  In the use area determination step, the gradation value of all the element colors in the second color image data is on the low gradation side, and the graininess of the same element color of the image output from the image device is noticeable The use area of the second color image data may be determined except for the granular appearance area. That is, in the image output from the image device, since the predetermined area in which the graininess of the element color is noticeable is removed from the use area, the graininess of the element color becomes inconspicuous, and the image quality can be improved. At that time, except for the predetermined grainy appearance area where the black graininess of the image output from the image device is noticeable, with the gradation values of all the element colors on the low gradation side among the second color image data. The use area of the second color image data may be determined. As for the black color, the graininess is particularly noticeable in the image, so the image quality can be improved by excluding the area where the black graininess is noticeable.
      [0011]
  As an example of the intermediate correspondence determining step, in the intermediate correspondence determining step, the intermediate color data of the second color image data in the range which can be output by the image device is selected as an example of the intermediate correspondence determining step. It is configured to be associated with image data. That is, since color conversion is not performed to an area which can not be output by the image device, color measurement results of a plurality of images output from the image device can be effectively used to create a color conversion table for more accurate color conversion. .
  Here, when the imaging device is a printer, it is preferable to associate data in the printable range of the second color image data with the intermediate color image data. In the case of a printer that performs printing by discharging a plurality of inks, it is sufficient to associate data of the second color image data that falls within the limitation of the ink ejection amount with the intermediate color image data. Then, color measurement results of a plurality of images printed from the printer can be effectively used, and a color conversion table capable of performing color conversion with higher accuracy can be created.
      [0012]
  In the intermediate correspondence determination step, the intermediate color image data and the second color image data are in a one-to-one relationship, and the colorimetric result acquired in the colorimetric result acquiring step is the same intermediate value. The intermediate correspondence relationship may be determined so as to have a one-to-one relationship with color image data. That is, if the intermediate color image data is different, the second color image data will also be different, and the colorimetric result of the image output based on the second color image data obtained by color converting the intermediate color image data will also be different. Therefore, the color conversion table can be easily created.
      [0013]
  As an example of a table creating step of creating a color conversion table, in the invention according to claim 7, in the table creating step, the correspondence between the first color image data and the intermediate color image data based on the color measurement result. And the correspondence relationship between the first color image data and the second color image data based on the correspondence relationship and the intermediate correspondence relationship to create the color conversion table. Since the intermediate correspondence between the intermediate and second color image data is determined in the intermediate correspondence determining step, when the correspondence between the first and intermediate color image data is determined, the first and the second through the intermediate color image data are determined. The correspondence between the two color image data can be determined.
      [0014]
  In the invention according to claim 8, the color measurement result is each component value of a device independent color space, and an input of the first color image data and each component value of the device independent color space An input-side correspondence determining step of determining a side correspondence is provided, and in the table creating step, the first color image data and the second correspondence are determined based on the input-side correspondence, the colorimetric result, and the intermediate correspondence. The correspondence relationship with color image data is determined to create the color conversion table. Since the colorimetric result is each component value of the device independent color space of the image corresponding to a plurality of intermediate color image data, the input side correspondence between the first color image data and each component value of the device independent color space By determining the relationship, the correspondence between the first and second color image data can be determined based on the input side correspondence, the color measurement result, and the intermediate correspondence.
  As an example, the input-side correspondence can be determined by converting the first color image data into each component value of the device-independent color space according to a predetermined color definition. Furthermore, as another example, in the input side correspondence determination step, a plurality of images based on the plurality of first color image data are measured to obtain a color measurement result, and the input side correspondence relation is obtained based on the color measurement result. You may decide
      [0015]
  As an example of the number of element colors, the element color of the second color image data may be composed of four or more colors, and the intermediate element color may be composed of three colors. The number of colorimetry can be effectively reduced since three colors can be specified as element colors.
  Here, various configurations can be considered for the intermediate element color. For example, the intermediate element color may be a three-element color consisting of CMY and RGB, or may be a three-element color consisting of lightness and two types of chromaticity. The element color of the second color image data at that time may be a four-element color consisting of CMYK, or may be a six-element color to which cm is added, and further Dy (dark yellow). It may be seven added element colors.
  Of course, if the number of element colors of the second color image data is five or more, by setting the intermediate element colors to four, the number of colors to be measured is small even if the intermediate element colors are not three colors. There is no difference in what can be done.
      [0016]
  The method of creating a color conversion table according to each of the above-described steps may be applied to the case where the image device is a printing device as in the invention according to claim 10. According to the configuration, the number of colors can be reduced, and the color gamut to be printed by the printer can be easily selected.
  Here, in the case of a printer that performs printing by discharging a plurality of inks, it is sufficient to associate data of the second color image data that falls within the limitation of the ink ejection amount with the intermediate color image data. Then, color measurement results of a plurality of images printed from the printer can be effectively used, and a color conversion table capable of performing color conversion with higher accuracy can be created.
      [0017]
  By the way, another process may be added before performing the table creation process. As an example thereof, as in the invention according to claim 11, in the second intermediate correspondence determination step, the second intermediate of the second intermediate / intermediate color image data consisting of a smaller number of second intermediate element colors than the intermediate element colors The correspondence relationship is determined, and in the table creation step, the correspondence relationship between the first and second color image data is determined based on the intermediate correspondence relationship, the second intermediate correspondence relationship, and the color measurement result to create a color conversion table. It is also good. Since the correspondence between the intermediate and second color image data can be obtained through the second intermediate color image data based on the intermediate correspondence and the second intermediate correspondence, it is possible to create a color conversion table. Therefore, even with this method, the number of colors can be reduced.
      [0018]
  As an example of the configuration for determining the use color gamut of the image device in the above method, the use area determination step measures the second intermediate color image data and the color measurement result based on the color measurement result and the second intermediate correspondence relationship. The color result correspondence relationship is determined, and the use area of the second color image data to be used by the imaging device is determined based on the determined colorimetry result correspondence, and in the table creation step, The color conversion table may be created by determining the correspondence between the one color image data and the use area of the second color image data.
  Since the color gamut that can be represented by the image device can be known from the colorimetric result correspondence relationship corresponding to the second intermediate color image data, the color gamut to be used by the image device can be easily selected by providing the present use area determination step. To improve convenience.
  The second intermediate element color may be set to a smaller number than the intermediate element color. For example, the element color of the second color image data may be composed of five or more colors, the intermediate element color may be composed of four colors, and the second intermediate element color may be composed of three colors.
  Further, even if the invention is applied to a printer as in the invention according to claim 13, the number of colors can be reduced, and a color gamut to be printed by the printer can be easily selected.
      [0019]
  By the way, the invention according to claim 14 may be configured as an example of another configuration in which the color conversion table is created by obtaining the colorimetric result correspondence relationship. Also in this configuration, the correspondence between the first color image data consisting of a plurality of element colors and the second color image data consisting of a plurality of different element colors that can be used in the image device that outputs the image is specified for a plurality of reference points Create a color conversion table.
      [0020]
  In the color measurement result acquisition process, MultipleBased on the number of second color image data, a plurality of corresponding images are output to the image device, and the plurality of output images are subjected to color measurement to acquire a color measurement result. In the intermediate correspondence determining step, an intermediate correspondence between intermediate color image data consisting of a smaller number of intermediate element colors than the element colors of the second color image data and second color image data is determined. In the use area determination step, the colorimetric result correspondence relationship between the intermediate color image data and the colorimetric result is obtained based on the acquired colorimetric result and the determined intermediate correspondence relationship, and the colorimetric result correspondence is obtained. The use area of the second color image data used by the image device is determined based on the relationship. Then, in the table creating step, the correspondence between the first color image data and the use area of the second color image data is determined based on the intermediate correspondence and the correspondence between the colorimetric results, and the color conversion table is determined. Create
      [0021]
  Since the color gamut that can be expressed by the image device can be known from the colorimetric result correspondence relationship corresponding to the intermediate color image data, the color range to be used by the image device can be easily selected.
In the color measurement result acquiring step, a plurality of corresponding images are output to the image device based on a plurality of second color image data provided with a plurality of density steps for each of the other element colors, and a plurality of outputted The image may be measured to obtain the measurement result.
  Further, even if the invention is applied to a printer as in the invention according to claim 15, it is possible to easily select a color gamut to be printed by the printer.
      [0022]
  The method of creating the color conversion table described above can also be realized in a device having a substantial effect. Therefore, the present invention is also applicable as the device, and in the invention according to claims 16 and 17, basically the same action is obtained. Of course, such an apparatus may be implemented alone or may be implemented together with another method in a state of being incorporated into a certain device, and the concept of the invention includes various aspects. Can be changed as appropriate, such as software or hardware.
      [0023]
  As an embodiment of the idea of the invention, there may be a case where the method of creating a color conversion table is implemented by software. Therefore, the present invention can also be applied as a color conversion table creation program, and the invention according to claims 18 and 19 basically has the same operation.
  Furthermore, when trying to implement the present invention, it is conceivable that a medium storing the above program is distributed, and the program is appropriately read from the recording medium to a computer. Therefore, the present invention can also be applied as a medium having the program recorded thereon, and in the invention according to claim 20, basically the same action is obtained. That is, it is possible to reduce the number of colorimetry of the image for color conversion table creation, and to easily select the color gamut to be used by the imaging device.
  Of course, it goes without saying that the configurations described in claims 2 to 13 and 15 can also be made to correspond to the device, the program, and the medium storing the program.
      [0024]
  Here, the recording medium may be a magnetic recording medium or a magneto-optical recording medium, and the same can be considered for any recording medium developed in the future. Further, even when a part is software and a part is realized by hardware, the concept of the present invention is not completely different, and a part is recorded on a recording medium, and as needed, as appropriate. It includes those in the form of reading. Furthermore, the replication stages of the primary copy, the secondary copy, etc. are completely the same without any doubt.
      [0025]
    【Effect of the invention】
  As described above, according to the inventions of claims 1, 11, 16 and 18, it is possible to reduce the number of colorimetry of the image for color conversion table creation.
  Further, according to the invention of claims 2 and 12, it is possible to easily select the color gamut to be used by the image device.
  Furthermore, according to the third aspect of the present invention, it is possible to more easily select the use area of the color gamut of the imaging device.
      [0026]
  Furthermore, according to the fourth aspect of the present invention, it is possible to create a color conversion table capable of improving the image quality.
  Furthermore, according to the fifth aspect of the present invention, it is possible to create a color conversion table capable of performing color conversion with higher accuracy.
  Furthermore, according to the invention of claim 6, the color conversion table can be easily created.
      [0027]
  Furthermore, according to the invention concerning Claim 7, an example of a table preparation process can be provided.
  Further, according to the invention of claim 8, it is possible to provide an example of determining the correspondence between the first color image data and the second color image data.
  Furthermore, according to the invention of claim 9, it is possible to effectively reduce the number of colorimetry of the image.
  Further, according to the inventions of claims 10 and 13, the color measurement number of the patch for creating the color conversion table can be reduced, and the color gamut to be printed by the printer can be easily selected.
      [0028]
  Furthermore, according to the inventions of claims 14, 17, and 19, it is possible to easily select the color gamut to be used by the imaging device.
  Furthermore, according to the invention of claim 15, it is possible to easily select the color gamut to be printed by the printer.
  Furthermore, according to the invention of claim 20, it is possible to provide a medium on which a color conversion table creation program useful for creating a color conversion table is recorded.
      [0029]
    BEST MODE FOR CARRYING OUT THE INVENTION
  Hereinafter, embodiments of the present invention will be described in the following order.
(1) Outline of color conversion table creation method:
(2) Configuration of color conversion table creation device:
(3) Determination of input side correspondence:
(4) Determination of intermediate correspondence:
(5) Acquisition of color measurement results:
(6) Determination of use area:
(7) LUT creation:
(8) Second embodiment:
(9) Third Embodiment:
      [0030]
(1) Outline of color conversion table creation method:
  FIG. 1 is a diagram for explaining an outline of a color conversion table creating method according to the first embodiment of the present invention.
  The personal computer (PC) 10 performs color conversion with reference to a color conversion table called a LUT (look-up table) that defines correspondence between color image data before and after color conversion for a plurality of reference points. In this embodiment, color conversion is performed on first color image data (hereinafter referred to as RGB data) composed of three RGB element colors into second color image data (hereinafter referred to as CMYK cm data) composed of six element colors CMYKcm. Suppose that a LUT is created. Here, the RGB data is data for causing a display (not shown) provided in the PC 10 to display and output. The printer 20, which is an image device that outputs an image, is a color inkjet printer, and uses CMYK cm data to print with the corresponding CMYK cm ink.
      [0031]
  Both RGB data and CMYK cm data (described as RGB / CMYK cm data, hereinafter the same) are 256 gradations in which 8 bits of each of RGB or CMYK cm are allocated to pixels in a dot matrix shape. Of course, the number of gradations can be set variously as appropriate. For example, 1024 gradations or 100 gradations may be used. Also, the number of gradations of RGB / CMYK cm data may be different.
  Here, in order to prevent the data amount from becoming enormous, a LUT that defines the correspondence of RGB / CMYK cm data at the 17th cube of 17 reference points is created and used by the PC 10. Therefore, 17 cubed pieces of data D1 corresponding to RGB / CMYK cm data are created, and a LUT is created. Of course, the number of reference points can be set variously as appropriate, and may be, for example, 33 cubed. In the present embodiment, CMYKcm data of 256 gradations are sent to the printer 20 after being converted to two gradations by halftone processing.
      [0032]
  In order to create the LUT, it is necessary to measure the patches 21 which are a plurality of images printed by the printer 20. In the present embodiment, a plurality of patches 21 based on a plurality of CMYKcm data, each of which has five steps for each density of CMY colors, is subjected to colorimetry by the colorimeter 22 to obtain 5 3 sample data (colorimetry results) Get D2. Of course, various devices can be used other than using a colorimeter, for example, a color scanner capable of capturing RGB values may be used.
  The sample data D2 includes intermediate color image data (hereinafter referred to as CMY data) composed of CMY three element colors less than CMYK cm and Lab space (device independent color space) obtained by the colorimeter 22. It is data which matches each component value L (brightness), a, b (both chromaticity). Then, based on the sample data D2, create data D3 in which target color data Labout in the color gamut to be used by the printer 20 is associated with CMY data, and create data D1 for LUT based on the data D3. become. Further, data D1 corresponding to CMY / CMYK cm data is also used to create data D1 for the LUT. CMY is the intermediate element color according to the present invention, and the data D4 is data defining the intermediate correspondence relationship of CMY / CMYK cm data (hereinafter also described as the 3-6 color relationship in the first and second embodiments) Become.
      [0033]
  In addition, since the printer 20 can not represent an image for all input color image data, the printer 20 also uses data D5 in which the input and output of color image data are associated with each other with reference to the Lab space. The data D1 for LUT is created together with the data D6 in which the data and the Lab value are associated with each other. Here, the data D5 corresponds to the Lab value Labin of the color image data on the input side and the Lab value Labout of the color image data on the output side, and the data D6 corresponds to the RGB data and Labin. become. Then, in the data D3 created based on the sample data D2, Labout and CMY data are associated.
      [0034]
  FIG. 2 is a block diagram showing each step of the color conversion table creating method.
  In the input-side correspondence determining step S11, RGB data is associated with Lab space data according to the definition of sRGB, and data D6 defining the input-side correspondence between RGB data and each component value of the Lab space is determined. Since the input side correspondence relationship may be determined by the table creation step S15 described later, the input side correspondence relationship determination step S11 may be provided after the steps S12 to S14, and the step S11 corresponds to the table creation step S15. May be included in Of course, if the input side correspondence relationship between RGB data and Lab values has already been determined, it is possible to omit this step S11.
      [0035]
  In the intermediate correspondence determining step S12, data D4 defining the 3-6 color relationship of CMY / CMYK cm data is determined. Here, what is determined here is the so-called K generation condition in which CMY data is replaced with CMYK data, and the light and dark ink separation condition in which C and M data are replaced with Cc and Mm data, respectively. At this time, only data that falls within the ink injection amount restriction is used for the CMYKcm data so as not to exceed the ink injection amount restriction which is a printable range by the printer. As a result, combinations of each color and each gradation value that are not used during printing can be removed, so color measurement results of a plurality of patches printed from the printer are not wasted, and color conversion can be performed with high accuracy. Possible LUTs can be created. Also, the 3-6 color relationship is determined so that the CMY / CMYK cm data has a one-to-one relationship, and the colorimetric result acquired in the colorimetric result acquisition step S13 has a one-to-one relationship with the CMY data. . Then, if the CMY data is different, the CMYKcm data will also be different, and the colorimetry results of the patches printed based on the CMYKcm data obtained by color-converting the CMY data will also be different, which facilitates the creation of the LUT.
      [0036]
  In the color measurement result acquiring step S13, 5 cubic = 5 5 CMY data provided in 5 density steps for each of CMY based on the determined 3-6 color relationship is subjected to color conversion into CMYKcm data, and a plurality of corresponding A patch is printed on a printer, and all of the printed plurality of patches are measured by a colorimeter to acquire a color measurement result based on Lab space. That is, five representative gradation values are selected from gradation values of each CMY, patches for all combinations of each color and each gradation value are printed, color measurement is performed, and a combination of CMY gradation values is Lab. Sample data D2 associated with each component value of space is acquired.
  In the conventional method, five representative gradation values are selected from the gradation values of each color of ink, and 5 6 = 15625 patches are printed for all combinations of each color and each gradation value. It will measure. Therefore, in a printer that performs printing using six colors of ink, the effort to print and measure patches is significantly reduced to 125/15625 = 1/125. In addition, since it is possible to specify the color if there are three colors as the intermediate element color, the number of colorimetric measurements can be effectively reduced.
      [0037]
  In the use area determination step S14, the use area of CMYK cm data used by the printer is determined based on the color measurement result. First, the color gamut that can be expressed by the printer can be determined from the distribution area of the colorimetric results of all the patches. Next, based on the determined color gamut, data D5 is determined which associates Labin associated with RGB data with target color data Labout in the area used by the printer. Further, in the present embodiment, data D3 which associates target color data Labout with CMY data is determined from sample data D2 having a colorimetric result. At that time, a plurality of color measurement results close to the target color data Labout are extracted from the color measurement results of all the patches, and Labout is associated with the CMY data by using an interpolation operation.
      [0038]
  In the table creating step S15, the correspondence between the RGB data and the use area of the CMYK cm data is determined based on the 3-6 color relationship and the colorimetric result to create the LUT. First, the correspondence between RGB / CMY data is determined based on the input-side correspondence, data D5 in which Labin / out is associated, and data D3 created based on the colorimetric result. Then, based on the correspondence relationship and the 3-6 color relationship, the correspondence relationship of RGB / CMYK cm data can be determined to create a LUT.
      [0039]
(2) Configuration of color conversion table creation device:
  The present color conversion table creating method is to create a LUT by printing a large number of patches and performing color measurement to create various data D1 to D6. Therefore, it is preferable to implement the method using a computer. In this case, the computer constitutes a color conversion table creating apparatus, and a program to be executed is a color conversion table creating program. FIG. 3 shows a computer constituting the color conversion table creating apparatus together with a printer. In the present embodiment, the created LUT is used to create the LUT using the PC 10 capable of color conversion of color image data as it is, but the LUT may be created using another computer. Of course, the computer does not have to be a PC, and a computer having a general configuration can be employed.
  The PC 10 includes a CPU 11 that controls the entire PC 10 via the system bus 10 a. The ROM 12, the RAM 13, the CD-ROM drive 15, the flexible disk (FD) drive 16, various interfaces (I / F) 17 a to e, etc. are connected to the bus 10 a. The HD 14 is also connected via a hard disk (HD) drive.
      [0040]
  The HD 14 stores an operating system (OS) as software, an application program (APL) capable of creating print data, and the like, and the software is appropriately transferred to the RAM 13 by the CPU 11 at the time of execution. Then, the CPU 11 executes various programs while appropriately accessing the RAM 13 as a temporary work area. Although the color conversion table creation program of this embodiment realizes various functions as a type of APL, it may be incorporated in the OS.
  The printer 20 is connected to the printer I / F 17 e via a parallel I / F cable.
      [0041]
  The colorimeter 22 used in the present embodiment expresses a colorimetric value based on the Lab colorimetric system, that is, an L value representing lightness, and hue and saturation by pressing the color detection unit against the patch to be measured. The a and b values can be measured. Note that, since the colorimetric value varies depending on the media on which the patch is printed, a representative plurality of media are selected to print the patch, and the patch is colorimetrically measured for each media. The measured colorimetric value can be sent out via the USB cable as a colorimetric result. Accordingly, the colorimeter 22 is connected to the USB I / F 17a. Of course, for connection between the colorimeter 22 and the PC 10, other connection modes such as RS-232C connection can also be adopted.
      [0042]
  A display 18a for display output is connected to the CRTI / F 17b, and a keyboard 18b and a mouse 18c are connected to the input I / F 17c as operation input devices. Then, the measurement result can be input from the keyboard 18b or the like.
  Furthermore, it is also possible to read the colorimetric result from the FD 16 a storing the colorimetric result via the drive 16.
      [0043]
  The HD 14 storing the color conversion table creating program is a medium storing the color conversion table creating program according to the present invention. The medium is, for example, a CD-ROM, an FD 16a, a magneto-optical disk, a non-volatile memory, etc. It may be Of course, it is also possible to connect the communication I / F 17d such as a modem to the Internet network, access a predetermined server, download the present color conversion table creating program and execute it.
      [0044]
  The printer 20 prints on the media using CMYK cm ink. Of course, a printer that uses inks other than six colors may be employed. In addition, various printing apparatuses such as a bubble type printer that generates bubbles in the ink passage and discharges the ink, a laser printer, and the like can be adopted.
  In the printer 20, a CPU, a ROM, a RAM, an ASIC, communication I / O, I / F, and the like are connected via a bus. The communication I / O is connected to the printer I / F 17 e of the PC 10, and the printer 20 receives a print job composed of data converted to CMYK cm, a page description language, etc. transmitted from the PC 10 via the communication I / O. . The ASIC outputs applied voltage data based on the CMYK cm data to the head driving unit while transmitting and receiving a predetermined signal to and from the CPU. The head drive unit generates an applied voltage pattern to a piezo element incorporated in the print head based on the applied voltage data input from the ASIC, and causes the print head to eject the ink of CMYK cm. A sheet feeding mechanism or a carriage mechanism connected to the I / F sends out the media sequentially to perform a subscanning while appropriately performing a page change operation, or causes the print head to perform a main scan. Then, the CPU controls each part according to the program written in the ROM while using the RAM as a work area.
      [0045]
  In the PC 10, the BIOS is executed on the basis of the above hardware, and the OS and the APL are executed in the upper layer thereof. The OS incorporates various drivers such as a printer driver for controlling the printer I / F 17e, and functions as a part of the OS to execute control of hardware. The printer driver is activated at the time of execution of the printing function of the APL, and can perform two-way communication with the printer 20 via the printer I / F 17e. A GDI (Graphics Device Interface) or the like is incorporated in the OS, and the printer driver receives print data from the APL via the OS, creates a print job to be output to the printer 20, and sends it to the printer 20.
      [0046]
  FIG. 4 schematically shows the configuration of a color conversion table creation program which is one of the APLs. The modules 31 to 35 constituting the program are provided corresponding to the steps S11 to S15, respectively.
  That is, the input-side correspondence determination module 31 causes the PC 10 to realize the function of determining the input-side correspondence. The intermediate correspondence determining module 32 is a K generation processing module that realizes a function of determining a K generation condition, a gray scale separation processing module that realizes a function of determining a gray ink separation condition, and a limit of ink ejection amount. And a implantation restriction processing module for realizing the function of determining the CMYKcm data.
      [0047]
  The color measurement result acquisition module 33 is a patch print module that realizes a function of converting CMY data into CMYK cm data and printing a plurality of corresponding patches on a printer, and a function of acquiring color measurement result Lab values of the patch. It has Lab value acquisition module to realize. The use area determination module 34 determines a color gamut that can be expressed by a printer and realizes a function to associate Labin / out with a target color determination module, and a CMY association module to realize a function to associate Labout with CMY data. Have.
  The table creation module 35 realizes a function of creating a LUT based on the above-described input side correspondence relationship, the 3-6 color relationship, the correspondence relationship of Labin / out, and the correspondence relationship of Labout and CMY data.
      [0048]
(3) Determination of input side correspondence:
  Hereinafter, each process of the color conversion table creating method will be described in detail along with the operation of the PC 10. FIG. 5 shows the input side correspondence determination flow performed by the PC 10 in order to determine the input side correspondence in the input side correspondence determination step.
  When the input side correspondence determination module is activated, a cubic grid of n (n is a positive integer) cubic grid points which are substantially equally spaced along each axis in the RGB color space using a PC Data to be defined is created (step S102; hereinafter, the description of "step" is omitted). For example, if n = 17, 17 cubic grid points provided in 17 steps for each of RGB are defined. Here, representative gradation values are classified into five levels including 0 and 255 from gradation values of each RGB, for example, gradation values 0, 16, 32, ..., 240, 255 for each of RGB. select.
      [0049]
  Next, the PC converts RGB data of grid points into each component value (Labin) of Lab space according to the definition of sRGB (S104). Then, by storing the RGB data and the converted Lab value in a predetermined area of the RAM 13 or the HD 14, data defining the correspondence between the RGB data and each component value of the Lab space on the input side (data D6 in FIG. 1) Are created (S106). Then, RGB data can be associated with Labin. Here, the flow ends.
  Note that instead of using this flow, a plurality of images corresponding to the grid points may be output to the display 18a, and colorimetry may be performed on the same image by the colorimeter 22 to obtain Lab values. . At that time, in order to reduce the number of grid points, for example, 5 cubic grid points of 5 stages provided for each of RGB are defined and measured, and 17 cubic power Lab values are obtained by interpolation calculation with PC. You may get The method of defining grid points is the same as the method of defining grid points in the CMY color space, as described later. Then, a plurality of images corresponding to the grid points are output to the display, the color detection unit of the colorimeter 22 is pressed against each of the images, color measurement is sequentially performed, and the color measurement results for all the images are PC By taking in, it is possible to create data that defines the input side correspondence between RGB data and Lab values. Here, the Lab value can be read from the colorimeter 22 to the PC via, for example, the USB I / F 17a.
      [0050]
(4) Determination of intermediate correspondence:
  FIG. 6 shows an intermediate correspondence determination flow performed by the PC 10 to determine the 3-6 color relationship in the intermediate correspondence determination step.
  When the intermediate correspondence determination module is activated, a K generation condition for replacing CMY data with CMYK data so as to be one to one using a PC is determined (S152). At this time, the K generation condition is determined such that the colorimetric result acquired in the colorimetric result acquiring step also has a one-to-one relationship with CMY data. The PC receives the input of various conditions such as the ink type, and determines the K generation condition according to the input condition. Here, one-to-one refers to a relationship in which, if CMY data is different, CMYK data is also different and colorimetric results are also different.
  The upper stage to the middle stage of FIG. 7 schematically show an example of determining the K generation condition. The figure shows the relationship between the input tone value (relative value) and the output tone value (relative value) at the gray level (C = M = Y). Here, the horizontal axis is black in the left direction (large tone value of CMY) and white in the right direction (small tone value of CMY), and the vertical axis is black in the upper direction (large tone value of CMYK) The downward direction is white (the gradation value of CMYK is small).
      [0051]
  As shown in the upper part of the figure, when the CMY data is not replaced with the CMYK data, all the output gradation values y of CMY with respect to the input gradation value x of the gray level have a relation of y = x. As shown in the middle of the figure, when the CMY data is replaced with the CMYK data, when the input tone value becomes larger than A1, the CMY data is decreased and the decreased amount is replaced with the K data. When the input tone value becomes larger than A2 (A2> A1), CMY data is set to 0 and only K data is increased. This relationship can be expressed by the following equation when C, M, Y, and K represent output gradation values of CMYK, respectively.
    When x ≦ A1,
        C = M = Y = x
        K = 0
    When A1 <x ≦ A2,
        C = M = Y = {A1 / (A1-A2)} (x-A2)
        K = {A2 / (A2-A1)} (x-A1)
    When A2 <y,
        C = M = Y = 0
        K = x
  Of course, the above relational expressions are merely examples, and C, M, and Y may be changed as appropriate.
      [0052]
  Next, dark and light ink color separation conditions for replacing CMYK data with CMYK cm data so as to be one to one by the PC are determined (S154). Here, one-to-one refers to a relationship in which the CMYKcm data are different if the CMYK data are different. In this embodiment, the C and M data are replaced with Cc and Mm data, respectively, and the Y and K data are not changed depending on the light and dark ink separation conditions. The PC accepts the input of various conditions such as the ink type, and determines the dark and light ink separation conditions according to the input conditions. The middle and lower parts of FIG. 7 schematically show an example of determining the dark and light ink color separation conditions.
  As shown in the lower part of the figure, when replacing C and M data with Cc and Mm data, if the input tone value is A3 (A3 <A1) or less, the C and M data is 0, c, m Increase data only. When the input tone value becomes larger than A3, the data of c and m are decreased, and the decreased amount is replaced with the data of C and M. Then, when the input gradation value becomes larger than A4 (A3 <A4 <A1), the data of c and m is set to 0, and only the data of C and M is increased. This relationship can be expressed by the following equation when C, M, c and m output gradation values are represented by C, M, c and m, respectively.
    When x ≦ A3,
        C = M = 0
        c = m = ax (a is a constant greater than 1)
    When A3 <x ≦ A4,
        C = M = {A4 / (A4-A3)} (x-A3)
        c = m = a {A3 / (A3-A4)} (x-A4)
    When A4 <y ≦ A1,
        C = M = x
        c = m = 0
      [0053]
  Here, the gradation values A1 to A4 may be appropriately determined according to various conditions such as the ink type, or may be determined by an operation input to the PC, or the ink type and the gradation value A1 by the PC. It may be determined by referring to a predetermined table in which ~ A4 is associated.
  Of course, when determining the K generation condition and the light and dark ink separation condition, the same condition may be determined by creating a table in which tone values before and after input and output are associated with each other without using an equation.
      [0054]
  Further, the PC is used to limit the ink injection amount so that the CMYKcm data reflecting the K generation condition and the dark and light ink color separation condition become one to one before and after conversion (S156). At that time, the PC receives the input of various conditions such as the type of ink, and performs the ink injection amount restriction processing according to the input conditions. In this embodiment, the total of all of C, M, Y, K, c, m is equal to or less than a predetermined value, where C, M, Y, K, c, m are the ink impact amounts (relative values) of CMYKcm, respectively. To convert data.
      [0055]
  FIG. 8 schematically shows the process of limiting the ink deposition amount, but for easy understanding, the two types of C and M inks are shown as being limited to C + M ≦ 140%. . In the figure, the horizontal axis is the ink hit amount (relative value) of C, and the vertical axis is the ink hit amount (relative value) of M. Grid points provided at five equal intervals for each of C and M Is indicated by a circle. Further, a portion where C + M = 140% is indicated by a solid line, and a portion where C + M = 120% is indicated by a dotted line. In the example of the figure, the grid points P1 to P6 are out of the ink loading amount limitation, and the area outside the ink loading amount limitation including the grid points P1 to P6 is 120% ≦ 1 to 1. It will be moved to a predetermined compression area where C + M ≦ 140%. In addition, each portion of the region of C + M> 120% is moved so as to be compressed 1 to 1 in the lower left direction where the inclination is 1 in the CM plane, and lattice points P1 to P5 at the boundary portion of the color space Is to be moved to a portion where C + M = 140%.
  Then, as shown in the lower part of the figure, the area of C + M> 120% is compressed in the lower left direction, and the ink impact amount becomes C + M ≦ 140% which is a printable range by the printer.
      [0056]
  Then, the CMY data is stored in a predetermined area of the RAM 13 or the like in association with the CMYKcm data which has been subjected to the process of limiting the ink injection amount by reflecting the K generation condition and the light and dark ink separation condition. The data (data D4 in FIG. 1) defining the -6 color relationship is created (S158). Here, this flow ends.
  Then, CMY data of three element colors less than CMYKcm data and CMYKcm data can be correlated one to one, that is, if CMY data are different, CMYKcm data is also different. And, if the CMY data is different, the colorimetric result will also be different. The CMYK cm data is data within a range that can be output by the printer.
      [0057]
(5) Acquisition of color measurement results:
  FIG. 9 is for the printer to print a plurality of patches corresponding to a plurality of CMY data provided in a plurality of density steps for each of the intermediate element colors CMY in the color measurement result acquiring step to acquire the color measurement results of the patches It shows a color measurement result acquisition flow performed by the PC.
  When the color measurement result acquisition module is activated, as shown in FIG. 10, a cubic grid consisting of 5 cubic grid points spaced approximately equally along each axis in the CMY color space is defined using a PC. Data to be created (S202). Here, representative gradation values are classified into five levels including 0 and 255 from gradation values of each CMY, for example, gradation values 0 (0%), 64 (25%), 128 (for CMY, respectively). Choose 50%), 192 (75%), 255 (100%). If coordinates in the CMY color space are represented by (C, M, Y), as shown in the figure, the ends of the CMY color space are (0, 0, 0), (255, 0, 0), (255, 255, 255) , Etc. are also included in the grid points. Although each side of the CMY color space is divided into four equal parts in the figure, the division position and the number of divisions can be appropriately set appropriately.
      [0058]
  Next, the PC converts the color of a plurality of CMY data corresponding to the grid points into CMYK cm data (S204). This process extracts CMYKcm data corresponding to CMY data with reference to data D4 defining the 3-6 color relationship, or acquires a plurality of CMYKcm data close to CMY data from the same data D4 and performs interpolation operation. It can carry out by calculating | requiring CMYKcm data by this. The interpolation operation may be linear interpolation or non-linear interpolation such as spline interpolation.
  Further, a plurality of patches corresponding to the color-converted CMYKcm data are printed on the medium (S206). FIG. 11 shows an example of how a plurality of patches 91 are printed, and each of the patches 91 corresponds to CMY data of each lattice point.
  Then, the colorimeter 22 performs color measurement on the printed patch 91. That is, the color detection unit of the colorimeter 22 is pressed against each of the printed patches, and color measurement is sequentially performed. The PC acquires the colorimetric result based on the Lab space for all of the plurality of patches (S208). That is, Lab values of patches for all combinations of each color and each gradation value are acquired. Here, the Lab value may be read from the colorimeter 22 via the USB I / F 17 a, or the Lab value may be temporarily stored in the FD 16 a and read via the FD drive 16. Further, the Lab value may be acquired by receiving an operation input from the keyboard 18b, or the Lab value may be acquired via a voice input device (not shown).
      [0059]
  Thereafter, CMY data and Lab values are associated with each other and stored in a predetermined area such as the RAM 13 or the like, whereby data in which a combination of CMY tone values is associated with each component value in Lab space (sample data D2 in FIG. 1) Are created (S210). Here, the flow ends. Thus, based on the determined 3-6 color relationship using this flow, color conversion of 5 cubic CMY data provided in 5 density steps for each of CMY into CMYK cm data is performed. A plurality of patches can be printed by the printer, and the printed plurality of patches can be measured to obtain a color measurement result.
      [0060]
(6) Determination of use area:
  FIG. 12 shows a use area determination flow performed by the PC 10 to determine the use area of CMYK cm data used by the printer in the use area determination process.
  When the use area determination module is activated, information about the color gamut that can be expressed by the printer 20 is output to the display 18a or the like using the PC based on the sample data D2 storing the colorimetric results of all the patches ( S252). Of course, the printer 20 may print. Here, the color gamut that can be represented by the printer can be determined from the distribution area of the colorimetric result for the CMY data. For example, the same color gamut can be determined by referring to the sample data D2 and mapping the color corresponding to the CMY data in the screen showing the printer gamut.
  Next, based on the determined color gamut, target color data Labout corresponding to Labin associated with the RGB data is determined. The PC receives Labout on the output side with respect to Labin, which is the input side, by operation input using the keyboard 18b or the mouse 18c, and acquires the input Labout (S254). For example, as shown in FIG. 13, when the output gamut R2 represented by the printer based on the CMYKcm data exists in the input gamut R1 represented by the RGB data on the input side, it is outside the output gamut R2 The point P11 in the existing input gamut R1 is associated with the point P12 in the same output gamut R2. The figure schematically shows the input color gamut and the output color gamut as an aL plane of Lab space, the Lab value of point P11 is Labin, and the Lab value of point P12 is Labout in the area used by the printer. is there.
      [0061]
  Here, when the color gamut to be used by the printer is determined, the predetermined granular appearance region R3 in which the granular feeling of K of the image printed by the printer is noticeable is excluded. The output gamut R4 that can be expressed using only CMY ink is narrower in the high brightness direction than the output gamut R2 with CMYK cm ink in the low brightness region, but the granular appearance region R3 is CMYKcm data The gradation values of all the element colors CMYKcm among them are on the low gradation side and outside the general output gamut R4. As described above, since the predetermined area in which the granular feeling of K is noticeable is removed from the use area, the granular feeling of black becomes inconspicuous, and the image quality can be improved.
  Of course, graininess may be noticeable even for relatively dark C and M, so C, M of the image to be printed by the printer when the tone value of all the element colors CMYKcm in the CMYKcm data is on the low tone side. The granular appearance region where the granular feeling of K, K is noticeable may be removed. Then, the graininess of C, M, and K becomes inconspicuous, and the image quality can be improved.
  Then, the data D5 shown in FIG. 1 is created by storing the Labin / out in a predetermined area such as the RAM 13 in a corresponding manner in the PC (S256). The processes of S254 and S256 are repeated for all the Labins stored in the data D6 that defines the input side correspondence relationship.
  If the colorimetric result is the result corresponding to the CMYKcm data, it is necessary to represent the color gamut that can be expressed by the printer in six dimensions, making it difficult to grasp the same color gamut. As in the present embodiment, the color gamut that can be expressed by the printer can be expressed in three dimensions by using the colorimetric result corresponding to the data of three colors CMY of fewer than six colors of CMYK cm, and the same color gamut Can easily be selected, and Labout, which is a color gamut to be used by the printer, can be easily selected.
      [0062]
  Further, in this embodiment, a plurality of colorimetry results close to the target color data Labout stored in the data D5 of FIG. 1 from the sample data D2 having the colorimetry results corresponding to the CMY data using the PC are CMY data Along with (S258). Next, CMY data corresponding to the same Labout is determined using interpolation calculation (S260). The interpolation operation may be linear interpolation or non-linear interpolation such as spline interpolation. Then, the data D3 shown in FIG. 1 is created by correlating the Labout and the CMY data and storing them in a predetermined area such as the RAM 13 (S262). The processes of S258 to S262 are repeated for all the Labouts stored in the data D5 that defines the correspondence between the input and output of the color image data. Here, the flow ends. As described above, using this flow, it is possible to easily select the color gamut to be used by the printer based on the colorimetric result.
      [0063]
(7) LUT creation:
  FIG. 14 shows a table creation flow performed by the PC 10 in order to create a LUT by determining the correspondence between RGB / CMYK cm data in the table creation step.
  When the table creation module is activated, data that associates RGB data with target color data Labout is created using a PC (S302). Since data D6 defining the correspondence between RGB data and Labin on the input side and data D5 correlating Labin / out are created, Labin corresponding to RGB data is acquired from data D6 as shown in FIG. When Labout corresponding to Labin having the same value as the acquired Labin is acquired from the data D5, the same data D7 can be created. Here, since Labout is within the use area of the CMYKcm data, the correspondence between the first color image data and the use area of the second color image data is determined to create the LUT. In addition, since Labout has a grainy appearance region removed, the graininess of the image printed using the created LUT is not noticeable.
      [0064]
  Next, data D8 which associates RGB / CMY data is created (S304). Since data D3 for associating Labout with CMY data is created, if Labout corresponding to RGB data is acquired from data D7 and CMY data corresponding to Labout having the same value as acquired Labout is acquired from data D3, Data D8 can be created. That is, the correspondence between the first and intermediate color image data is determined based on the data D3 on which the color measurement result is reflected.
      [0065]
  Further, data D1 to associate RGB / CMYK cm data is created (S306). Since data D4 defining the 3-6 color relationship is created, CMY data corresponding to RGB data is obtained from data D8, and CMYKcm data corresponding to CMY data having the same value as the obtained CMY data is obtained from data D4 If CMYKcm data corresponding to a plurality of CMY data to be acquired or close to acquired CMY data is acquired from the data D4 and the CMYKcm data is determined by interpolation calculation, the data D1 can be created. That is, the correspondence between the first color image data and the use area of the second color image data is determined based on the correspondence between the first and intermediate color image data and the intermediate correspondence.
  Finally, based on the data D1, a LUT of a predetermined format is created (S308). Then, the correspondence between the first color image data of a plurality of element colors RGB and the second color image data of a plurality of different element colors CMYKcm that can be used by the printer that outputs the image is defined for a plurality of reference points A LUT will be created. Here, the flow ends.
      [0066]
  Although FIG. 15 describes data D7 and D8 once as data D7 and D8 for easy understanding, even if data D7 and D8 are not generated in a predetermined area such as RAM 13, data D3 to D6 may be used. Data D1 for LUT can be created. For example, Labin corresponding to RGB data is acquired from the data D6, next, Labout corresponding to the Labin having the same value as the acquired Labin is acquired from the data D5, and further, it corresponds to Labout having the same value as the acquired Labout. When CMY data is acquired from data D3 and CMYKcm data corresponding to a plurality of CMY data close to the acquired CMY data is acquired from data D4 and CMYKcm data is determined by interpolation calculation, data D1 corresponding to RGB / CMYKcm data is created can do.
      [0067]
  The LUT created as described above is used in the printing process generally performed by a general purpose computer. For example, the user can print the image on the printer by operating a mouse or the like under execution of APL which can execute retouching of a color image and the like. At the time of printing such an image, the created LUT is referred to. The color image data created by the APL is dot matrix data in which each color component of RGB is tone-represented, and conforms to the sRGB standard. A printer driver incorporated in the OS converts RGB data into multi-gradation CMYK cm data by volume interpolation with reference to a LUT stored in the HD. If the printer can execute halftone processing, the multi-tone CMYKcm data is output to the printer as it is, otherwise the printer driver performs halftone processing and then outputs it to the printer. As described above, the multi-tone CMYKcm data which is the second color image data may be data to be used in the printer after the predetermined halftone processing is performed, and the multi-tone CMYK cm as in this case may be used. Even data is included in the second color image data according to the present invention. Since color image data is not converted to a region where graininess such as K is noticeable at the time of color conversion, it is possible to print high-quality images.
      [0068]
  As described above, the table creation flow can be used to create the LUT by determining the correspondence between the first and second color image data based on the input side correspondence, the color measurement result, and the intermediate correspondence. . At that time, it is not necessary to print patches provided with a plurality of density steps for each of CMYKcm as in the conventional method, and to measure and print patches provided with a plurality of density steps for each of the intermediate element colors CMY having a smaller number than CMYKcm. It will be colored. Therefore, it is possible to reduce the color measurement number of the patch for LUT creation, and the operation of printing and measuring the patch is also greatly reduced. In addition, by predetermining the relationship between CMY / CMYK cm data, it is possible to select only the area to be used from the color gamut that can be expressed by the printer and create the LUT. Furthermore, since color conversion is not performed beyond the ink injection amount limitation of the printer, color measurement results of a plurality of patches printed from the printer are effectively used to perform color conversion with higher accuracy. , K, etc. can be made inconspicuous, and the image quality can be further improved.
      [0069]
(8) Second embodiment:
  In addition, various configurations are possible for the computer and the image device that can be used when implementing the color conversion table creation method of the present invention.
  For example, the printer may be integrated with a computer, or may be a dedicated product that prints only single-color images. In the case of a printer that performs printing using four or more colors, it becomes possible to reduce the number of colorimetric values by selecting three intermediate element colors.
  Further, various color measurement results can be adopted for the patch in addition to the Lab value. For example, each Luv value of Luv space may be sufficient, each RGB value of RGB color space may be sufficient, and each component value of the color space defined by other XYZ space may be sufficient. Of course, it is also possible to use each component value in a predetermined color space other than the absolute color space as the color measurement result.
      [0070]
  By the way, it is also possible to create the LUT by changing the order of the above-described intermediate correspondence determination process and the color measurement result acquisition process. FIG. 16 is a block diagram showing each step of the color conversion table creating method according to the second embodiment, and FIG. 17 is an explanatory diagram for explaining the outline of the method.
  In the input side correspondence determination step S21, the RGB data is associated with the data in the Lab space, and the input side correspondence between the RGB data and each component value in the Lab space is determined. In this process, the flow shown in FIG. 5 can be used as it is to determine the data D12 that associates RGB data with Labin, so detailed description will be omitted.
      [0071]
  In the color measurement result acquisition step S22, based on the 5 ^ 6 CMYKcm data provided with 5 density steps for each of the 6 colors of CMYKcm, the corresponding plurality of patches are printed by the printer, and the plurality of printed patches 21 are measured. Colorimetry is performed by the color unit 22 to acquire a colorimetric result (sample data D13) based on the Lab space. This process can be implemented using the same flow as FIG.
  That is, using the PC, data is defined that defines five sixth power grid points that are substantially equally spaced along each axis in the CMYKcm color space (corresponding to S202). The next S204 is omitted, and a plurality of patches corresponding to the CMYKcm data of each lattice point are printed on the medium (corresponding to S206). Then, the colorimeter 22 performs color measurement on the printed patch. The PC acquires a colorimetric result based on the Lab space for all of the plurality of patches (corresponding to S208). Thereafter, the sample data D13 is created by correlating the CMYKcm data with the colorimetric result (Lab value) and associating the combination of the CMYKcm tone value with each component value of the Lab space (corresponding to S210).
      [0072]
  In the intermediate correspondence determining step S23, the 3-6 color relation (intermediate correspondence) between CMY data (intermediate color image data) consisting of three colors and CMYKcm data consisting of six colors is determined to be a one-to-one relation. Do. Here, the K generation condition and the light and dark ink color separation conditions are determined, and for the CMYKcm data, only data that falls within the ink injection amount limitation is used. In this process, since the data D14 defining the 3-6 color relationship can be determined using the flow shown in FIG. 6 as it is, detailed description will be omitted.
      [0073]
  In the use area determination step S24, the colorimetric result correspondence relationship between the CMY data and the colorimetric result based on the acquired colorimetric result and the determined 3-6 color relationship (hereinafter also described as CMY-Lab relationship) Are determined, and the use area of CMYK cm data used by the printer is determined based on the CMY-Lab relationship. This process can be implemented using the use area determination flow shown in FIG.
  First, using a PC, a plurality of colorimetric results close to CMYK cm data corresponding to CMY data stored in data D14 defining the 3-6 color relationship are acquired from sample data D13 (S402). Next, the Lab value corresponding to the CMY data is determined using interpolation calculation (S404). Then, the CMY data and the Lab value are associated with each other to create data D15 defining the CMY-Lab relationship (S406).
      [0074]
  Thereafter, using the same flow as in FIG. 12, Labin / out are associated, and Labout and CMY data are associated. That is, information about the color gamut that can be expressed by the printer 20 is output to a display etc. using a PC (corresponding to S252), and the color gamut that can be expressed by the printer is determined from the distribution area of Lab values for CMY data. Do. Next, Labout of the output side with respect to Labin which is the input side is acquired, and data D16 which associates Labin / out is created (corresponding to S254 to S256). Note that, if it is necessary to express the color gamut that can be expressed by the printer in six dimensions, it is difficult to grasp the same color gamut when using the colorimetric result corresponding to the CMYKcm data. On the other hand, the use of data defining the CMY-Lab relationship corresponding to CMY three-color data less than six CMYKcm colors allows three-dimensional representation of the printer's expressible gamut. Since it is easy to grasp the same color gamut, it is possible to easily select Labout, which is a color gamut to be used by the printer. For example, if Labout is determined so as to exclude a predetermined granular appearance region where the granular appearance of K is noticeable, the image printed by the printer becomes inconspicuous in the black granular appearance, and the image quality can be improved.
  Further, data defining a plurality of CMY-Lab relationships close to Labout stored in the data D16 is extracted from the data D15 defining the CMY-Lab relationship (corresponding to S258). Next, CMY data corresponding to the same Labout is determined using an interpolation operation (corresponding to S260). Then, Labout and CMY data are associated with each other to create data D17 (corresponding to S262).
      [0075]
  In the table preparation step S25, the correspondence between the RGB data and the use area of the CMYK cm data is determined based on the correspondence on the input side, the CMY-Lab relation, and the 3-6 color relation to create the LUT. This process can be implemented using the same flow as that of FIG.
  First, using a PC, data D12 and D16 having Labin are referenced to create data that associates RGB data with Labout (corresponding to S302). Next, data corresponding to RGB / CMY data is created with reference to the same data and data D17 correlating Labout and CMY data (corresponding to S304). That is, the correspondence between the first and intermediate color image data is determined based on the data D17 in which the correspondence between the colorimetric results is reflected.
      [0076]
  Further, data D11 corresponding to RGB / CMYK cm data is created with reference to the same data and data D14 defining the 3-6 color relationship (corresponding to S306). Finally, based on the data D11, a LUT of a predetermined format is created (corresponding to S308). That is, based on the correspondence between the first and intermediate color image data and the intermediate correspondence, the correspondence between the first color image data and the use area of the second color image data is determined to create the LUT.
  According to the above flow, although the colorimetry number of the patch for LUT creation does not decrease, the CMY-Lab relationship corresponding to the CMY data indicates the color range that can be expressed by the printer, so the color range that can be expressed by the printer can be selected. It is possible to easily select only the area to be used and create the LUT.
      [0077]
(9) Third Embodiment:
  In addition, it is possible to reduce the number of colorimetry of a patch by printing a patch based on data consisting of four intermediate component colors CMYK instead of CMYKcm data. FIG. 19 is a block diagram showing each step of the color conversion table creating method according to the third embodiment, and FIG. 20 is an explanatory diagram for explaining the outline of the method.
  In the input-side correspondence determining step S31, the RGB data is associated with the data in the Lab space, and the input-side correspondence between the RGB data and each component value in the Lab space is determined. In this process, the flow shown in FIG. 5 can be used as it is to determine the data D22 that associates RGB data with Labin, so detailed description will be omitted.
      [0078]
  In the intermediate correspondence determining step S32, an intermediate correspondence (hereinafter also referred to as 4 to 6 color relations) between CMYK data (intermediate color image data) consisting of 4 colors and CMYKcm data consisting of 6 colors is referred to as a 1 to 1 relation. Decide to become. Since K is included in the CMYK data, the dark and light ink color separation conditions are determined here, and only data that falls within the ink injection amount limit is used for the CMYK cm data. In this process, the flow of S154 to S158 of FIG. 6 is used to determine data D23 defining the 4 to 6 color relationship.
  That is, using the PC, dark and light ink color separation conditions for replacing CMYK data with CMYK cm data so as to be one to one are determined (corresponding to S154). At this time, dark and light ink color separation conditions are determined such that the color measurement result acquired in the color measurement result acquiring step also has a one-to-one relationship with the CMYK data. Next, with respect to the CMYKcm data in which the light and dark ink color separation conditions are reflected, a process of limiting the ink deposition amount so as to become one to one before and after conversion is performed (corresponding to S156). Then, the CMYK data and the CMYK cm data are associated with each other to create data D23 that defines the 4 to 6 color relationship (corresponding to S158). Then, it is possible to associate CMYK data of four component colors smaller than CMYKcm data with CMYKcm data one to one, that is, if the CMYK data are different, the CMYKcm data is also different. And if the CMYK data are different, the color measurement results will also be different. Further, the associated CMYK cm data is data within a range that can be output by the printer.
      [0079]
  In the color measurement result acquiring step S33, based on 5 4 squared CMYKcm data provided with 5 density steps for each of the 4 colors of CMYK, the corresponding plurality of patches are printed by the printer, and the plurality of printed patches 21 are measured. Colorimetry is performed by the color unit 22 to acquire a colorimetric result (sample data D24) based on the Lab space. This process can be implemented using the same flow as FIG.
  That is, using the PC, data is defined that defines five fourth power grid points that are substantially equally spaced along each axis in the CMYK color space (corresponding to S202). Next, color conversion is performed on a plurality of CMYK data corresponding to lattice points into CMYK cm data (corresponding to S204). In this process, CMYKcm data corresponding to CMYK data is extracted with reference to data D23 defining the 4 to 6 color relationship, or a plurality of CMYKcm data close to the CMYK data is acquired from the data D23 and interpolation calculation is performed. It can carry out by calculating | requiring CMYKcm data by this. Further, a plurality of patches corresponding to the color-converted CMYKcm data are printed on the medium (corresponding to S206). Then, the colorimeter 22 performs color measurement on the printed patch. The PC acquires a colorimetric result based on the Lab space for all of the plurality of patches (corresponding to S208). Thereafter, the CMYK data and the colorimetric result (Lab value) are associated with each other, and sample data D24 is created in which a combination of CMYK tone values is associated with each component value of Lab space (corresponding to S210).
      [0080]
  In the second intermediate correspondence determining step S34, the second intermediate of CMY data (second intermediate color image data) consisting of the second intermediate element color CMY of three colors smaller than the intermediate element color CMYK and the CMYK data consisting of the four colors The correspondence relationship (hereinafter, also described as 3-4 color relationship) is determined to be a one-to-one relationship. Here, the K generation condition is to be determined. In this step, data D25 defining the 3-4 color relationship is determined using the flow of S152 of FIG. That is, using the PC, the K generation condition for replacing CMY data with CMYK data so as to be one to one is determined (corresponding to S152).
      [0081]
  In the use area determination step S35, the CMY-Lab relation (colorimetry result correspondence relation) between the CMY data and the colorimetry result is obtained based on the acquired colorimetry result and the determined 3-4 color relation. The use area of the CMYK cm data used by the printer is determined based on the CMY-Lab relationship. This step can be performed using the same flow as in FIG.
  First, using a PC, a plurality of colorimetric results close to CMYK data corresponding to CMY data stored in data D25 defining the 3-4 color relationship are acquired from sample data D24 (corresponding to S402). Next, an Lab value corresponding to the CMY data is determined using an interpolation operation (corresponding to S404). Then, the CMY data and the Lab value are associated with each other to create data D26 defining the CMY-Lab relationship (corresponding to S406).
      [0082]
  Thereafter, using the same flow as in FIG. 12, Labin / out are associated, and Labout and CMY data are associated. That is, information about the color gamut that can be expressed by the printer 20 is output to a display etc. using a PC (corresponding to S252), and the color gamut that can be expressed by the printer is determined from the distribution area of Lab values for CMY data. Do. Next, Labout for Labin is acquired, and data D27 that associates Labin / out is created (corresponding to S254 to S256). At that time, if colorimetry results corresponding to CMYK data are used, it is necessary to represent the color gamut that can be expressed by the printer in four dimensions, but it was made to correspond to data of CMY3 colors which is smaller than 4 colors of CMYK. By using data that defines the CMY-Lab relationship, the expressible color gamut of the printer can be expressed in three dimensions, and it becomes easy to grasp the same color gamut. In addition, if Labout is determined so as to exclude a predetermined granular appearance region where the granular appearance of K is noticeable, the image printed on the printer is less noticeable in the black granular appearance, and the image quality can be improved.
  Further, data defining a plurality of CMY-Lab relationships close to Labout stored in the data D27 is extracted from the data D26 defining the CMY-Lab relationship (corresponding to S258). Next, CMY data corresponding to the same Labout is determined using an interpolation operation (equivalent to S260). Then, Labout and CMY data are associated with each other to create data D28 (corresponding to S262).
      [0083]
  In the table preparation step S36, the correspondence relation between the RGB data and the use area of the CMYK cm data is determined based on the correspondence relation on the input side, the CMY-Lab relation, the 3-4 color relation, and the 4-6 color relation to create the LUT. . This process can be implemented using the same flow as that of FIG.
  First, using a PC, data D22 and D27 having Labin are referenced to create data that associates RGB data with Labout (corresponding to S302). Next, data corresponding to RGB / CMY data is created with reference to the same data and data D28 which associates Labout with CMY data (corresponding to S304). That is, based on the data D 28 in which the colorimetric result correspondence relationship is reflected, the correspondence relationship between the second intermediate and first color image data is determined.
      [0084]
  Furthermore, while referring to the same data and the data D25 which defines the 3-4 color relationship, data to associate RGB / CMYK data is created, and the created data and the data D23 which defines the 4-6 color relationship are referenced. The data D21 corresponding to the RGB / CMYK cm data is created (corresponding to S306). Finally, based on the data D21, a LUT of a predetermined format is created (corresponding to S308). That is, based on the correspondence between the second intermediate and first color image data, the second intermediate correspondence, and the intermediate correspondence, the correspondence between the first color image data and the use area of the second color image data is determined. To create a LUT.
  According to the above flow, the LUT can be created with a small number of colorimetry. Also, since the CMY-Lab relationship corresponding to CMY data reveals the expressible color gamut of the printer, it is possible to easily select only the area to be used from the expressible color gamut and create the LUT. It becomes possible.
  As described above, according to the present invention, a color conversion table creation method useful for creating a color conversion table, a color conversion table creation device, a color conversion table creation program, and a medium storing the program according to various aspects Can be provided.
Brief Description of the Drawings
    [Fig. 1]
  It is an explanatory view explaining an outline of a color conversion table creation method concerning a first embodiment.
    [Fig. 2]
  It is a block diagram which shows each process which comprises a color conversion table preparation method.
    [Fig. 3]
  It is a schematic block diagram which shows the computer which comprises a color conversion table preparation apparatus with a printer.
    [Fig. 4]
  It is a block diagram which shows the structure of a color conversion table preparation program typically.
    [Fig. 5]
  It is a flow chart which shows an input side correspondence determination flow.
    [Fig. 6]
  It is a flow chart which shows an intermediate correspondence determination flow.
    [Fig. 7]
  FIG. 6 is a schematic view showing an example of determining K generation conditions and dark and light ink separation conditions.
    [Fig. 8]
  It is a schematic diagram which shows the process which limits the amount of ink hit.
    [Fig. 9]
  It is a flowchart which shows a measurement result acquisition flow.
    [Fig. 10]
  FIG. 7 is a schematic view illustrating how coordinate points for printing patches in the CMY color space are set.
    [Fig. 11]
  It is a figure showing a patch printed on media.
    [Fig. 12]
  It is a flow chart which shows a use field decision flow.
    [Fig. 13]
  It is a figure which shows typically an input color gamut and an output color gamut as aL plane of Lab space.
    [Fig. 14]
  It is a flowchart which shows a table preparation flow.
    [Fig. 15]
  It is a figure explaining a mode that the data for LUT are produced.
    [Fig. 16]
  It is a block diagram which shows each process which comprises the color conversion table preparation method concerning 2nd embodiment.
    [Fig. 17]
  It is an explanatory view explaining an outline of a color conversion table creation method.
    [Fig. 18]
  It is a flow chart which shows a use field decision flow.
    [Fig. 19]
  It is a block diagram which shows each process which comprises the color conversion table preparation method concerning 3rd embodiment.
    [Fig. 20]
  It is an explanatory view explaining an outline of a color conversion table creation method.
    [Description of the code]
10: Personal computer
11: CPU
12 ... ROM
13 ... RAM
14: Hard disk
15: CD-ROM drive
16 ... flexible disk drive
17a ~ e ... interface
18a ... display
18b ... keyboard
18c ... mouse
20: Printer
21 ... patch
22 ... colorimeter
91 ... patch
R1 ... Input color gamut
R2 ... Output color gamut
R3 ... Granular appearance region
S11, S21, S31 ... Input side correspondence determination process
S12, S23, S32 ... Intermediate correspondence determination process
S13, S22, S33 ... colorimetry result acquisition process
S14, S24, S35 ... Use area determination process
S15, S25, S36 ... Table creation process
S34 ... second intermediate correspondence determination process