Color conversion apparatus, color conversion method, color change program and recording medium

Abstract

There is provided a color conversion table having a plurality of pieces of reference color image data making correspondence between color data for a first image device and color data for a second image device and including a specified total information amount. The color conversion table is used to distribute the reference color image data over a prescribed area in a specified color space. Color data information for each reference color image data is increased more than a specified amount within a limit of the specified total information amount. Further, a color conversion table is created using an original table which highly accurately defines colors in part of the table. If such color conversion tables are referenced for color conversion, it is possible to suppress the storage capacity, provide color matching, and perform high accuracy color conversion.

1 . A color conversion table data which defines correspondence between first color image data used for a first image device and second color image data used for a second image device and is referenced when the first color image data is converted into the second color image data,
 wherein a color space contains a limited area for making correspondence between the first color image data and the second color image data and the correspondence accuracy is improved within the area.   
     
     
         2 . A color conversion table data which is referenced during conversion from first color image data used for a first image device into second color image data used for a second image device, comprises a plurality of pieces of reference color image data maintaining correspondence between color data for the first image device and color data for the second image device, and has a specified total information amount,
 wherein the reference color image data is distributed over a prescribed area in a specified color space to increase color data information about each reference color image data over a specified amount within a limit of the specified total information amount.   
     
     
         3 . A medium recording a color conversion table creation program to create a color conversion table which defines correspondence between first color image data used for a first image device and second color image data used for a second image device with respect to a plurality of reference points,
 wherein the program allows a computer to implement:   an original table storage function which stores an original table having part of information in a color conversion table to be created; and   a color conversion table generation function which can generate the color conversion table by combining at least two original tables defining different color accuracies and by supplementing information missing from the plurality of reference points.   
     
     
         4 . The medium recording a color conversion table creation program according to  claim 3 , wherein the original table storage function stores at least two original tables having different gradations for color image data. 
     
     
         5 . The medium recording a color conversion table creation program according to  claim 3 , wherein the original table storage function stores at least two original tables having different reference point densities for defining correspondence. 
     
     
         6 . The medium recording a color conversion table creation program according to  claim 5 , wherein one of the original tables has a higher reference point density than a reference point density in the other original table and has a lower reference point density than a reference point density in the color conversion table. 
     
     
         7 . The medium recording a color conversion table creation program according to  claim 3 , wherein the second image device is a printing apparatus capable of using a plurality of colors of ink; and wherein the original table storage function expresses a gradation change of a specified color component in the second color image data by identifying a color component using a smaller number of inks than the other color components and, for this color component, storing an original table having a higher accuracy than for the other color components. 
     
     
         8 . The medium recording a color conversion table creation program according to  claim 3 , wherein the color component using a smaller number of inks than the other color components is yellow. 
     
     
         9 . The medium recording a color conversion table creation program according to  claim 3 , wherein the second image device is a printing apparatus capable of using a plurality of colors of ink; and wherein the original table storage function identifies a color component having a wider range of displayable brightness than the other color components and stores an original table having a higher accuracy than the other color components. 
     
     
         10 . The medium recording a color conversion table creation program according to  claim 3 , wherein a high brightness color in one of the original tables is given a higher accuracy than an accuracy for defining colors in the other original table. 
     
     
         11 . The medium recording a color conversion table creation program according to  claim 3 , wherein a low brightness color in one of the original tables is given a higher accuracy than an accuracy for defining colors in the other original table. 
     
     
         12 . The medium recording a color conversion table creation program according to  claim 3 , wherein a low saturation color in one of the original tables is given a higher accuracy than an accuracy for defining colors in the other original table. 
     
     
         13 . The medium recording a color conversion table creation program according to  claim 3 , wherein any of or a combination of a flesh color and its peripheral colors, a blue color and its peripheral colors, and a red color and its peripheral colors in one of the original tables is given a higher accuracy than an accuracy for defining colors in the other original table. 
     
     
         14 . The medium recording a color conversion table creation program according to  claim 3 , wherein the color conversion table generation function allows a user to select whether or not to generate a color conversion table by means of the combination. 
     
     
         15 . The medium recording a color conversion table creation program according to  claim 14 , wherein the selection enables generation of a color conversion table using at least two original tables having different gradations for the color image data, generation of a color conversion table using at least two original tables having different reference point densities for defining the correspondence, and generation of a color conversion table using both of these conditions. 
     
     
         16 . The medium recording a color conversion table creation program according to  claim 3 , wherein there are provided an image data acquisition function to obtain image data comprising the first color image data and a specific color ratio computation function to compute a ratio of a specific color to the obtained image data as a whole; and wherein the color conversion table generation function, when a ratio computed by the specific color ratio computation function exceeds a specified threshold value, generates a color conversion table according to the selection using an original table which highly accurately defines colors including the specific color. 
     
     
         17 . A color conversion table creation method of creating a color conversion table to define correspondence between first color image data used for a first image device and second color image data used for a second image device with respect to a plurality of reference points by using an original table which is stored in a specified storage capacity and has some information about a color conversion table to be created, the method comprising:
 generating the color conversion table by combining at least two original tables defining different color accuracies and by supplementing information missing from the plurality of reference points.   
     
     
         18 . A partial color conversion table to be referenced to create a color conversion table which defines correspondence between first color image data used for a first image device and second color image data used for a second image device with respect to a plurality of reference points,
 wherein the partial color conversion table is to be combined with an original table defining color image data for a plurality of reference points according to the specified number of gradations during creation of a color conversion table and defines some colors in the color conversion table to be created using more gradations than the specified number of gradations.   
     
     
         19 . A partial color conversion table to be referenced to create a color conversion table which defines correspondence between first color image data used for a first image device and second color image data used for a second image device with respect to a plurality of reference points,
 wherein the partial color conversion table is to be combined with an original table defining color image data according to a specified reference point density during creation of a color conversion table and defines some colors in the color conversion table to be created using a higher reference point density than the specified reference point density.