Patent ID: 7952757

Claim:
An apparatus for performing color conversion by referring to a profile defining correspondence relationship between colorimetric values and ink amount data, comprising: a profile memory that stores a plurality of profiles; and a color converter that selects one profile from among the plurality of profiles and converts given colorimetric values into ink amount data by referring to the selected profile, wherein each profile is produced using a plurality of sample ink amount data selected based on evaluation indices including a color difference index and an image quality index, the color difference index represents a color difference between a sample color calculated from a spectral reflectance of a virtual sample patch that has to be printed with an ink amount represented by the sample ink amount data and a comparative color selected as a basis for comparison, at least one of the image quality indices is a graininess index obtained by applying the sample ink amount data to a neural network prepared based on a plurality of correspondence relationships between ink amount data for graininess evaluation and sample graininess indices obtained by actually evaluating a patch for graininess evaluation that is actually printed with the ink amount represented by the ink amount data for graininess evaluation, the neural network being prepared by taking a plurality of correspondence relationships between the ink amount data for graininess evaluation and the sample graininess indices, the ink amount data for the graininess evaluation includes at least two kinds of ink amount data sets, one ink amount data set reproducing a patch for the graininess evaluation, the patch providing a uniform gradation for at least a primary color in an ink amount space, and another ink amount data set being distributed in the entire ink amount space, a number of the another ink amount data set being selected so that a number of a colorimetric value of the patch for the graininess evaluation belonging to each brightness region corresponds to a cross-sectional surface area for each brightness of a printer gamut of a printer that prints using the selected profile, and the ink amount data for the graininess evaluation includes an ink amount data set selected from a gray region within a constant chroma C* =5 with a gray axis as a center and an ink amount data set in a vicinity of skin color and sky blue color.