Patent ID: 6377366
Filing Date: 2002-04-23
Classification: H04N

Abstract:
A color reproduction data conversion method to convert three-dimensional colorimetric data into four-dimensional color reproduction data containing color components of cyan (C), magenta (M), yellow (Y), and black (K), while maintaining a metamerism, comprising:performing an inverse conversion from a three-dimensional calorimetric space to a three-dimensional CMY color space for a plurality of different K plate amounts in order to obtain as color matching ink amounts, those ink amounts of CMY colors being metamer with the three-dimensional calorimetric data and setting a reference K plate amount with respect to the plurality of K plate amounts; obtaining a ratio between the total ink amount of CMYK for each K plate amount and the total ink amount of CMYK in the case of the reference K plate amount as an achromatic amount of the K plate; obtaining an achromatic amount function for said amount of the K plate in a linear portion by examining a portion in which said achromatic amount becomes non-linear for the K plate amount; generating a mapping function from the three-dimensional colorimetric data and the achromatic amount to the ink amounts of CMYK in the linear portion and obtaining a K plate control condition to be used as a weighting coefficient for reflecting the K plate control condition to the achromatic amount successively in order to perform a weighting to the achromatic amount with said K plate control condition previously selected; determining the achromatic amount from the achromatic amount function and the selected K plate control condition as a restraint condition for the inverse conversion from three-dimensional calorimetric data to four-dimensional color reproduction data; calculating ink amounts of CMYK from the thus determined achromatic amount and the three-dimensional colorimetric data with the use of said mapping function; and printing an image based on the calculated ink amounts.