| 摘要 |
PROBLEM TO BE SOLVED: To allow a color transformation device to transform colors at a high speed with high precision regardless of a small memory capacity. SOLUTION: In a color space which is separated into lightness components and other components than the lightness components such as a CIEL*a*b* color space, a change in an output color with respect to a lightness component of an input color is smaller and smoother than a change in the output color with respect to other components of the input color than the lightness component in a relation between the color space and an optical color space after transformation. A coefficient (e) of an n-dimensional polynomial calculating a CMYK from an L* as to combinations of all values of a*, b* is obtained and stored in a coefficient storage means 2 by utilizing the principle above. The coefficient (e) is read from the coefficient storage means 2 based on the a*, b* in the input color L*axb* and a polynomial arithmetic means 3 uses the coefficient (e) to calculate the n-th degree polynomial from the L* in the input color L*a*b* and to calculate an output color CMYK. Only coefficients as to sets of discrete values of the a*, b* are stored in the coefficient storage means 2 and coefficients of the other sets of the values of the a*, b* can be obtained through interpolation based on the discrete coefficients.
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