Color conversion method and apparatus with a variable gray component replacement ratio
AssigneeFuji Xerox Co., Ltd.
InventorNoriaki Seki
Life of this patent
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Abstract
An amount of a black colorant is determined from input color image signals. Then, chromaticity values, for instance, on the L*H*C* color space, of a color that is obtained by subtracting the above black amount from the input color image signals and represented by C, M and Y are determined. Finally, colorant amounts of C, M and Y are determined from the chromaticity values thus determined.
Claims3
A color conversion apparatus for converting input color signals representing an input image into amounts of a plurality of chromatic colorants and at least one achromatic colorant to reproduce the input image on an image supporting member with those colorants, said apparatus comprising:
- means for determining an amount of the achromatic colorant from the input color signals;
- means for determining chromaticity values of a color of chromatic components obtained by subtracting the determined amount of the achromatic colorant from the input color signals, including:
- means for determining a reflectance .rho.(k') of the achromatic colorant from the amount k' of the achromatic colorant;
- and
- means for determining the chromaticity values L*, H* and C* according to equations:
- L*=.rho.(k').sup.-1/3 (L*.sub.0 +16)-16
- H*=H*.sub.0
- C*=.rho.(k').sup.-1/3 C*.sub.0
- where L*.sub.0, H*.sub.0 and C*.sub.0 denote chromaticity values of the input color signals;
- and
- means for determining amounts of the chromatic colorants for representing the color of the chromatic components from the determined chromaticity values.
Dependencies are inferred from the claim text.