Three-dimensional LUTs produce a lightness signal L* from input color signals C, M and Y. The three-dimensional LUTs are respectively provided for four divisional sections of an input color signal K. A three-dimensional LUT switching device judges to what section a current value...http://www.google.de/patents/US5764795?utm_source=gb-gplus-sharePatent US5764795 - Color image processing apparatus for color matching and color matching processing method 
