RGB to CMYK color transformations using combination of linear function and black printer look-up table

Abstract

This research is attempted to study the method of RGB to CMYK color transformation. There are 2 steps; the linear transformation of RGB to CMY and the transformation of CMY to CMYK through black printer LUT. It is found that the cooperation with theoretical subtractive color definition, one dimension non-linear function between opposite colors, and the linear transformation RGB to CMY is possible. The accuracy depends on the number of coefficients of the linear function. The LUT is defined by one dimension Bilinear Interpolation. The comparison of the obtained color differences, resulted from the output data CMY and CMYK, seem to be close to one another, ranging from 9 to 15. It implies that this transformation process can be used to output CMYK in stead of CMY, as the benefit is the reduction the amount of color inks and the improvement of gray balance