Device dependent color signals to/from a system should be converted into a standard color signal, such as CIELAB, for media independent color reproduction. In case of applying CIELAB to the standard color signals, the relationship between CMYK and L*a*b* is complicated in contrast to NTSC RGB and YIQ or others. This paper presents a transformation from L*a*b* to printer density by the Prism Interpolation) and Slant Prism Interpolation) have been developed to realize a flexible and high-speed color conversion.