Patent US 4,477,833

An apparatus for converting a color image from one color space to another color space includes a memory in which is stored a finite number of output signals which represent colors in the output space and which is addressed by signals representing a color in the input space. In order to derive an output color value for an input color located between colors stored in the memory, an interpolation process is utilized. The interpolation process takes into account the four closest color values in the memory above and below the input color and develops an interpolated output color value from vectors derived from the four color values.