rgb2map

Convert RGB colors to indexed colormap colors.
rgb2map converts an RGB image or colormap to an indexed color image or colormap using color differences. rgb2map calculates the color difference between each RGB pixel in an input image and every RGB triplet in the input colormap by calculating ΔE in the CIE L*a*b* color space (CIE 1976 standard). The min function is used to find the index of the minimum ΔE (if more than one minimum value exists, the index of the first is returned). The function is an alternative to Matlab's rgb2ind.