The CIELab system of color coordinates is not optimal for use in desktop publishing (DTP) systems, because it is non-uniform, not well matched to human visual dynamics, and computationally inconvenient. CIELab uses cube roots of differences of color matching functions. In complex scenes, perceived lightness varies quadratically, not cubically, with intensity. Chroma varies in a more complex way but is also not well represented by cubic polynomials. As a result, CIELab exaggerates highlights and compresses shadows. It distorts the concentric circles and radii of the Munsell chart into ellipses and curves. This makes it difficult to achieve appearance equivalence during gamut compression. Gamut compression is an essential element in working with the variety of inexpensive DTP devices. Users expect DTP operations to proceed rapidly on inexpensive equipment. This dictates heavy reliance on integer arithmetic and lookup tables. These techniques do not mesh well with the computational complexities of CIELab.