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A fast algorithm for inverse color map computation

Luc Brun &
Claude Secroun.
The inverse colormap operation is the process
which allows an image to be displayed with a
limited set of colors. In order to obtain minimal
visual distortion between the input image and the
displayed image, inverse colormap algorithms
associate each color with its nearest
representative. The method presented in this paper
is based on a Karhunen-Loeve transformation,
which allows us to efficiently approximate the 3D
Voronoi diagram implicitly used by inverse color
map algorithms by its 2D projection into the plane
defined by the first two eigenvectors of the
covariance matrix and then performing an
additional correction step. The complexity of our
algorithm is independent of the size of the
colormap. Moreover, its results are equal or quite
close to the optimal solution.