Patent ID: 6026180
Filing Date: 2000-02-15
Classification: H04N

Abstract:
A method for performing phased compression of color images comprised of a plurality of sequenced frames, comprising the steps of:performing color compression on a sequence of color images to generate a color quantizer and a sequence of indexed color images;performing temporal compression on said sequence of color images to generate a tile mask; andperforming spatial compression on said sequence of color images to generate a tile table and a plurality of indexed tile images;wherein said step of performing color compression comprises the steps of:forming a color histogram from samples of color pixels in said sequence of color source images;generating said color quantizer by partitioning a color space based on said color histogram, said step of generating said color quantizer comprises the step of determining a set of color centroids to represent said color pixels; andquantizing said color pixels using said color quantizer;wherein said step of determining a set of color centroids comprises the steps of:determining in said color space a distance metric between each respective sample in said histogram and a plurality of current centroids, said plurality of current centroids residing in an immediate neighborhood of a Voronoi region of a centroid to which the respective sample was assigned in a prior iteration;assigning each sample in said histogram to a closest current centroid; andadjusting said current centroids based on an accumulation of deviations between each current centroid and a plurality of respectively assigned samples.