Patent ID: 6542631
Filing Date: 2003-04-01
Classification: G06T,G09G,H04N

Abstract:
A color image encoding method which inputs and encodes color image data, comprising the steps of:counting the number of colors used in the input color image data; creating a global palette in which indexes corresponding to respective colors are listed when the number of colors used is a predetermined value or less; dividing the input color image data into a plurality of blocks; creating a local palette in which the indexes in the global palette are listed when the number of colors in a block is less than the number of colors in the global palette; assigning the indexes in the global palette to the input pixels when the number of colors in the block is the same as the number of colors in the global palette and which otherwise assigns the indexes in the local palette to the input pixels; and encoding the color indexes, wherein, when the predetermined value is 2n (n is 2x when x is an integer equal to or greater than 0), the indexes in the global palette are expressed by n bits, and when the number of colors in the block is 2m (m is 2x where x is an integer equal to or greater than 0), the index in the local palette is expressed by m bits, and wherein the local palette is not created when n=m, and the local palette is created when n>m.