| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital array re-indexing method and a digital data compressor capable of compressing efficiently a palletized image. SOLUTION: In this method and compressor, a pallet-indexed image is re- indexed by using an array of a symbol cross count which displays the frequencies in occurrence of one or more determined context relations in the image, for example, one or more symbols adjacent to each other. The pallet index is operated so as to assign an index as near as possible to the symbol adjacent to it in the symbol space, then the compression characteristics of the image caused by many no-loss compressors is enhanced. In the above method, a pool 102 of one dimensional re-assignment and a seeded symbol assigned to a seeded position 104 are in usage, and according to a potential function using a cross count array, one symbol is selected to locate a position at right or left, position in the pool 102. By the repetition of this process, while the next choice, a first and a second pool symbol are analyzed, and the symbol is input into the pool 102 so as to minimize the average difference of pixels in the re-indexed image. |
