| 摘要 |
An adaptive block size image compression method and system for compressing image data, a respective method and sys- tem for further compressing the image data for transmission. Each block and corresponding sub-blocks of pixel data is subjected to a discrete cosine transform (DCT) operation (10a-10d). Varying levels of sub-blocks of resulting corresponding transform coef ficients (12a-12d) are selected for construction into a composite transform coefficient block (QC) corresponding to each input block of pixel data. The selection of transform coefficient block size for t he composite block is determined by a comparison pro- cess (20, 26, 32) between transform block and sub-block coding efficiency. T he composite block is variable length coded to further reduce bit count in the compressed data. A discrete quadtree transform (DQT) operation is in supplement of the adaptive block size block selection with coefficient replacement to optimize image data compression.
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