摘要 |
An image compression system and method for compressing image data for transmission. Each block and corresponding sub-blocks of pixel data is subjected to a discrete cosine transform (DCT) operation (10, 12). Varying levels of sub-blocks (QC16, QC8, QC4, QC2) of resulting corresponding transform coefficients 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 the composite block is determined by a comparison process between transform block and sub-block coding efficiency (20, 26, 32). The composite block is variable length coded (56) to further reduce bit count in the compressed data. |