| 摘要 |
<p>An image signal encoding method by orthogonal transformation comprises the steps of conducting orthogonal transformation on each block of two-dimensional image signals based on a predetermined orthogonal function, and encoding the signals, which are obtained by transformation and arrayed in the order of sequency of the orthogonal function in the block, with an intrinsic code length. Code length allocation suitable for a block adjacent to the block, which has already been subjected to encoding, is predicted based on encoded signals and code length allocation in the block already subjected to encoding, and the transformed signals in the adjacent block are encoded in accordance with the predicted code length allocation. Or, transformed signals on the same sequency are extracted from the blocks, a standard deviation of the transformed signals thus extracted or a mean value of absolute values thereof is calculated for each of different sequency, and the code length for the transformed signal of each sequency is adjusted based on the standard deviation or the mean value.</p> |
