| 摘要 |
<p>On the image compressing side, the lossless wavelet conversion factors subjected to lossless wavelet conversion are quantized with a coarse step size and entropy-coded, and then the quantization error signals are quantized with fine step size and entropy-decoded in order, thereby generating a progressively coded bit stream. On the image expanding side, for each coded bit stream perform corresponding stage of image progressive reproduction and display, and the lossless wavelet conversion factors generated by entropy-decoding and reverse-quantization are subjected to lossless wavelet conversion, the image data produced by the reverse conversion are added to already reproduced image data together with image update auxiliary information, thereby reproducing and displaying images progressively. Since the auxiliary information required to update the image is generated from part of the information on the lossless wavelet conversion factors required at the time of updating the quality of the image by one grade and part of the lossless wavelet conversion factors required to generate an already displayed image, it is unnecessary to hold all information on the lossless wavelet conversion factors required to generate the image before the update and the memory capacity can be reduced. <IMAGE></p> |
