| 摘要 |
A decoder is used in an end-to-end scalable video delivery system operable over heterogeneous networks. The decoder may software-based and computationally low complexity, or may be implemented inexpensively in ROM hardware. The system utilizes a scalable video compression algorithm based on a Laplacian pyramid decomposition to generate an embedded information stream. At the receiving end, the decoder extracts from the embedded stream different streams at different spatial and temporal resolutions. Decoding a 160x120 pixel image involves only decompressing a base layer 160x120 pixel image. Decoding a 320x240 pixel image involves decompressing and up-sampling (e.g., interpolating) the base layer to yield a 320x240 pixel image to which is added error data in a first enhancement layer following its decompression. To obtain a 640x480 pixel image, the decoder up-samples the up-sampled 320x240 pixel image, to which is added error data in a second enhancement layer, following its decompression. Because decoding requires only additions and look-ups from a table stored in a small (12 Kb) memory, decoding occurs in real-time. Subjective quality of the compressed images preferably is enhanced using perceptual distortion measures. The system also provides joint-source channel coding capability on heterogenous networks. The look-up table or codebook includes the inverse perceptual weighting (preprocessed) and the inverse transform (preprocessed). Decoding permits the codewords within the look-up table codebook to include preprocessed color conversion, dithering, color palletization, edge-enhancement, decimation, and interpolation. <IMAGE> |
