| 摘要 |
PROBLEM TO BE SOLVED: To efficiently compress/expand a synthetic digital image while integrating lossless and loss compression by optimizing subband decomposition, continuous approximation, encoding and a bit stream operation. SOLUTION: A compressor 110 compresses an uncompressed image 105, produces a bit stream 115 in a scalable way and produces an expanded image 135 from the bit stream that applies a prescribed number scaling operation 120 by an expander 130. The bit stream operation selects the number of quantization layers which should be included in each subband. Continuous approximation and an encoding element produce plural layers of quantized subband symbols which are encoded by using context adaptive arithmetic coding, decide an encoding context based on an adjacent sample of a sample within the range of the same subband together with a quantizer that should be used for an optional specific subband sample and design in such a manner that information is concentrated on the neighborhood of an area where activity is high. The subband and the quantization layer are encoded at the same time. |
