| 摘要 |
PROBLEM TO BE SOLVED: To increase the compression rate of lossless sub-band conversion compression. SOLUTION: A pixel correlation evaluation means 110 of a lossless optimally adaptive sub-band converter 100 calculates pixel correlation of individual pixels, which exist in the periphery of a pixel to be an object and can be referred to in order to evaluate the pixel correlation. An optimum value calculation means 120 selects, for example, a pair having maximum correlation based on the evaluation of pixel correlation to calculate an optimally adaptive processing coefficient. A sub-band conversion means 130 uses the calculated optimally adaptive processing coefficient and pixels, which can be referred to, in order to calculate a forecast value of the object pixel and performs optimally adaptive sub-band/wavelet conversion to divide a frequency component into prescribed areas on the basis of the forecast value, thus generating a sub-band/wavelet conversion encoded signal. An entropy encoding compressor 200 encodes this sub-band/wavelet conversion encoded picture signal to an entropy code and outputs it as a compressed picture signal.
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