| 摘要 |
An image data encoding apparatus includes a wavelet transform unit which produces a first subband coefficient and a second subband coefficient as an output in response to each of blocks of the input image data, the first and second subband coefficients being produced by performing a multiple decomposition process in which only the first subband coefficient is further decomposed. A first text transform unit produces an intensity coefficient of a first kind as well as a set of coefficients of a second kind as an output in response to each block, the intensity coefficient including significant bits, and only the intensity coefficient being further decomposed in the first text transform unit. A second text transform unit produces a set of coefficients of the second kind as an output in response to each block, one of the coefficients of the second kind including significant bits but not being further decomposed. A selector selects one of the output of the wavelet transform unit, the output of the first text transform unit and the output of the second text transform unit, as an input to an entropy coder, in accordance with a combination of an area-discriminating signal and a text-transform control signal.
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