| 摘要 |
Blocking means subjects pixel information of an original sample surface to blocking, a DCT circuit transforms the blocks of input data, a quantizer quantizes the DCT-treated data, a VLC circuit subjects the quantized data to variable-length coding, and a measuring circuit measures the code length based on the quantized data. Variable-length coded data or input sample data is selected in accordance with an output from the measuring circuit so that when the variable-length code content after entropy coding is greater than the data content of unit input sample surface, the input sample data itself, instead of the variable-length coded data, may used as data to be compressed, whereby the average code content is reduced.
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