| 摘要 |
PURPOSE:To constitute efficient arithmetical codes by estimating symbol appearance probability with high accuracy when a dither binary image symbol depends on the symbol appearance probability. CONSTITUTION:When it is judged a code length is extended corresponding to the appearance probability of a binary symbol, a dither threshold value is adjusted by a dither threshold value adjusting part 20. Based on this adjusted dither threshold value, the symbol is corrected to a binarized symbol suitable for data compression using the arithmetical codes by a dither binarizing processing part 10. Since the symbol appearance probability suitable for the corrected symbol is estimated by a symbol appearance probability estimation part 21, the binary image can be encoded with high compressibility, and efficient arithmetical codes can be constituted. |
