| 摘要 |
<p>PURPOSE:To perform compression of a high compression rate on a large quantity of picture data in a short time by selecting the optimum bit assigning pattern against an orthogonally converted picture data array and performing block encoding against block data which cannot be compressed well by the orthogonal conversion. CONSTITUTION:Orthogonally converted Data AD(i, j) are transferred to a bit assigning pattern selection circuit 6 and the optimum pit assigning pattern to the data AD(i, j) is selected. Weighting overflow values outputted from a weighting circuit 12-k are supplied to an overflow counter 13-k and summed. The summed value is discriminated whether or not it is within ranges of appropriate thresholds TH1 and TH2 by a comparator circuit 14-k. When the summed value is within the above-mentioned ranges, a signal CPk indicating that the data compression by using the said bit assigning pattern is adequate is supplied to a bit assigning pattern selector 17. When the encoding by means of orthogonal conversion is inappropriate, such block data ID' (i, j) are compressed by a block encoding method.</p> |
