| 摘要 |
PURPOSE: To attain the target compressibility through a single compression processing by quantizing the block image data which underwent the discrete cosine transformation(DCT) based on the quantization tables that satisfy the necessary conditions and applying the entropy coding to the transformation coefficients to compress them. CONSTITUTION: The multilevel image data are divided at a block division part 1, undergo the DCT through a DCT part 2, and are quantized at a quantization part 3 based on plural quantization tables 4. The DCT coefficients are compressed at an entropy coding part 7 and outputted. At the same time, the quantity of compressed data measured at a compressed data quantity measurement part 9 is compared with the target compressed data quantity of a target compressed data quantity storage device 10 to select one of those corresponding tables 4 at a comparison processing part 11. Thus the target compressibility is attained by a single compression processing not by two operations carried out for every block. |
