PICTURE DATA COMPRESSOR

摘要

PURPOSE:To apply data compression with a compression factor corresponding to a picture quality requested in the unit of picture by providing a means for setting a factor round-off threshold value and a factor quantized step width corresponding to the set picture quality. CONSTITUTION:Picture data stored in a picture memory 1-14 is read in the unit of blocks for 2-dimensional discrete cosine conversion by a block data reader 1-15. The 2-dimensional discrete cosine converter 1-16 multiplies a 2-dimension discrete cosine conversion matrix and its transposition matrix from the read block data to obtain a conversion factor matrix. A picture quality selector 1-22 outputs the factor round-off threshold value 1-11 and the factor quantized step width 1-12 according to the picture quality switching signal selected by the user corresponding to the requested picture quality. A code data 1-21 formed by a coder 1-19 is added with the threshold value 1-11 and the step width 1-12 by a parameter adder 1-23 and the result is outputted as compressed data 1-13.