VARIABLE QUANTIZATION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an image compression system capable of minimizing a file size while maintaining perceptive quality high for a synthetic document. SOLUTION: The image compression system of synthetic images including both texts and pictures can receive images so as not to overlap 8×8 pixel blocks and is provided with a discrete cosine transformer. The discrete cosine transformer 14 is connected to a quantizer 18 for pulling out a loss quantization factor from a quantization table 16. The loss quantization factor is corrected by a variable quantization sub system 54 based on the change of the frequency of the block, a low loss quantization factor is provided for the change of a high frequency and a high loss quantization factor is provided for the change of a low frequency. The change of the high frequency indicates the text and the change of the low frequency indicates the picture. The quantizer 18 is connected to an entropy encoder 20 and the entropy encoder 20 uses the non-loss entropy encoding factor of a Huffman table.