IMAGE SIGNAL PROCESSING UNIT AND ITS METHOD

摘要

PROBLEM TO BE SOLVED: To reduce image deterioration caused by rounding of arithmetic operations conducted in a quantization means as much as possible and to attain high compression processing. SOLUTION: This method employs; a division means 103 that divides a received image signal into a plurality of blocks consisting of a prescribed number of pixels; a transformation means 104 that applies orthogonal transformation to image data of each block division by the division means 103; a quantization means 106 that quantizes the image data orthogonally transformed by the transformation means 104; a coding means 107 that applies variable length coding to the quantized image data; and a means that adjusts the code after quantization and variable length coding to have a code in a range consisting of a prescribed number of blocks. Then the method for rounding an arithmetic operation of the quantization means 106 is selected based on the received data and a quantization characteristic of the quantization means 106 in order to conduct image compression with less image quality deterioration and to reduce a maximum value of a quantization error.