CONTINUOUS GRADATION COMPRESSION DEVICE AND METHOD, CONTINUOUS GRADATION EXPANSION DEVICE AND METHOD, DATA PROCESSOR AND DEVICE AND MEMORY MEDIUM IN WHICH PROGRAMS FOR EXECUTING THE PROGRAMS

摘要

An image processor by which an excellent image can be obtained even after compression and expansion. A compression circuit (12) has a line scanning unit (22) which divides original image data into color data groups in relation to respective pixels, a line compression unit (24) which expresses the value (y) of the color data corresponding to each pixel position in a predetermined section with a polynominal: y = ax<3> + bx<2> + cx + d wherein (x) denotes the pixel position which is a variable and a parameter calculation unit (26) which obtains the parameters of the polynominal. An expansion circuit (14) has a line expansion unit (34) which obtains the color data values corresponding to the respective pixel positions in accordance with the received parameters and pixel positions. The restored image data are outputted to a display device, etc.