The LC82101 converts an analog image signal from a CCD or contact sensor to high-quality binary image data. The LC82101 uses an internal 8-bit A/D converter for A/D conversion, and in addition to the orthodox dithering technique, also supports an error diffusion technique that allows an even higher quality image to be acquired. These techniques apply to the whole range of processing supported by the LC82101, including full-pixel distortion correction, gamma conversion for arbitrary gamma curves, image compression processing, two-dimensional filtering, halftone processing, and image separation processing to separate documents into text, photograph, and halftone regions. Thus this LSI implements the image processing required by FAX, copier, and OCR systems.