The LC82103 converts the analog video signal from the CCD contact image sensor into high-precision binary image data. The LC82103 includes an 8-bit A/D converter and two 6-bit D/A converters. The 6-bit D/A converters are used for setting reference potential (high and low) of the 8-bit A/D converter. The LC82103 converts the input analog data to high precision multilevel data, that is produced by all pixel shading correction process, multilevel image resolution converting process, and correction process of user defined curves. That multilevel data is converted to high-precision bi-level image that is produced by using two dimensional filtering, a image separation method, and an error diffusion technique. Finally the LC82103 is able to reduce the image in the horizontal and vertical directions, too. The LC82103 requires absolutely no external memory since it limits the number of pixels processed to 3072/line. This LSI can implement the image processing used by FAX, copier, and OCR applications.