APPARATUS FOR BINARIZING IMAGES

The invention provides an image binarizing apparatus which includes multi-value image window circuitry for retrieving multi-value image data; a first binarizing circuit for binarizing the multi-value image data in accordance with a variable threshold determined based on the multi-value image data of pixels around a desired pixel; a second binarizing circuit for binarizing the multi-value image data in accordance with a predetermined threshold; and binary image window circuitry for retrieving image data which has been binarized by the second binarizing circuit. The image binarizing apparatus further includes edge detecting circuitry for comparing and collating binary two-dimensional image data obtained by the binary image window circuitry with edge templates each having a predetermined angle; memory circuitry for storing two types of smoothly binarized data in addresses which are generated based not only on the multi-value image data obtained by the multi-value image window circuitry, but also on the edge detection data which is output from the edge detecting circuitry; and selecting circuitry for selecting either one of the two types of smooth binary image data which are output either from the first binarizing circuit or from the memory circuitry.