Image-region discriminating method and image-processing apparatus

Abstract

A degree of frequency and a comparison difference value are used as an amount of feature that is to be inputted to a discrimination circuit so as to discriminate the kind of regions. The degree of frequency is represented by the smaller of two sums, that is, the sum of absolute values of the density-level difference between pixels adjoining in the line direction of the pixels within the specific region and the sum of absolute values of the density-level difference between pixels adjoining in the direction orthogonal to the line of the pixels, which is obtained by a frequency-degree extracting circuit. Further, the comparison difference value is represented by the comparison difference between a maximum value and a minimum value in the density levels of all pixels within the specified region, which is obtained by the comparison difference circuit. Among a plurality of preset filters, one of the preset filters is selected based upon the amount of feature, and a filtering process is carried out by a filtering-process circuit by using the filter. With this arrangement, discrimination is made as to the kind of region, and a proper filtering process is carried out depending on which region, among the character region, photograph region and halftone-dot region, each focused pixel in an image that has been read belongs to.