To provide an apparatus and a method for generating an anti-aliasing effect in a saturated state text in addition to a non-saturated state text, reducing an effect of an input moire caused by a scanner and maintaining a long term stability of electrophotographic process of a color.

The apparatus for processing gray level image data comprises first and second halftone screen processing units 18 and 20, a unit for analyzing a pixel of each of inputs of the processing units and contrast indexes, a unit for responding to the contrast index to generate a blending coefficient, an input of the blending arithmetic processor 24, a gray level image enhancement processing unit 28, a detector 28 and a selector 32.