PURPOSE: To improve a gradation reproducibility by a method wherein adjacent dots are overlapped in a character area to maintain the continuity of a line, and adjacent dots are prevented from being overlapped in a pseudo halftone area.

CONSTITUTION: For example, when an image is outputted in a dot matrix form, an input means 100 inputs image data containing a character part and a pseudo halftone part. In a next image processing part 101, an image separation circuit 1 separates the image data inputted from the input means 100 into a simple binarizing area corresponding to the character part and a pseudo halftone area corresponding to the pseudo halftone part. A pulse width adjusting circuit 2 adjusts image data 4 in the simple binarizing area separated by the image area separation circuit 1 so that adjacent dots can be overlapped with each other. A pulse width adjusting circuit 3 adjusts image data 5 in the pseudo halftone area separated by the image area separation means 1 so that adjacent dots can be separated from each other. An OR gate 7 synthetically outputs results 8, 9 of the pulse width adjusting circuits 2, 3.