To provide an image processing method, etc., by which a halftone image can be reproduced well even when the tone reproducing characteristic of an electrophotography device changes due to the history, etc., of a photoreceptor, the device, etc., without deteriorating the graininess of the image nor lowering the resolution of the image due to the periodic structure of a screen.

In the image processing method, output image signals are generated by comparing inputted image signals with a threshold matrix prestoring thresholds used for deciding whether or not the picture elements in a screen cell composed of a plurality of picture elements of a dot screen are to be recorded, and the image signals are outputted to an image forming device having a nonlinear region in part of its image signal-output density characteristic. The image forming device is constituted to generate the output image signals by using a threshold matrix in which nonrecorded isolated picture elements which are not recorded by means of the image forming device are arranged, when picture elements are isolated between thresholds having largely inclined image signal-output density characteristics.