Image formation device and image processing device

Abstract

The invention provides an image formation device based on the electrophotographic system, whereby, when an outputted image varies from the halftone area to the background area in the sub-scanning direction, the density reduction of a rear end area of the halftone area that borders on the background area can be prevented, by means of simplified and small-scale processing. In this image formation device, a backward edge of the halftone area that borders on the background area is extracted, and an image data value of the background area including m pixels after this backward edge in the sub-scanning direction, of input image data Si, is modified to a setting value with correction data. The setting value is set to a value slightly lower than the threshold value corresponding to the dot area coverage of an image recurrence start point. If there is a halftone area whose image data value given by input image data Sib is greater than the threshold value, or a background area whose image data value is greater than the setting value, in an area including m pixels in the sub-scanning direction after the backward edge of the halftone area given by input image data Sia, the value of the image data with regard to that area will not be modified, and only the value of the image data with regard to the area from the backward edge of the halftone area to that area will be modified to the setting value.