To provide an image processor capable of stably forming a half-tone image with high definition and to provide an image forming apparatus, an image processing method, a image processing program, and a recording medium with the same recorded.

A pixel discrimination section 71 acquires the density of a target pixel and surrounding pixels, reads a pixel pattern from a pattern storage section 7 and determines whether or not the target pixel is to be a processing object by a data correction section 17. When the pixel determination section 71 determines that the target pixel is a pixel to be the processing object by the data correction section 17, the pixel determination section 71 outputs the determination result and information of the pixel pattern for the target pixel and the surrounding pixels to a pixel conversion section 74 and a correction value storage section 73. The pixel conversion section 74 reads a concerned correction value from the correction value storage section 73 on the basis of the information and the determination result received from the pixel determination section 71 and attaches the correction value to the density value of the surrounding pixels. A print section 22 forms an image on recording paper on the basis of the image data after the correction.