Image processor, control method therefor, image forming apparatus, and program

摘要

An image processor capable of detecting whether an image formed on a recording medium by the image forming apparatus is defective or non-defective with as high accuracy as possible and at high speed. A sheet-surface portion-determining section determines sheet-surface portions of a non-defective formed image on a pixel basis, and stores data of the sheet-surface portion/non-sheet-surface portion distribution, and extracts smallest RGB pixel values from image data of a group of pixels determined to correspond to a sheet-surface portion, to form RGB offset signals based on the smallest values. A sheet-surface portion determination-based offset section subtracts the values of the offset signals from the image data (RGB) of an inspection object. An image quality-determining section determines whether a formed image on the object is defective or non-defective on a pixel basis, using the most significant 1-bit RGB values subjected to the subtraction and the distribution data.