Patent attributes
This invention provides an image forming apparatus capable of more reliably detecting patches formed on a recording medium while suppressing an increase in the consumption of printing media and toners. In an image forming apparatus which detects the density or color of each patch of a patch array fixed on a recording medium that is conveyed and corrects an image formation condition based on the detection result, the patches are formed as the patch array so that the conveyance-direction length of each patch gradually increases in an order of detection by the patch detection unit, and the conveyance-direction length of each patch gradually increases according to increasing of a detection position variation amount of a patch in the order of detection by the patch detection unit.