1. An image forming apparatus comprising: an image formation portion configured to form an image on an image carrier; a measuring portion configured to measure image formation ability associated with resolution of the image formation portion; and a determination portion configured to determine an operating condition of the image formation portion according to a measured image formation ability and size of a component image constituting a code pattern image to be formed by the image formation portion, wherein the code pattern image is constituted by a combination of a plurality of the component image having a predetermined shape wherein the code pattern image is a pattern image corresponding to a code information.