IMAGE FORMING APPARATUS

A differential correction data generating unit measures two density characteristics at a reference linear velocity and another linear velocity from scanned images of two test charts printed at the reference linear velocity and the another linear velocity, and generates differential correction data as a difference between correction amounts for the measured two density characteristics. A correction amount adjusting unit measures a density characteristic at the reference linear velocity from an adjustment toner pattern formed on an intermediate transfer member, and thereby adjusts a correction amount for the density characteristic at the reference linear velocity. A density characteristic of a printing image is corrected, (a) for the reference linear velocity, on the basis of the correction amount at the reference linear velocity, and (b) for the another linear velocity, on the basis of the correction amount at the reference linear velocity and the differential correction data.