An image of stabilized tint is output even if a supplied transfer medium is changed to a transfer medium of a different surface gloss or type of paper. If the supplied transfer medium has changed, the tint of a corrective image formed on the transfer medium is sensed, a tint correction of an image forming portion is performed based upon result of sensing, and corrective data of the tint correction and information relating to the transfer medium is stored. If a change of the transfer medium is sensed subsequently, a determination is made as to whether the transfer medium is substantially the same transfer medium, based upon the stored information relating to the transfer medium. If the transfer medium is substantially the same, then image processing is executed based upon the stored corrective data.