IMAGE FORMING APPARATUS AND COMPUTER PROGRAM PRODUCT FOR PERFORMING COLOR ADJUSTMENT BASED ON COLOR SHIFT AND TENDENCY FOR COLOR SHIFT OVER TIME

Provided is an image forming apparatus including an image forming section that periodically forms a color calibration image which is used for color adjustment along with an image on a recording material, a color information obtaining section that periodically obtains color information of the color calibration image which is formed on the recording material before color adjustment which is periodically performed, and a color adjusting section that, based on plural pieces of the color information that is obtained by the color information obtaining section, performs color adjustment on an image formed by the image forming section such that a difference between a color of an image which is supposed to be output and a color of an image which is output is reduced by a next color adjustment.