IMAGE FORMING APPARATUS AND CORRECTION EFFECT VERIFICATION METHOD IN IMAGE FORMATION

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of detecting an image on recording paper while suppressing a cost increase and a machine-size enlargement caused by an increase in the number of sensors and capable of forming a test pattern for correction and a test pattern for verifying the effect without any waste of the recording paper for appropriately acquiring an image detection effect on the recording paper.SOLUTION: The image forming apparatus is configured to: detect a test pattern formed on the surface of recording paper 20 by an output image detection sensor 31 disposed near the downstream side of a fixing unit 25; adjust and correct image forming conditions based on the detection result of the detector; convey the recording paper 20 the surface of which the test pattern is formed on, to a duplex conveyance path 28 so as to make it into a re-feedable state; re-feed the recording paper 20 after the correcting the image forming conditions and form a test pattern for verifying correction effect on a backside; and detect the test pattern for verifying correction effect again by the output image detection sensor 31, thereby verifying the correction effect.