An image forming apparatus which having a plurality of image processing modes, that is capable of accurate density gradation control without performing output of any patch image to a recording medium in all the image processing modes. A first correction parameter corresponding to a first image processing mode is prepared on the basis of a result of detection, by a second density detection unit, of the image formed on a recording medium in a first image processing mode. A second correction parameter corresponding to a second image processing mode is prepared on the basis of the first correction parameter and a correlation, stored in a storage unit in advance, between density of a toner image formed on an image bearing member in the first image processing mode and density of toner image formed on the image bearing member in the second image processing mode.