1. An image forming apparatus comprising: an image formation unit including a photosensitive member, a charging unit configured to charge the photosensitive member, an exposure unit configured to expose the photosensitive member charged by the charging unit to form an electrostatic latent image, a developing unit configured to develop the electrostatic latent image to form an image on the photosensitive member, and a transferring unit configured to transfer the image from the photosensitive member to a printing medium; a control unit configured to cause the image formation unit to form a pattern image including a first dot and a second dot of an area that is larger than that of the first dot; an obtaining unit configured to detect the pattern image and obtain first graininess information indicating graininess of the first dot and second graininess information indicating graininess of the second dot; a predicting unit configured to predict third graininess information regarding the second dot based on the first graininess information obtained by the obtaining unit; a selection unit configured to select an image forming condition to be corrected among charging conditions of the charging unit, developing conditions of the developing unit, and transfer conditions of the transferring unit, based on the first graininess information obtained by the obtaining unit, the second graininess information obtained by the obtaining unit, and the third graininess information predicted by the predicting unit; and a correction unit configured to correct the image forming condition selected by the selecting unit.