1. An image forming apparatus comprising: an image bearing member capable of bearing an electrostatic image; a development device which includes a developer bearing member to bear a developer and which develops an electrostatic image on the image bearing member; and a controller which controls discharge operation to discharge a developer having polarity opposite to normally charged polarity to the image bearing member by forming a electric field, which is larger than image forming is performed, to force a developer having opposite to normally charged polarity from the developer bearing member to the image bearing member during image forming is not performed, wherein the controller controls the discharge operation based on at least information corresponding to an edge portion of an output image.