The invention seeks to suitably adjust the amount of a toner reduction in accordance with the type of image (object). To attain this object, an image forming apparatus according to the present invention comprises a discrimination unit for discriminating types of objects contained in input data; and a processing unit for applying reduction processing, which suppresses amount of colorant, to a thin line in a graphics if result of discrimination by said discrimination unit is that an object is a graphic;wherein whether reduction processing is to be executed or not can be selected by a user.