1. An image forming apparatus, comprising: an acquisition unit configured to acquire an area in which, in image data, pixels with more than a predetermined density are successive in a main scanning direction and in a sub scanning direction; and a correction unit configured to, on a basis of a distance from an edge portion of the area acquired by the acquisition unit to a target pixel in the acquired area, correct a value of the target pixel, wherein, in correction of the value of the target pixel by the correction unit, the target pixel is sub-divided into sub pixels, and decreases a density on a sub-pixel-by-sub-pixel basis, wherein the number of sub pixels that decreases a density in the target pixel is varied on a basis of the distance, and wherein, in an area in which a plurality of pixels is successive in the main scanning direction including the target pixel, the number of sub pixels that decreases a density for at least one of the plurality of pixels is different from the number of sub pixels that decreases a density in the target pixel.