1. An image processing apparatus, comprising: at least one processor functioning as: a processing unit that performs edge enhancement processing for an edge portion in an image; and, an output unit that outputs an image for which the edge enhancement processing has been performed by the processing unit, wherein the processing unit decreases the edge enhancement processing to be applied to a target pixel which is an edge portion in an image, based on a sum of values indicating brightness of the plurality of pixels around the target pixel, wherein the plurality of pixels around the target pixel are pixels on four vertexes of an area consisting of n×n pixels that include the target pixel at a center.