1. An image processing apparatus comprising: a first detection unit configured to detect, as an irregularity area, an area where development processing is irregular in imaging data based on a regularity of a color filter array (CFA) pattern; a second detection unit configured to detect, as approximate areas, at least two areas having approximate feature amounts in the imaging data, wherein the approximate feature amounts of each of the approximate areas have a difference that is equal to or less than a predetermined threshold; and a specifying unit configured to specify an altered region in the imaging data altered by regarding an overlapping region of the irregularity area and the approximate areas as the altered region, wherein each of the first detection unit, the second detection unit, and the specifying unit is implemented using a processor.