1. An image processing apparatus for an image pickup device including a plurality of color filters, the image processing apparatus comprising: a determination unit adapted to determine a region in which a signal level for a color plane of image data produced by the image pickup device, corresponding to at least one of the plurality of color filters, or a signal level for a brightness plane produced from the image data exhibits a monotonic increase or a monotonic decrease in a predetermined section of the region, as a color fringing region in which color fringing occurs; an estimation unit adapted to estimate an intensity of the color fringing according to a difference in signal intensity between a plurality of color planes of the image data corresponding to the plurality of color filters in the color fringing region; and a removal unit adapted to reduce the color fringing in the color fringing region based on the estimated intensity of the color fringing in the color fringing region.