1. An image processing apparatus comprising: a divider, arranged to divide an input image into band images each including a predetermined number of lines so that an overlap area exists between neighboring band images; an extractor, arranged to extract candidate pixels which form an image region exhibiting poor color tone for each band image; and a decider, arranged to decide the band image which is to undergo a characteristic amount determination for the extracted candidate pixels, based on the position of a candidate region including the candidate pixels in the overlap area.