1. An image processing apparatus, for processing original image data representing a captured color image that has been subjected to photoelectric conversion, comprising: an estimation unit that generates estimated color fringing information representing an estimate of color fringing in the captured image on the basis of the original image data; a removing unit that employs the estimated color fringing information to generate modified image data based on the original image data so as to compensate for such color fringing in at least a part of the captured image; and a region determination unit that determines whether a pixel of the original image data is in a first region, in which a first color is not saturated and a second color is saturated, or in a second region, in which neither said first color nor said second color is saturated, the first region being between the second region and a further region in which said first and second colors are both saturated, the second color being a color for which color fringing is to be removed by said removing unit, and the first color being a reference color, wherein the estimation unit employs a first estimation method to generate said estimated color fringing information for pixels that the region determination unit determines are in said first region, which first estimation method increases the estimated color fringing information the further the pixel is in the direction away from said further region, and further employs a second estimation method, different from said first estimation method, to generate said estimated color fringing information for pixels that the region determination unit determines are in said second region, which second estimation method decreases the estimated color fringing information the further the pixel is in the direction away from the first region.