1. An image processing apparatus comprising: a transformation unit configured to perform transformation processing on an input image based on a transformation parameter; an identification unit configured to identify transformation information related to amounts of transformation respectively between a first plurality of coordinates on a transformed image generated based on the transformation processing by the transformation unit and a second plurality of coordinates on the input image corresponding to the first plurality of coordinates; a determination unit configured to determine a smoothing parameter related to an intensity of smoothing processing for each region of the transformed image based on the transformation information identified by the identification unit; and a processing unit configured to perform smoothing processing on an image based on the input image, based on the smoothing parameter for each region determined by the determination unit.