1. An image processing apparatus comprising: an attribute determination unit adapted to determine attributes of features for respective pixels of an original image scanned by an image scanning unit; and a smoothing processing unit adapted to weight pixel values included in an M×M (M is a natural number) area including a pixel of interest, to change a pixel value of the pixel of interest based on the weighted pixel values, and to apply smoothing processing to pixels in a filtering area used for the smoothing processing, wherein said smoothing processing unit reduces, to a size of an N×N (N is a natural number, M>N) area including the pixel of interest, a size of the filtering area to apply the smoothing processing in accordance with the attributes determined by said attribute determination unit.