1. An image processing apparatus, which generates image data by functionally approximating a contour of an object using anchor points and control points, and processes the image data, comprising: a classification unit configured to classify the anchor points that define the contour of the object into a plurality of groups based on features of the contour of the object, wherein said classification unit classifies the anchor points into a first group including anchor points which meet one of the features of the contour of the object and a second group including anchor points which do not meet any of the features of the contour of the object; a saving unit configured to save the anchor points classified by said classification unit for the first group, wherein said saving unit does not save the anchor points classified into the second group; and an output unit configured to execute rendering using the anchor points classified into the first group and an anchor point which is located on a curve determined by the anchor points classified into the first group and is classified as the second group, and outputs a rendered result as the object.