1. An image processing apparatus for vectorizing an object contained in an image, comprising; a calculation unit configured to specify an evaluation-target area that tends to produce distortion in the object, and configured to calculate amount of distortion produced in vectorization of the object by comparing between the shape of the object and the shape of a vectorized object obtained by vectorizing the object in the specified evaluation-target area; and a revising unit configured to revise the shape of the vectorized object in the evaluation-target area so as to approach the shape of the object when the amount of distortion is larger than a predetermined reference value.