An image data processing method is provided. In this method, a plurality of original pixel values of an image is input. An interpolation position of a target pixel in the image is determined. Whether the interpolation position is in a central region of an object or in a marginal region of an object is determined. A pixel value interpolation with respect to the interpolation position is performed. When the interpolation position is in the central region of an object, the pixel value interpolation is performed in a first calculation mode, and when the interpolation position is in the marginal region of an object, the pixel value interpolation is performed in a second calculation mode, wherein the first calculation mode may be a low pass filtering interpolation mode, and the second calculation mode may be a linear interpolation mode.