1. An image processing apparatus for correcting image distortion, comprising: a storage configured to store before-correction coordinates in a coordinate system of a before-correction image, corresponding to each pixel in a coordinate system of a corrected image; a coordinate output section configured, when coordinates to select each pixel of the corrected image are input, to read the before-correction coordinates corresponding to the input coordinates, from the storage and output the before-correction coordinates; a pixel data output section configured to output the data of the before-correction image, corresponding to the before-correction coordinates output from the coordinate output section, as the data of the pixel of the corrected image, corresponding to the before-correction coordinates; and a pixel data calculator configured, when the before-correction coordinates output from the coordinate output section include a value after the decimal point, to calculate a weighted average based on the data of a plurality of pixels close to the before-correction coordinates in the before-correction image to output the weighted average as the data of the pixel of the corrected image, corresponding to the before-correction coordinates.