An image processing apparatus is provided with an area sensor which is formed by arranging sensor components for a pixel in a two-dimensional array and is attached in an inclined manner with respect to a reference installation position. The apparatus has a sensor unit which reads, from the sensor components which are determined based on an inclination angle indicating an inclination of the area sensor from the reference installation position and have been arranged within the area sensor, image data in which the inclination has been corrected; an image obtaining unit which obtains a plurality of frames of image data having a shift of less than one pixel, by scanning an original document image once by the sensor unit; and a high resolution conversion unit which obtains image data with a resolution higher than resolutions of the sensor components by using the obtained image data to perform interpolation processing.