An image processing apparatus is configured to extract contour information of a medium area from readout image data, and correct distortion of the medium area based on the contour information. The medium area is an area for image data corresponding to a medium serving as a reading target. The image processing apparatus includes an acquiring unit that acquires the readout image data, an extracting unit that extracts the contour information of the medium area from the readout image data, a displaying unit that displays the contour information so as to superpose the contour information on the readout image data, a detecting unit that detects an instruction of changing a position of the contour information. The extracting unit extracts again the contour information by reflecting the instruction of changing, and the displaying unit redisplays the contour information extracted again by the extracting unit.