An electronic file corresponding to a scanned original image is specified on the basis of the original image. If the electronic file corresponding to the original image cannot be specified, the original image is converted into vector data. The vector data is converted into image data. The first image data of the original image is compared with the second image data generated by the second conversion unit. On the basis of the comparison result, the first image data or vector data is selected as the electronic file corresponding to the original image.