1. An image processing apparatus which performs image processing for an original image obtained by reading an original, comprising: a reading unit, adapted to read an original; a first conversion unit, adapted to convert an original image read by said reading unit into vector data; a second conversion unit, adapted to convert the vector data into image data; a comparison unit, adapted to compare first image data of the original image with second image data generated by said second conversion unit; and a selection unit, adapted to select the first image data or vector data as an electronic file corresponding to the original image on the basis of a comparison result from said comparison unit, wherein said selection unit selects the first image as the electronic file corresponding to the original image if the comparison result from said comparison unit shows that the first image data is different from the second image data.