An image input apparatus includes a show-through elimination part performing show-through elimination on image data read from a front face of an original and image data read from a back face of the original. An image compression part compresses and converts, into codes, the image data of the front face and the back face from which image data show-through is eliminated. The show-through elimination part uses the image data of the back face when performing the show-through elimination on the image data of the front face and uses the image data of the front face when performing the show-through elimination of the image data of the back face.