1. An image-forming apparatus for forming a image on an image-bearing member on the basis of an original image, comprising: a platen on which an original having an original image is placed, the platen having a reference portion; means for inputting coordinates representing a predetermined area of the original placed in a surface-up condition on the reference portion; means for performing coordinate transformation from the coordinates to transformed coordinates, the transformed coordinates representing the predetermined area of the original placed in a surface-down condition; means for informing an operator of a direction to rotate the original when the operator reverses the original from the surface-up condition to the surface-down condition; an image-scanning unit, the image-scanning unit having an electric component which scans the original placed in the surface-down condition on the reference portion; and an image-forming unit, the image-forming unit having an electric component which forms an image on an image-bearing member on the basis of the original image which the image-scanning unit scanned, and which is limited to the predetermined area represented by the transformed coordinates.