PURPOSE: To recognize a part to be color-converted in advance by displaying the part to be color-converted on a document by performing preliminary scan on a document image before a copying operation is performed.

CONSTITUTION: An operator inputs the color of an arbitrary coordinate point on the document by the designation color coordinate input means 17 of a coordinate input device 15, or, selects arbitrary color data from color data registered on a registration color component data storage means 14 in advance, and sets a developing color before conversion. After the developing color before conversion is set, the preliminary scan is performed by depressing the preliminary scan key of a scan key 13, and the color data (b), (c), and (d), and image data (e) from an image input part 20 are inputted to a control part 18, and coordinate data (g) recognized as a color before conversion by an image processing part 25 is displayed on an LCD 12. In this way, it is possible to recognize the part to which color conversion is applied on the document and to confirm even the case where a color is scattered on the document such as a photographic document, etc.