An image forming apparatus comprising: a document setting part for setting documents; an image input part for obtaining image data from documents set on said document setting part; an image output part (122, 144, 145) for printing or sending at least a part of the image data obtained from said documents; a control file storing part for storing at least one control file including image output settings data; a controller operable if a part of the image data obtained from a predetermined document included in said documents is a control image to retrieve a control file from said control file storing part corresponding to said control image and to control said image output part to output at least a part of said image data other than image data of said predetermined document in accordance with the image output settings data of the retrieved control file; wherein the image forming apparatus prints a control image on a medium so as to generate said predetermined document on which the control image is drawn; and wherein each control file uniquely corresponds to a control image and the control file corresponding to a control image can be obtained from information (711, 714) indicated on the control image; characterized in that one of the control image data and the control file includes a user code, and if the user code of the control image data or the control file and a user code input into the image forming apparatus separately from the control image data are the same, the image forming apparatus outputs at least a part of said image data other than image data of said predetermined document in accordance with the image output settings data. a document setting part for setting documents; an image input part for obtaining image data from documents set on said document setting part; an image output part (122, 144, 145) for printing or sending at least a part of the image data obtained from said documents; a control file storing part for storing at least one control file including image output settings data; a controller operable if a part of the image data obtained from a predetermined document included in said documents is a control image to retrieve a control file from said control file storing part corresponding to said control image and to control said image output part to output at least a part of said image data other than image data of said predetermined document in accordance with the image output settings data of the retrieved control file; wherein the image forming apparatus prints a control image on a medium so as to generate said predetermined document on which the control image is drawn; and wherein each control file uniquely corresponds to a control image and the control file corresponding to a control image can be obtained from information (711, 714) indicated on the control image; characterized in that one of the control image data and the control file includes a user code, and if the user code of the control image data or the control file and a user code input into the image forming apparatus separately from the control image data are the same, the image forming apparatus outputs at least a part of said image data other than image data of said predetermined document in accordance with the image output settings data.