Image forming apparatus capable of setting print start position for back side of recording paper sheet based on margin formed by reducing image for back side in size

An image forming apparatus comprising:

• an image forming device that performs duplexing by forming a front-side image on a front side of a recording paper sheet and forming a back-side image on a back side of the recording paper sheet;
• and
• a control device that includes a processor and functions, through the processor executing a control program, as
• (i) a controller that allows the image forming device to perform the duplexing based on front-side image data for front side and back-side image data for back side,
• (ii) an image processor that creates a reduced-size image obtained by reducing an image represented by the back-side image data from an original size represented by the back-side image data at a ratio of size reduction predetermined according to a ratio of magnification from a first shrunk state of the recording paper sheet with the front-side image formed but the back-side image not yet formed to a second shrunk state of the recording paper sheet having both the front-side image and the back-side image formed thereon and larger in size than the first shrunk state so that respective sizes of the back-side image and the front-side image on the recording paper sheet are equal to respective original sizes indicated by the front-side image data and the back-side image data, and
• (iii) an image corrector that performs a correction, on image data representing the reduced-size image, to allocate a margin formed by the size reduction of the image represented by the back-side image data to a trailing end side of the recording paper sheet in a direction of conveyance of the recording paper sheet without allocating the margin to a leading end side of the recording paper sheet in the direction of conveyance,
• wherein the controller allows the image forming device to form an image represented by the front-side image data on the front side of the recording paper sheet and allows the image forming device to form the reduced-size image on the back side of the recording paper sheet according to the allocation of the margin.