Disclosed is an image forming system, in which the printer controller is capable of performing the re-RIP (Regeneration Raster Image Processing) in conformity with the revised page order accepted from the image forming apparatus. When determining that the re-RIP is necessary, the image forming apparatus transmits a regeneration request including revised page order information, changed from the original page order, to the printer controller. Receiving the regeneration request, the printer controller reapplies the rasterization processing to the print data while using the data stored in advance in the storage section, to regenerate the revised image data corresponding to the page information, and then, transmits the revised image data to the image forming apparatus. Receiving the revised image data regenerated in response to the regeneration request, from the printer controller, the image forming apparatus employs the revised image data for performing the image forming operation in regard to the print job.