PrintOnImage is described as 'virtual printer that can work with a document made by any Windows application, crop and save it to the graphics file. Basically, it lets you to print right on the image file!'. There are four alternatives to PrintOnImage for Windows and Mac. The best alternative is Image Printer. It's not free, so if you're looking for a free alternative, you could try Spool Pilot. Other great apps like PrintOnImage are Zan Image Printer (Paid) and Ultra Image Printer (Paid).
Spool Pilot makes it possible to convert printouts from arbitrary applications in several popular graphic formats as easily as it is now to save them in a PDF file. From the point of view of the user, the procedure of saving printouts is very much the same.