1. A method for printing a watermark in a document, the method comprising: generating foreground data comprising said watermark; generating background data; applying said foreground data to a line screen to produce a foreground screened image having alternating or unequal line spacing; applying said background data to a line screen to produce a background screened image having equal line spacing; and combining said foreground screened image and said background screened image for printing as a single image; wherein said foreground screened image is not visible on a first generation version of a document that is printed; and wherein said foreground screened image is readily apparent when said first generation document is photocopied.