| 摘要 |
A document security system is provided by providing each document with a synthetic watermark, for instance using the process, compositions and apparatus disclosed in the aforementioned U.S. patent of Norris, et al and, within the perimeter of at least one of the symbols which is provided by the synthetic watermark, an identical complementary or otherwise corresponding symbol is printed using ink, paint, dye, stain or similarly contrastingly pigmented substance so as to create, in combination with the synthetic watermark a juxtaposition that can be looked-for as evidence that the document is genuine and its serial number unaltered. |
