| 摘要 |
<p>A security document according to the present invention includes a document substrate having a surface for receiving printed indicia. A half tone warning image is printed on first areas of the surface and a half-tone background image is printed in second areas surrounding the first areas. The half-tone a warning image includes at least one word indicating a status of a copy of the document. A camouflage image extending over the document surface for confusing the eye of an observer such that said warning image is not readily observed. The camouflage image includes at least one word indicating to an observer a status of the original document. One of the half-tone warning image and the half-tone background image are printed with half-tone elements of such a line spacing and element size that it is not readily reproducible by a photocopier. As a consequence, the half-tone warning image becomes apparent on photocopies of the original document.</p> |
