| 摘要 |
The teachings as provided herein relate to a watermark embedded in an image that has the property of being relatively indecipherable under normal light, and yet decipherable under UV light. This fluorescent mark comprises a substrate containing optical brightening agents, and a first colorant mixture printed as an image upon the substrate. The colorant mixture layer has as characteristics a property of strongly suppressing substrate fluorescence, as well as a property of low contrast under normal illumination against the substrate or a second colorant mixture printed in close spatial proximity to the first colorant mixture, such that the resultant image rendered substrate suitably exposed to an ultra-violet light source, will yield a discernable image evident as a fluorescent mark. |
