| 摘要 |
A composite image arrangement, for use as an anti-counterfeiting measure on documents of value, comprises two substantially parallel patterns, each having relatively more (3, 4) and less (2, 5) light-transmissive regions. The patterns appear random in isolation, and are in fixed positions on either side of a light transmissive lamina (1) and precisely aligned to give a non-random transmitted image when viewed together in transmission. The transmitted image may be visible in a restricted range of angles only. A method of manufacturing such an arrangement comprises (a) providing a random two-tone pixel pattern, (b) providing a non-random two-tone image pattern, (c) combining the image pattern and the pixel pattern using a combining function (for example, exclusive or) to form a further random pattern, and (d) aligning the two random patterns on either side of a light-transmissive sheet (for example, paper) to give an approximation of the image pattern when viewing both random patterns together in transmission. |
