| 摘要 |
<p>A data carrier has at least one half-tone image (10) generated by structure elements (12). A predetermined symmetrical enlargement of the structure elements (12) represents a corresponding degree of grey of the half-tone image (10). The image (10) has predetermined areas (14, 16 and 22) in which a predetermined number of structure elements (12) is arranged. The number of structure elements (12) in the surface of each area (14, 16 and 22) differs between at least two areas (14, 16 and 22) and/or the structure elements (12) are mutually offset in at least two areas (14, 16 and 22). When a data carrier with such a half-tone image (10) is copied, a moiré pattern is generated in at least certain predetermined areas of the half-tone image (10), so that a copy of the data carrier is immediately visible to the naked eye.</p> |
