| 摘要 |
<p>A data carrier with at least one halftone images 10 represented by structural elements 12, whereby a predetermined symmetrical widening of structural elements 12 represents a corresponding gray level of halftone image 10. Image 10 has predetermined areas 14, 16 and 22 each having a predetermined number or screen frequency of structural elements 12, the screen frequency of structural elements 12 per unit area of area 14, 16 and 22 being different between at least two areas 14, 16 and 22 and/or structural elements 12 being offset from each other in at least two areas 14, 16 and 22. A data carrier with such a halftone image 10 acquires a moirépattern in at least predetermined areas of halftone image 10 when copied, so that a copy of the data carrier is recognizable immediately and with the naked eye (FIG. 1).</p> |
