| 摘要 |
This invention adds a graphic field to an electronic ticket. The graphic field is designed to produce a "tell" a visible known image (a large number of detectable halftone gray steps) when printed by a personal computer printer. Additionally, the graphic field will change in appearance when the ticket originally printed by the personal computer printer is digitally reproduced by either scanning or photocopying. The foregoing makes it more difficult to copy and/or forge the ticket.
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