| 摘要 |
<p>A method and system for sensing a characteristic (e.g. translucency) of a document (10) utilises radiation (17) from a specific window area (16) of the document (10). The radiation (17) is sensed by a sensor (18) with pixel dissection (P1 - P3), that affords pixels (P2) of a central location of the window area (16), a greater (x2) weighting so as to attribute enhanced significance to the central portion of the window area (16), whereby tolerance to misalignment with respect to the window area (16) is increased. Data signals in accordance with the weighted pixel signals are compared (62 Fig 3; 120 Fig 6) with stored values (64 Fig 3; 122 Fig 6) for the purpose of document authentication (66 Fig 3; 124 Fig 6). Pixel-weighting techniques used include filtering incident and transmitted light (46, 54 Fig 3, Fig 4), algebraically weighting derived signals (Figs 5, 6), and overlapping the sensed pixels (Fig 7).</p> |
