| 摘要 |
<p>A light source 26 illuminates an information area on a document, the reflected light being detected by a sensor 38. A filter circuit equalizes the outputs of the sensor to produce an equalized video signal. The equalized video signal is then registered in a memory to represent the background signature of the information area. The registered background signature is then used as a reference for comparison with subsequent equalized video signals to produce corrected video signals, the registered background signal being updated as necessary in response to sensed white areas of the document. <IMAGE></p> |
