| 摘要 |
<p>Where the video image of a test piece is to be compared with stored information about a reference object, good gradation between dark and light is required. For more complicated shapes or structures a single reference level is insufficient to enable compilation of accurate data. An image synthesiser is provided with several chanels each fed from a detector scanning the incoming video signal, line by line. Each channel has a set reference level and stores appropriate light-dark information relative to its reference signal. In this manner, an accurate representation of the test object can be stored and compared with corresponding data from standard. Comparison between test piece and standard can be carried out by a computer. In one arrangement, the TV camera (T) is connected through memory units (Sp, Sp1) with onputs to the n-channels to threshold voltage level detectors (TH1, TH2, -THn) and gate elements (61, 62, 63 - 6n).</p> |
