| 摘要 |
A circuit for detecting a specified color in a color image signal operates on first, second and third primary color signals from a color camera. A complementary color, resulting from additive mixing of two primary colors, is detected by taking the sum and differences of the signal representing the two primary colors. The third primary signal is subtracted from the sum signal to produce a vector sum signal and the difference signal is rectified. The signal which indicates the presence of a complementary color is generated by subtracting the rectified signal from the vector sum signal and comparing it to a fixed reference level. A primary color is detected by subtracting the sum signal from the third primary signal to produce the vector sum signal. Fine adjustment of the target color is obtained by amplifying the two primary color signals differentially to maintain a constant sum of the two primary color signals.
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