| 摘要 |
PURPOSE:To balance picture quality so that the distortion of a luminance signal when illuminance is high or an SN ratio when he illuminance is low is given priority by varying the amplification gain of the luminance signal with the illuminance of a subject and then varying the mixing ratio of the luminance signal according to the illuminance. CONSTITUTION:An adding circuit 18 adds a high-band luminance signal YM, a low-band luminance signal YL1, and a matrix luminance signal YL to output a luminance signal to an output terminal 20. A variable gain circuit 17 is put between a low-pass filter 16 and the adding circuit 18 and a variable gain circuit 19 is interposed between a matrix circuit 10 and the adding circuit 18. When the illuminance is high and the SN ratio of the signal is good, the gain of the variable gain circuit 17 is small and the gain of the variable gain circuit 19 is large. The variable gain circuits 17 and 19 are varied continuously to obtain high picture quality with small luminance distortion when the illuminance is large, or increase the sensitivity by using a luminance signal with a good SN ratio when the illuminance is small.
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