| 摘要 |
PURPOSE:To improve picture quality regardless of whether illuminance is high or low by providing a mixing means which mixes low-frequency chrominance components with a wide-band luminance signal and a varying means which varies the quantity of mixture of the mixing means according to the brightness of an object. CONSTITUTION:The varying means 19 varies the quantity of mixture of the mixing means 18 according to the brightness of the subject. A variable gain amplifier 17 amplifies the wide-band luminance signal Yw with which low-fre quency chrominance components are mixed by the mixing means 18. The mixing means 18 is composed of an adding circuit and the varying means 19 consists of a variable gain amplifier which amplifies a low-frequency chrominance compo nent of green (G chrominance component) among plural low-frequency chrominance components. When the illuminance of the subject is high and the S/N ratio is high, the gain of the variable gain amplifier as the varying means is large and the gain of the variable gain amplifier 17 is small. Further, when the illuminance of the subject is low and the S/N ratio is low, the gain of the variable gain amplifier as the mixing means 19 is small and the gain of the variable gain amplifier 17 is large.
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