| 摘要 |
PURPOSE:To improve S/N and good coloring even under a low illuminance by applying a signal processing so that coloring is increased to a larger output signal level of an image pickup tube and coloring is decreased to a smaller output signal level. CONSTITUTION:An image pickup signal from an image pickup tube 1 is fed to an AGC circuit via a preamplifier 2. An output adjusted to a prescribed level by the AGC circuit 3 is fed to LPFs 4, 5 and a BPF6. A luminance signal is separated by the LPF4 and the result is fed to an encoder 9 via a gamma correction circuit 7 and an aperture correction circuit 8. On the other hand, a color signal separated from the BPF6 is formed into R and B signals by a color separation circuit 10 and divided into a route of a gamma correction circuit 12 or an amplifier 13 by a switch circuit 11. A luminance signal outputted from the LPF5 is also divided into a path of a gamma correction circuit 17 or a path of an amplifier 18. The switch circuits 11, 16 are switched by an AGC control signal 20, resulting that a video image with high S/N and good coloring is outputted.
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