| 摘要 |
PURPOSE:To obtain symmetrical, stable video signals by quantizing faithfully analog video signals obtained from an optical system. CONSTITUTION:An optical system sensor unit 4A consists of a charge coupled element CCD, an amplifier etc., and converts light 41 obtained by scanning a recording medium to an analog video signal and amplifies. Amplified analog video signal 42 is inputted to an analog/digital conversion (A/D conversion) unit 4B and digitized. Digitized video signal 43 is inputted to a quantizing circuit 4C and quantized. The quantizing circuit 4C converts video signal at objective position of quantizing on paper into three-dimensional signal by a three-dimensional circuit 4C-1, and sets some surroundings, making surrounding nearest from the video signal the first surrounding and so on, and sets slice level of video signal at objective position of quantizing for each surrounding by a slice level detecting circuit 4C-2. The video signal is sliced by the slice level in a comparator circuit 4C-3 and quantized.
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