| 摘要 |
PURPOSE:To attain the quantization of an analog picture signal in which the reproducibility of an intermediate tone is emphasized by giving the 3rd reference voltage to a tap led out of a reference voltage divider constituting a parallel comparison type A/D converter. CONSTITUTION:The peak voltage value of an analog picture signal detected and held by a background level detecotor 7 is voltage-divided sequentially by a resistance voltage divider circuit comprising resistors R1-R4, and reference voltages VREF1-VREF3 are given to the reference voltage divider 1 constituting the parallel comparison type A/D converter together with a high speed comparator group 2 and an encoder 3. In setting the 3rd reference voltage VREF3 so that a voltage between the taps H and M is made larger than a voltage between the taps M and L, a reproduced picture with high quality where the intermediate tone in black surplus parts is emphasized is obtained. |
