| 摘要 |
PURPOSE:To improve the resolution of density difference by amplifying differentially a picture signal together with a constant voltage to amplify and expand only a part near a required optional density levle of the picture signal and converting this part digitally. CONSTITUTION:A picture signal Video from a television camera 1 is connected to the positive input terminal of a differential amplifier 4, and a DC variable power source 5 and two resistances 6 and 7 are connected to the negative input terminal of this differential amplifier 4, and the other terminal of the resistance 6 out of resistances 6 and 7 is grounded, and the other terminal of the resistance 7 is connected to the output of the differential amplifier 4, and the output of the differential amplifier 4 is connected to an A/D converter 2, and two diodes 3a and 3b for limitting the amplitude are connected to the output of the differential amplifier 4, and one diode 3a out of these two diodes 3a and 3b has the other terminal grounded, and the other diode 3b has the other terminal connected to a power source voltage +VCC. |
