| 摘要 |
PURPOSE:To accurately perform the electrical control of a dynamic range for an input system for video signals by changing the set value of the offset or the gain of an adjusting means when the density mean value and the dispersion value of the digital picture signals are not kept within a prescribed range so that these values are set within the prescribed range. CONSTITUTION:The digital picture signals obtained from the input picture signals which are digitally converted via an adjusting means which adjusts the offset and the gain of the picture signal and an A/D converter 27 which converts the picture signals into the digital picture signals are stored in a frame memory 28. Then the density means value and the dispersion value are obtained for the digital picture signals of the memory 28 and it is checked whether these values are kept within a prescribed range or not. If not, the set value of the offset or the gain of the adjusting means is changed so that said means value and dispersion value are set within the prescribed range. In other words, the input picture data is converted so that a distribution near the normal one can be obtained. Thus it is possible to accurately perform the electrical adjustment of a dynamic range for an input system of video signals.
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