| 摘要 |
A chroma level control circuit for a television receiver is responsive to the average of selected portions of color difference signals to reduce deviations from a viewer-selected chroma level. The preferred chromal level is selected by the viewer and the automatic control circuit responds to amplitude variations in selected portions of the color difference signals to stabilize chroma level about the preferred level. A gating circuit is responsive to the demodulated color difference signals and selective of portions thereof, e.g. the positive portion of the R-Y signal, so that only selected hues are used to automatically control the chroma level by adjustment of the receiver's chroma gain controlled amplifier. The circuit is also responsive to low brightness levels in the scene to temporize chroma level control during low brightness scenes. In addition, the chroma level control circuit is frequency selective, i.e. long duration highly saturated scenes, such as a bright red background, will not be fully responded to as an undesired phenomenon requiring lowering of chroma level.
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