| 摘要 |
In a scene-by-scene color corrector, automatic color correction circuitry produces color correction signals which are stored and utilized in preparing color-corrected video tape. Preferably, the automatic correction circuit tests only a pre-selected portion of the video picture displayed on a monitor. This portion or "window" is visible on the monitor screen, and its position and size can be changed as desired. The use of the "window" permits the exclusion of portions of the picture on which the automatic circuitry is less than fully effective, or which do not have components desirable for use in automatic color correction. If a separately variable luminance signal is produced, the automatic color correction circuitry preferably uses the luminance signal as a reference, thus allowing one to maintain color balance despite changes in the luminance signal. A scene-change analyzer determines whether the average window signal level in at least a portion of one field is different from the average window signal level in at least a portion of another field by a predetermined amount, and if so, it provides a suitable output signal. A scene-change analyzer may be used in a color corrector for scene-by-scene corrections. The film or tape transport may be stopped after a scene-change signal is produced, and the color correction values may be adjusted while the film or tape is stopped. Alternatively, the transport may continue to move the film or tape after a scene-change signal is produced, and the color correction values may be adjusted while the film or tape is moving.
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