| 摘要 |
An electronic system for the purpose of generating special effects in both color TV and color motion pictures is disclosed. A luminance key amplifier determines the average strength of matrixed red, blue and green video signals from a foreground camera and compares the average with a reference value. Areas of the foreground image that cause the average strength of the color signals to exceed the reference value, such as white, cause the luminance key system to key the green, blue and red signals from a background source such as a camera to an encoder, a video tape recording system or a film recording system. When the average strength of the red, blue and green signals from the foreground camera is less than the reference value, such as black or gray, the luminance key amplifier responds by passing the color signals from the foreground camera only to the encoder, video tape recording system or film recording system.
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