| 摘要 |
The system combines first and second composite video signals into a resulting composite video signal. The first composite video signal represents a foreground scene having a first trichromatic moving picture region which envelopes a second trichromatic backing region through a trichromatic transition region. The second composite video signal represents a background scene. A gain controlling circuit produces from first component video signals first and second analog signals (1- alpha ), ( alpha ) which control in proportion the amplifications of the first and second composite video signals to obtain second output composite video signals. The first analog signal has first and second levels when the first component video signals are representative of the first and second picture regions and has intermediate levels lying between the first and second levels when the first component video signals are representative of the transition region. A video mixer mixes the first and second output composite video signals into the resulting composite video signal.
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