NewTek TriCaster 855 - Manual (Page 212)

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11.7 PRACTICAL STAGING FOR LIVEMATTE
We’d like to offer a few suggestions here to guide you in preparing, so you get the most out of
LiveMatte.
LIGHTING 11.7.1
The single most important aspect of ‘pulling a clean key’ is lighting. The lighting should be even
and diffuse. Hotspots and shadows create different green or blue shades on the wall, and
overexposed areas lack sufficient color for clean keying. (It is not how much light you have on
the key wall, but how evenly lit that wall is.) Naturally, you want to keep your green (or blue)
screen clean and free of wrinkles, ripples, folds, tears, or other blemishes, as well.
Second, the distance from your talent to the screen behind can make a profound difference in
key quality. When the subject stands too close to the key colored background, the key color
reflects back onto the subject, creating a green or blue fringe that is difficult to remove. If you
have available space, move your subject farther away from the wall.
When good distance is out of the question, you can improve things somewhat by placing lights
above and behind the talent, lighting them from behind with a complimentary color filter over
the light to ‘cancel out’ unwanted reflection (for green use a magenta filter; for blue, orange or
amber.
Don’t overdo back (or top) lighting, however. The limited dynamic range of the camera means
there will be little useful color data in badly over-exposed highlights. This can make it next to
impossible to separate fringe zones (such as hair detail) from the background (especially when
this is also overexposed).
CONNECTION CONSIDERATIONS 11.7.2
As mentioned above, washed-out areas in the video signal lack sufficient color information to
provide good separation. For similar reasons, it’s worth considering the color characteristics
different types of video signals.
SDI connections are ideal, if you can use them. Otherwise, in the analog video realm you will
encounter three main types of camera connections. We present them here in ascending order