NewTek TriCaster Studio - Manual (Page 204)

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10.1 LIVEMATTE
Really, LiveMatte is the only part of this that requires much of you, the TriCaster user; and even
this bit is quite simple. Please refer back to Sections 5.2.6 and 6.7 for guidance on using the
LiveMatte controls.
LiveMatte is an excellent keyer. Even so, it’s crucial to start with good planning and physical
preparation (if you’re thinking, ‘I know – garbage in, garbage out’, you’re very astute).
10.1.1 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 and LiveSet.
LIGHTING
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 an ‘edge’ 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!)