NewTek TriCaster TC1 (2 RU) - Manual (Page 156)

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SECTION 13.4
COMPOSITING
When you enable (and configure) LiveMatte for an input, the onscreen monitor for that input shows the
source keyed over a checkerboard pattern (when the Checkerboard option is selected in Overlays for the
monitor.)
If you select the ( LiveMatte -enabled) input as Input A in an M/E tab in LiveMatte mode , the keyed source is
overlaid on sources in lower input rows. You will see the composite result when the output is assigned to
either the
PGM or Preview row.
SECTION 13.5 FINE TUNING
You’ll find LiveMatte easy to configure with a little experimentation – but a few handy workflow tips follow
below.
You may find it useful initially to turn Smoothness off or nearly so. Likewise begin with a low value for
Tolerance – perhaps just 5-10, or so. Put the video source on Preview or Program Output before you do so, to
provide a larger view to help you assess your settings.
Pick your primary Color , but – before releasing the mouse button – slide the eyedropper around to different
parts the background. Watch the monitor as you do so to see how the area of transparency is affected by
different Color choices. Release the mouse when you find the color that produces maximum results. It’s
often preferable to pick an ‘average’ color from a location fairly close to the boundary between the
background and foreground regions.
Now you can start to ramp up Tolerance . Bring it up slowly until most of the background color has been
eliminated, cutting away most of the background to within a few pixels of the foreground/background
boundary. Now raise
Smoothness t o fine tune that edge region, and you’re nearly done.
Before considering your settings final, make sure to test the result using a moving source. This will
sometimes reveal that overly aggressive settings cause small ‘blocks’ of pixels in the edge region to appear
to snap on and off during motion - as they either qualify or disqualify for inclusion in the resulting matte. (A
little reduction in
Tolerance and increase in Smoothness will usually resolve this problem.)
Hint: It can be useful to zoom in using Position controls when fine tuning LiveMatte.
SECTION 13.6
LIGHTING FOR LIVEMATTE
We’d like to offer a few suggestions here to guide you in preparing your set. The single most important aspect
of ‘pulling a clean key’ is lighting. The lighting should be even and diffus e. Bright ‘h otspots ’ and shadows
create different 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.