FOCUS Enhancements Bridge/Router MX-4DV - Manual (Page 101)

C HROMAKEY P REPARING THE K EYED F OOTAGE
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P
REPARING THE
K
EYED
F
OOTAGE
Preparation of the keyed footage presents a challenge. It is the most important and most difficult
step, because the solid colored background is so crucial to the success of the illusion. To achieve
the required background requires, in most cases, special props, lighting, and other materials.
In this example, we placed our flying hero atop a platform centered on the set.
Here’s how the footage used in this example was prepared:
•
Uniquely colored fabric was draped over the back, sides, and bottom of the set. The same fab-
ric was used to wrap completely around the platform on which we posed our flying hero.
When choosing the fabric color, it was important to try and select a fabric that did not contain
any of the colors in our flying hero’s wardrobe. Professional studios generally use a bright
green or blue screen in place of the colored fabric.
• Key lights and fill lights were positioned so as to minimize glare and shadows during filming.
Light bouncing off an area produces different shades of the background color. Likewise, shad-
ows also produce varying shades. The key to successful chromakeys is to reduce as much as
possible the colors in the background.
The use of lighting filters, umbrellas, lighting stands, and similar tools can make a tremendous
difference in the quality of the chromakey as well as the amount of “post production” work
you must do to produce the exact illusion you want.
• Several test shots were made, then lighting was adjusted, the actor was repositioned, and so
forth, until the optimum results were produced.
• Final footage was then shot.
P
REPARING THE
C
HROMAKEY
F
OOTAGE
With the background footage and keyed footage recorded and available, you’re ready to combine
them into the chromakey effect. The following steps assume that source A is the background foot-
age (the traffic sequence) and source C is the keyed footage (the flying hero).
To prepare the chromakey footage:
1 If necessary, turn on the MX-4 DV and all sources.
2 Start both sources (A and C) rolling.
3 Select the background footage as the CURRENT source — that is, press CUT / A . The image
appears on the program monitor.
4 Select the keyed footage as the NEXT source — that is, press NEXT / C .
5 Press CHROMAKEY or SHIFT + CHROMAKEY to activate the effect. CHROMAKEY starts it and
uses the last chromakey setting you created; SHIFT + CHROMAKEY starts with a new chromakey
setting.