Videonics MXPro, Руководство пользователя

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Chapter 10 Videonics MX-Pro User Guide
Chroma Key requires careful preparation of the input sources to achieve the desired
effect. Keep the following points in mind:
• The color used for the background must not appear elsewhere in the image. For
example, if Kong’s head (in the example above) contains colors close to the
chroma key background, the picture of the bridge would appear in those areas.
(Professionals often use a special “blue screen” paint for the backdrop when film-
ing the image.)
• The color of the background must be evenly distributed. Glare from camera
lights and shadows of the subject can alter the background color. MXPro’s
chroma key circuitry might not be able to handle the different values, thereby
spoiling the illusion.
This chapter explains how to prepare footage for use with the Chroma Key feature. Of
course, screen images appear in grayscale in this book.
The Background footage shows traffic moving along a freeway or highway.
The Keyed footage, specially prepared, shows our intrepid hero flying against a solid
colored background.
The Chroma Key footage is the result of combining the Background footage and Keyed
footage using the MXPro Chroma Key feature.
P
REPARING THE
B
ACKGROUND
F
OOTAGE
Preparation of the Background footage does not require anything special. It might be
footage of automobile traffic taken from a bridge.
Tip
The more unusual or dramatic the Background footage the greater the final effect of the
Chroma Key.
Background
Footage
Keyed
Footage
Chroma Key
Footage