Sony DVS-7250, Операционное программное обеспечение

Страница: 235 / 542

Chapter 5 Chroma Keying
5-21
Additive Mix
When you are using the enhanced chroma key function, in the SETUP
(CHROMA KEY) menu an additive mix is possible.
Using an additive mix to combine images
In normal chroma keying, a key signal is used to cut a hole in a background,
and this is combined with a foreground cut out by the key signal. In an
additive mix, however, the foreground is combined unaltered (without the
effects of a key signal).
In practice it is necessary to replace the blue background of the foreground
signal by black, and for this purpose the color cancel function (see page 5-9)
is used.
This additive mix is effective to provide a realistic combined image when it
includes translucent objects such as objects made of glass.
To use an additive mix to combine images, in the SETUP menu, press F10
(KEY MIX), to select “ADD”.
Note
When using an additive mix to combine images, be sure to use the color
cancel function to change the blue background to black.
Using the plane function
In an additive mix, since no key is applied to the foreground, any variations
in the blue background show up in the combined image. To avoid this, a
particular intensity level for the blue background can be set, and the portions
of lower intensity forcibly changed to black.
Use the following procedure.
1
In the CHROMA KEY menu, select item 2 (ADJUST).
The ADJUST menu appears.
2
In the ADJUST menu, press F10 (PLANE), turning it on.
This enables the plane function.
(Continued)