ADOBE PREMIERE PRO 2.0
User Guide
346
Video effects
Broadcast Colors effect
The Broadcast Colors effect alters pixel color values so that the clip can be accurately represented in a television
broadcast. Computers represent colors as combinations of red, green, and blue. Consumer video equipment repre-
sents colors using different composite signals. Home video equipment cannot reproduce signals above a certain
amplitude, and computer-generated colors can easily exceed this limit. (Signal amplitude is measured in IRE units;
120 IRE units is the maximum possible transmission amplitude.) Use the Broadcast Colors effect to reduce
luminance or saturation to a safe level.
To achieve the same IRE level as an image with reduced luminance, reducing saturation requires greater amplitude
modification, which alters the image more.
Key Out Unsafe
and
Key Out Safe
make it easier for you to determine
which portions of the image will be affected by the Broadcast Colors effect at the current settings. If you make your
background a contrasting color and temporarily select
Key Out Unsafe
or
Key Out Safe
, the background will be visible
through affected or unaffected areas of the clip, respectively.
An unsafe level simply means that if some portions of your sequence exceed the safe level, they will not look as you
intended when viewed on a television monitor. Here are some guidelines for using color in movies intended for
broadcast:
•
Avoid using highly saturated colors. For example, a red value of 255 used with green and blue values of 0 will cause
red to smear on an NTSC monitor.
•
Avoid pure black and pure white values. Commonly used values for black and white are 16 and 235, respectively.
•
Render a test of your sequence and play it back on an NTSC monitor to ensure that colors are represented
accurately.
Note:
The output you are creating should determine whether you use this effect. Many video cards, on output, automat-
ically reduce luminance or saturation to safe levels.
The Broadcast effect has the following options:
Broadcast Locale
Specifies the type of broadcast standard you intend to use.
NTSC
(National Television Standards
Committee) is the North American standard. It is also used in Japan.
PAL
(Phase Alternating Line) is used in most
of Western Europe and South America.
How To Make Color Safe
Specifies the method of reducing the signal amplitude:
•
Reduce Luminance
Reduces a pixel’s brightness by moving it towards black. This is the default setting.
•
Reduce Saturation
Moves the pixel toward a gray of similar brightness, making it less colorful.
•
Key Out Unsafe
Makes unsafe pixels transparent.
•
Key Out Safe
Makes safe pixels transparent.
Maximum Signal
Specifies the IRE unit level above which your clip’s pixels are altered. The range is Amplitude (IRE)
from 90 to 120 IRE. A level of 100 can affect a clip noticeably; a level of 120 is the maximum possible IRE and is risky.
The default, 110 IRE units, is conservative.
Field Interpolate effect
The Field Interpolate effect recreates a missing field (usually the odd or even scan lines, common to television or
interlaced monitors, that have been dropped during capture) by using line averages. This effect can be useful for
full-screen output, where a missing field is likely to be noticeable.