ADOBE AFTER EFFECTS 7.0
User Guide
404
Auto Levels clips the white and black pixels by 0.5%—that is, it ignores the first 0.5% of either extreme when identi-
fying the lightest and darkest pixels in the image. This ensures that white and black values are based on representative
rather than extreme pixel values.
See “Auto Color effect” on page 402 for explanations of this effect’s controls.
This effect works with 8-bpc and 16-bpc color.
Original (left), and with effect applied (right)
Brightness & Contrast effect
The Brightness & Contrast effect adjusts the brightness and contrast of the entire layer (not individual channels).
The center point of each slider is neutral and indicates no effect. The layer’s quality setting does not affect Brightness
& Contrast. Using the Brightness & Contrast effect is the easiest way to make simple adjustments to the tonal range
of the image. It adjusts all pixel values in the image at once—highlights, shadows, and midtones.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
Original (left), and with effect applied (right)
Broadcast Colors effect
This effect works with 8-bpc color.
The Broadcast Colors effect alters pixel color values so that the layer 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. The layer’s quality setting does not affect the Broadcast Colors effect.
Reducing saturation requires greater amplitude modification than reducing luminance to achieve the same IRE unit
level, which alters the appearance of your image more. Key Out Unsafe and Key Out Safe are intended to make it easy
for you to determine which portions of the layer 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 layer, respectively.
Summary of Contents for AFTER EFFECTS 7.0
Page 1: ...Chapter 1 User Guide...
