Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 400

Modifies alpha channel values.
Modify Alpha
Note: If you apply Colorama to a layer with an alpha channel, and the Output Cycle doesn't contain alpha information,
the anti-aliased edges of the layer may appear pixelated. To smooth the edges, deselect Modify Alpha. If Modify Alpha is
selected and the Output Cycle contains alpha information, the output is affected even if you've selected None from the
Modify menu. Using this method, you can adjust the levels of just the alpha channel without also changing the RGB
information.
The Colorama effect's influence extends to transparent pixels. (This setting works only if
Change Empty Pixels
Modify Alpha is selected.)
Pixel Selection, Masking, and other controls
These controls determine which pixels are affected. For the Matching controls for Pixel Selection to work, Matching
Mode must be set to anything other than Off.
The center of the range of colors of pixels to be affected by the Colorama effect. To select a specific
Matching Color
color in the image using the eyedropper, turn off the Colorama effect temporarily by clicking its Effect switch
the Effect Controls panel.
How far a color can be from Matching Color and still be affected by the Colorama effect. When
Matching Tolerance
Matching Tolerance is 0, only the exact color selected for Matching Color is affected by Colorama. When Matching
Tolerance is 1, all colors are matched; this value essentially turns Matching Mode off.
How smoothly the matched pixels blend into the rest of the image. For example, if you have an
Matching Softness
image of a man wearing a red shirt and blue pants, and you want to change the color of the pants from blue to red,
subtly adjust Matching Softness to spread the matching from the blue in the pants into the shadows of the pants folds.
If you adjust it too high, the matching spreads to the blue of the sky; if you adjust it even higher, the matching spreads
to his red shirt.
What color attributes are compared to determine matching. In general, use RGB for high-contrast
Matching Mode
graphics and Chroma for photographic images.
The layer to use as a matte. Masking Mode specifies what attribute of the Mask Layer is used to define
Mask Layer
the matte.
Shows modified pixels composited on top of the original layer. Deselect this option to show
Composite Over Layer
only modified pixels.
The effect's transparency. The result of the effect is blended with the original image, with the
Blend With Original
effect result composited on top. The higher you set this value, the less the effect affects the layer. For example, if you
set this value to 100%, the effect has no visible result on the layer; if you set this value to 0%, the original image doesn't
show through.
Curves effect
The Curves effect adjusts the tonal range of an image. You can also use the Levels effect, but the Curves effect gives
you more control. With the Levels effect you make the adjustments using just three controls (highlights, shadows,
and midtones), but with the Curves effect you can arbitrarily map input values to output values using a curve defined
by 256 points.
You can load and save arbitrary maps and curves to use with the Curves effect.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
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