Adobe After Effects CS3 - Manual (Page 458)

AFTER EFFECTS CS3
User Guide
453
Apply a grain effect
Each grain effect is applied with default settings and is displayed in Preview viewing mode, which has a preview
region framed by a white border and centered on the image. The preview region displays the results of the grain effect
on just a portion of your image, for speed and comparison purposes. The grain effects are almost fully automatic but
also offer many controls to achieve precise results. You can also selectively apply the grain effects to portions of your
image using the extensive Blend With Original features provided with each effect.
1 Select the layer you want to affect.
2 Choose Effect > Noise & Grain > [effect].
3 Choose a viewing method from the Viewing Mode control in the Effect Controls panel:
Preview Displays the current settings of the applied effect in a 200x200-pixel area.
Blending Matte Shows the current color matte or mask, or the combination of both, which results from the current
settings of the Blend With Original controls group.
Final Output Renders the full active frame, using the current settings of the effect.
4 Adjust the effect’s controls in the Effect Controls panel.
The preview region in the Composition panel reflects any changes you make.
5 Choose Final Output from the Viewing Mode control.
Apply a grain effect to a selected area
The Blend With Original controls group lets you precisely apply a grain effect to a particular area of an image or
sequence by masking and matting the desired area. You can choose between two selection techniques or use a combi-
nation of both:
Color Matching Excludes any area of the image that matches a selected color. By inverting the matte, you can also
selectively process such an area.
Masking Layer Uses any layer in the current composition as a mask to selectively process or exclude an area of the
current layer or track.
When any grain effect is first applied, the Amount value of the Blend With Original controls group is set to 0%; this
value determines the percentage of blending between the original image and the processed version. At 0%, no
blending occurs and the selected effect is applied to the entire image at full strength; at 100%, white areas of the
blending matte are unchanged from the original image.
Any mask or matte works in a similar way: The white pixels in it exclude that area of the original image from
processing by the grain effect; the black pixels process normally. At 100% Amount, the white areas fully blend with
the original so that they are completely excluded from the processing. This behavior remains true when the match
is inverted. Regardless of the Amount value, the black areas of the matte or mask are always processed. The Amount
slider affects only the areas under the white pixels in the matte or mask. It affects only how the white areas of the
matte or mask are treated by each grain effect.
1 Apply a grain effect to the image.
2 Do any of the following in the Effect Controls panel:
• To create a matte around the area to which you want to apply or exclude the grain effect, use the Color Matching
controls in the Blend With Original controls group.
• To mask the current layer with another layer or track, use the Masking Layer controls.