Adobe 65008009 - After Effects CS4 Using Manual page 529

Last updated 12/21/2009
Manually reposition noise samples
Automatic grain or sample selection generally gives acceptable results for the Match Grain or Remove Grain effect, but
you can choose to manually position and resize each sample or change the sample number. For example, you may want
to reposition samples if the automatic sampling selected a uniform area that is underexposed or overexposed and that
lacks information about grain structure.
Noise samples for the Match Grain and Remove Grain effects are always extracted from the source layer without
regarding any effects or masks already applied to the layer; this method results in more accurate sampling. If you want
the samples to include the existing effects, precompose or pre-render the source layer with the effects and then apply
the grain effect to the resulting source layer.
Avoid sample areas with the following characteristics: sharp edges, color gradients, highlights, textures such as grass
or water ripples, fine detail such as hair or tree leaves, and overexposed or underexposed areas lacking in information.
1 In the Effect Controls panel, choose Noise Samples from the Viewing Mode menu.
The samples appear as small white squares (24x24 pixels) overlaid on the source image.
Choose Manual from the Sample Selection pop-up menu in the Sampling controls group.
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3 To remove the least desirable samples from the image, try reducing the Number Of Samples value.
To move a noise sample, do one of the following:
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• Click the point parameter
in the composition, centered on that sample. Click the desired location in the Composition panel to place the
sample.
• Using the Selection tool , drag the sample point in the Composition panel to the desired location.
• Enter the desired horizontal and vertical coordinates in the Effect Controls panel.
Note: The number of sample points that are enabled corresponds to the current value of the Number Of Samples.
Repeat for each sample point you want to move.
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Change the sampling source frame
By default, the Remove Grain and Match Grain effects take noise samples from the first frame of the sequence, but you
can choose to sample the noise from a different frame. Changing the frame may be useful if large lighting or exposure
variations occur between frames within the sequence.
Decide which frame you want to sample; make sure that the project settings Display Style is set to Frames,
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numbering from zero. The number of the current frame then appears in blue in the upper-left corner of the
Timeline panel. Enter that frame number as the Source Frame value in the Sampling controls group.
2 Choose Noise Samples from the Viewing Mode menu.
The selected frame appears in the Composition panel, and its automatic samples appear on the image.
Change the noise sample box color
You can set the viewing mode for the Remove Grain or Match Grain effect to Noise Samples to see the areas sampled
by the effect. Sampled areas are automatically framed with a white outline. If you prefer, you can change the color of
these noise sample boxes.
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Next to the Sample Box Color control in the Sampling controls group, do one of the following:
• Click the color swatch, and select a color in the Color Picker.
• Click the eyedropper, and click a color anywhere in the application window.
for the noise sample in the Noise Sample Points controls group. A cross hair appears
USING AFTER EFFECTS CS4
Effects and animation presets
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