Adobe After Effects - Manual (Page 606)

Compensation Samples
Preview
Blending Matte
Final Output
To the top
in the Composition panel, with its noise sample squares displayed.
Shows the noise samples that have been automatically extracted from the destination image.
Displays the current settings of the applied effect in a 200x200 pixel area.
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.
Renders the full active frame, using the current settings of the effect.
8. Animate the added grain, if desired.
9. Choose Final Output from the Viewing Mode control.
Compensate for existing noise when matching noise
If you’re trying to match the grain between images with the Match Grain effect, and your destination layer already has its own visible grain, a grain
mismatch or grain build-up may occur. To prevent these problems, the Compensate For Existing Noise control extracts a noise model from both
the source and the destination and then modifies the noise from the source to account for the noise already present in the destination, before
applying it to the destination.
To use this control automatically, set the Compensate For Existing Noise slider to 100%. You can then view the noise samples in the destination
layer by choosing Compensation Samples in the Viewing Mode menu. You can also reposition the samples in the destination image by setting
Sampling Mode to Manual, which makes the Compensation Sample Points available for manual repositioning.
1. Apply the Match Grain effect to the destination layer.
2. In the Effect Controls panel, adjust the Compensate For Existing Noise value under the Match Grain effect as needed. The noise in the
source layer and the noise in the destination layer are sampled, and their difference is calculated, so that only enough noise to match the
destination layer to the source layer is applied to the destination.
3. To modify the noise samples, choose Noise Samples from the Viewing Mode menu, change the Sampling > Sample Selection control to
Manual, and then expand the Compensation Sample Points. The current value of Number Of Samples determines how many points are
available.
4. To reposition each sample point, do any of the following:
Drag each sample point in the Composition panel to a new location.
Enter new x and y coordinates adjacent to the sample point under the Compensation Sample Points controls in the Effect Controls panel.
Click the point parameter for the Compensation Sample Point in the Effect Controls panel, and then click where you want to move
the point in the Composition panel.
5. Choose Final Output from the Viewing Mode control.
Median effect
The Median effect replaces each pixel with a pixel that has the median color value of neighboring pixels with the specified Radius. At low Radius
values, this effect is useful for reducing some types of noise. At higher Radius values, this effect gives an image a painterly appearance.
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