To Compensate For Existing Noise When Matching Noise; Adding Grain Or Visual Noise To An Image - Adobe AFTER EFFECTS 7.0 Manual

Shows the current color matte or mask, or the combination of both, which results from the current
Blending Matte
settings of the Blend With Original controls group.
Renders the full active frame, using the current settings of the effect.
Final Output
8 Animate the added grain, if desired.
Choose Final Output from the Viewing Mode control.
9

To 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, simply 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. This makes the Compen-
sation Sample Points available for manual repositioning.
Apply the Match Grain effect to the destination layer.
1
in the Effect Controls panel, adjust the Compensate For Existing Noise value under the Match Grain effect as
2
needed. The noise in the source layer and the noise in the destination layer are sampled, and their difference is calcu-
lated, so that only enough noise to match the destination layer to the source layer is applied to the destination.
To modify the noise samples, choose Noise Samples from the Viewing Mode menu, change the Sampling >
3
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 a Compensation Sample Point's point parameter
want to move the point in the Composition panel.
Choose Final Output from the Viewing Mode control.
5

Adding grain or visual noise to an image

The Add Grain effect generates new noise from nothing and does not take samples from existing noise. Instead, a
number of parameters and presets for different types of film can be used to synthesize many different types of noise
or grain. You can modify virtually every characteristic of this noise, control its color, apply it to the image in several
ways, even animate it or apply it selectively to only a part of your image.
The distribution of the added noise over the color channels does affect the overall color of the resulting image. With
a dark background, the noise tends to add to the image visually, so a red tint or more noise in the red channel gives
a reddish hue to the image. With a bright background, the noise tends to subtract from the image visually, so a red
tint or more noise in the red channel gives a cyan color. The result also depends on the Blending Mode control in the
Application controls group.
in the Effect Controls panel, and then click where you
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User Guide