Adobe After Effects - Manual (Page 601)

Note:
Intensity
Channel Intensities
Size
Channel Size
Softness
Aspect Ratio
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a Blending Mode in the Application controls group.
To define how much grain is added to each tonal area in your image and the midpoint, adjust the Shadows, Midtones, Highlights, and
Midpoint values in the Application controls group.
To animate the added grain, adjust the properties in the Animation controls group.
To apply the effect to the entire image, choose Final Output from the Viewing Mode menu.
Tweaking controls for Grain effects
The Match Grain and Add Grain effects share a group of Tweaking controls. You can use these controls to modify the intensity and size of the
noise and to introduce a blur, all of which can be done across the three channels or individually for each channel. You can also change the aspect
ratio of the applied grain.
The values of the Tweaking controls are relative to the noise sampled in the source layer: a value of 1.0 leaves that property of the source
noise unchanged, while higher and lower values alter the applied noise.
Adjust any of the following controls in the Tweaking controls group:
Controls the amount of variation in brightness and color strength between pixels in the generated noise, which determines the visibility of
the noise. Increasing the value does not change the position or size of each grain but makes the grain appear to pop more; lower values give a
more subtle muted appearance.
Controls the contrast between pixels in the generated noise separately for each channel. For example, you may want to add
more grain to the blue channel to emulate film.
Adjusts the size of the generated grain in pixels.
Adjusts the size of the generated grain in pixels independently for each channel.
Sets the amount of softness in the grain.
Controls the ratio of the width of the generated grain over a constant height of 1; this setting is useful for emulating the effect of
anamorphic lenses or for aesthetic effects. A value higher than 1 stretches the grain horizontally; values smaller than 1 squash it horizontally.
Dust & Scratches effect
The Dust & Scratches effect reduces noise and defects by changing dissimilar pixels within a specified radius to be more like their neighboring
pixels. To achieve a balance between sharpness of the image and hiding defects, try various combinations of Radius and Threshold settings.
This effect works with 8-bpc and 16-bpc color.
Original image with scratches (upper-left), enlarged view of scratches (lower-left), and scratches removed with loss of clarity (lower-right)
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