Blending And Adjusting The Color Of Added Or Matched Grain; Working With Noise Samples In Grain Effects - Adobe AFTER EFFECTS 7.0 Manual

Blending and adjusting the color of added or matched grain

You can adjust the color, saturation, and blending behavior of the grain that is generated by the Add Grain or Match
Grain effect to suit your needs.
Several factors can affect the apparent color of the grain that these effects generate, including the following:
•
The color value of the underlying pixel in the source image.
•
The Saturation value of the noise.
•
The Tint Color and Tint Amount values, if you have modified these from the defaults.
•
The Blending Mode value in the Application controls group.
•
The amount of noise applied, if any, to each channel individually using the Channel Intensities controls group.
Using the Color controls group in the Effect Controls panel, you can adjust any of the following:
Gives the added noise a single tint. By default, the tones are black and white, but you can change the
Monochromatic
Tint Color to make it a gradient of any color. (The Saturation and Channel Intensities controls aren't available when
Monochromatic is selected.)
Controls the depth and intensity of the color shift.
Tint Amount
Controls the color the added noise shifts toward.
Tint Color
Controls the amount and vividness of the color.
Saturation
The Blending Mode in the Application controls determines how the color value of the generated noise combines with
the color value of the underlying source layer at each pixel:
Makes the generated grain appear embedded in the image. This mode affects darker colors more than lighter
Film
ones, just as the grain in a film negative appears.
Simply multiplies the color values of the noise and the source. However the result may be either lighter or
Multiply
darker than the original, because the noise may have either a positive or negative value.
Combines the color values of the pixel in the source with the noise. However, the result is not always lighter
Add
than the original because the noise that is created by grain effects can have either a positive or negative value.
Multiplies the inverse brightness values of the noise and the source. The effect is like printing from a multiple
Screen
exposure on a negative. The result is always brighter than the original.
Combines the behavior of Film and Multiply: Both shadows and highlights get less grain, while midtones
Overlay
get a full application of grain.

Working with noise samples in grain effects

Noise sampling is the first and most important step in removing noise from an image or in matching the noise of one
image in another image. Normally, this process is entirely automatic. For very fine control, you can switch to Manual
mode and adjust the samples yourself using the Sampling controls group in the Effect Controls panel.
A noise sample should be a solid block of uniform color that clearly displays the noise pattern present in the image.
The object is to extract samples of pure noise, without any image features that the algorithm could misconstrue as
grain. For instance, extract samples from a piece of sky, a background wall, or an area of fleshtone. All samples should
be selected from the normal range of the film, DV, or video stock. Avoid underexposed or overexposed areas lacking
in information, especially areas where pixel values have been clipped to pure black or white. Within this normal
exposure range, it is best to select samples with various RGB values and colors, for instance one sample from a bright
area, one from a dark area, and one from the midtones.
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User Guide