User Manual

Time Lock
Enabling Time Lock stops the random seed from generating new grain on every frame.
Monochrome
When the Monochrome checkbox is enabled (default), the grain is applied to the red, green,
and blue color channels of the image equally. When deselected, individual control over the
Size, Strength, and Roughness of the grain in each channel becomes possible.
Lock Size X/Y
Deselect the Lock Size X/Y checkbox to control the size of the grain along the X- and Y-axis
individually.
Size
The grain size is calculated relative to the size of a pixel. Consequently, changing the resolution
of the image does not impact the relative appearance of the grain. The default grain size of 1.0
produces grain kernels that cover roughly 2 pixels.
Strength
Grain is expressed as a variation from the original color of a pixel. The stronger the grain’s
strength, the wider the possible variation from the original pixel value. For example, given a
pixel with an original value of p, and a Grain node with complexity = 1 size = 1; roughness = 0; log
processing = off; the grain produces an output value of p +/- strength. In other words, a pixel
with a value of 0.5 with a grain strength of 0.02 could end up with a final value between
0.48 and 0.52.
Once again, that’s a slight oversimplification, especially when the complexity exceeds 1.
Enabling the Log Processing checkbox also causes that variation to be affected such that there
is less variation in the blacks and more variation in the whites of the image.
NOTE: When visualizing the effect of the grain on the image, the more mathematically
inclined may find it helps to picture a sine wave, where each lobe of the sine wave
covers 1 pixel when the Grain Size is 1.0. The Grain Size controls the frequency of the
sine wave, while the Grain Strength controls its amplitude. Again, this is something of
an oversimplification.
Roughness
The Roughness slider applies low frequency variation to give the impression of clumping in the
grain. Try setting the roughness to 0, and observe that the grain produced has a very even
luminance variation across the whole image. Increase the roughness to 1.0 and observe the
presence of “cellular” differences in the luminance variation.
Offset
The Offset control helps to match the intensity of the grain in the deep blacks by offsetting the
values before the intensity (strength) of the grain is calculated. So an offset of 0.1 would cause a
pixel with a value of 0.1 to receive grain as if its value was 0.2.
Common Controls
Settings Tab
The Settings tab controls are common to all Film nodes, so their descriptions can be found in
“The Common Controls” section at the end of this chapter.
Chapter – 90 Film Nodes 2021