Grain
The Grain node lets you add synthetic grain (rather than grain derived from actual film stock) to an image. This helps you ensure that all of the elements in your composite, including those which were digitally generated, look like they were shot on the same film stock.
The presets dropdown menu includes predefined types of grain, such as Kodak 5248 and Kodak 5218. These are the correct size for 2K scans.
You can also adjust the Grain node’s controls to match a sample piece of grain:
1. | Find a sample with a rather constant background. |
2. | Blur the sample to remove the grain. |
3. | Connect the blurred sample to the Grain node’s input. |
4. | In the Viewer, wipe between the Grain node and the original sample image, and adjust the Grain node’s controls to match the grain. It helps to view and match each of the red, green, and blue channels separately. |
See also ScannedGrain and F_ReGrain.
Inputs and Controls
Connection Type |
Connection Name |
Function |
Input |
1 |
The image sequence to receive the effect. |
Control (UI) |
Knob (Scripting) |
Default Value |
Function |
User Tab |
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seed |
seed |
134 |
A different grain pattern is produced for each frame. Change this number to get a different initial pattern, for instance if you are using multiple Grain nodes. If you require an identical grain plate for every frame, enter -frame in this field. |
presets |
presets |
N/A |
Choose the film stock you want to match: • Kodak 5248 • Kodak 5279 • Kodak FX214 • Kodak GT5274 • Kodak 5217 • Kodak 5218 • other - changes the label on the node to other. This has no effect on the effect applied. |
Size |
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red |
red_size |
3.3 |
Shrinks or enlarges the effect in the red channel. |
green |
green_size |
2.9 |
Shrinks or enlarges the effect in the green channel. |
blue |
blue_size |
2.5 |
Shrinks or enlarges the effect in the blue channel. |
Irregularity |
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red |
red_i |
0.6 |
Increases or decreases the random quality of the effect in the red channel. |
green |
green_i |
0.6 |
Increases or decreases the random quality of the effect in the green channel. |
blue |
blue_i |
0.6 |
Increases or decreases the random quality of the effect in the blue channel. |
Intensity |
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red |
red_m |
0.416 |
Increases or decreases the contrast of the effect in the red channel against the original image. |
green |
green_m |
0.46 |
Increases or decreases the contrast of the effect in the green channel against the original image. |
blue |
blue_m |
0.85 |
Increases or decreases the contrast of the effect in the blue channel against the original image. |
black |
black |
0 |
The base amount of grain to add at the black point. |
minimum rgb |
minimum |
0, 0, 0 |
The minimum output rgb values. If the calculation results in pixel values lower than these, these values are used instead. |
Mask |
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Apply only through alpha |
maskgrain |
enabled |
When enabled, effect is limited to the non-black areas of the image’s alpha channel. This can be useful when you want to apply grain to premultiplied CG images without contaminating the background black. When disabled, effect is applied to the entire image. |
Invert alpha |
invert_mask |
disabled |
Inverts the use of the alpha channel, so that when Apply only through alpha is enabled, the effect is limited to the non-white areas of the alpha. |