Removing Grain from a Clip

Pre-processing > Adding and Removing Film Grain >

Use the DeGrain command to remove grain from a clip. DeGrain applies a noise reduction algorithm that consists of two filters:

An RGB-averaging filter that removes noise and softens the image.
An RGB-sharpening filter that adaptively restores the sharp details of an image.

When you remove grain from a clip, you start with the default values for these filters and adjust them to produce the degrained result that you need.

Because grain varies according to film stock, lighting conditions, colour, and resolution, it is advisable to create a DeGrain setup for each clip from which you want to remove grain.

To access DeGrain from the Desktop:

From the Main menu, click Processing, then click DeGrain.
Select the clip from which you want to remove grain, and then select a destination reel.
The DeGrain menu appears.

(a) View box (b) Render Method box
Optional: Click Reset All, and then Confirm, to reset DeGrain to the default settings.
By default, the result clip appears. You can also view the front clip by selecting Front from the View box.
To view the front and result clips simultaneously, and to speed up interactivity while defining the DeGrain parameters, enable the Crop button and use the crop box. See Defining the DeGrain and ReGrain Area.

To access DeGrain from Batch:

Drag a DeGrain node to the Batch desktop.
Parent the output from which you want to remove grain to the front clip input socket of the DeGrain node.
Select the DeGrain node.
The DeGrain menu appears.

(a) View box (b) Render Method box
Press Alt+2 to select the 2-Up viewport layout.
With the viewport on the left set to display the front clip and the viewport on the right set to display the result clip, you can better track the effects of your changes against the front clip.
You can also use the crop box to view the front and results clips simultaneously, and to speed up interactivity. See Defining the DeGrain and ReGrain Area.
Use the reference buffer to store intermediate results as you set the grain removal parameters. See Storing Reference Frames in the Reference Buffer.

To remove grain from a clip:

Select an option from the Render Method box.

Select:	To:
Progressive	Remove grain from frame-based material, including film-based material transferred either to PAL without field interpolation, or to 30 fps field-based formats, provided 2:3 sequence has been removed.
Interlaced	Remove grain from field-based video, thus compensating for temporal jitter between fields in each frame.

Enable View.
In the View menu, use the R, G, and B buttons to control the display of the corresponding channels in the image window. You can also use the corresponding hot keys (Shift+R, Shift+G, or Shift+B) in the DeGrain menu. Enable Excl and then click R, G, or B to view each channel exclusively as a greyscale representation. You can also use the Shift+X hot key combination in the DeGrain menu to enable Excl. Use Shift+Z to restore the RGB view.

(a) Channel Display buttons (b) Exclusive button
Set the RGB Average Blur radius to remove the grain from the clip:
- Enable Proportional and drag the sliders in the RGB Average group to average RGB globally. This is usually a good initial step.
- Disable Proportional and adjust the R, G, and B sliders independently. Because film grain is not usually uniform through the R, G, and B channels, this is often a required step for fine-tuning the RGB Average.
(a) RGB Average Blur controls (b) RGB Adaptive Sharpness controls
Set the RGB Adaptive Sharpness radius to restore sharpness where it is needed:
- Enable Proportional and drag the sliders in the RGB Sharpness group to set RGB sharpness globally.
- Disable Proportional and adjust the R, G, and B sliders independently.
When you are satisfied with the result, click Process to remove grain from the clip or continue building your processing pipeline, if you are in Batch.

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