C_Blur

C_Blur allows you to apply blur to a latlong image and produce a sensible result across the entire frame, as if it were applied to a rectilinear image all around.

Adds blur to an image or matte using Box or Gaussian filter algorithms. The blur value is calculated for image pixels by examining their neighbors within the constraints of the size control (in pixels), and applying the selected algorithms. The default, Gaussian, produces the smoothest blur, but takes longer to render.

Inputs and Controls

Connection Type	Connection Name	Function
Input	source	The image sequence to blur.
mask	An optional image to use as a mask. By default, the blur effect is limited to the non-black areas of the mask. At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Connection Type

Connection Name

Function

Input

source

The image sequence to blur.

mask

An optional image to use as a mask. By default, the blur effect is limited to the non-black areas of the mask.

At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Control (UI)	Knob (Scripting)	Default Value	Function
C_Blur Tab
Local GPU	gpuName	N/A	Displays the GPU used for rendering when Use GPU if available is enabled. Local GPU displays Not available when: • Use CPU is selected as the GPU device in the Preferences. • no suitable GPU was found on your system. • it was not possible to create a context for processing on the selected GPU, such as when there is not enough free memory available on the GPU. You can select a different GPU device, if available, by navigating to the Preferences and selecting an alternative from the GPU Device dropdown. Note: Selecting a different GPU requires you to restart Nuke before the change takes effect.
Use GPU if available	useGPUIfAvailable	enabled	When enabled, rendering occurs on the Local GPU specified, if available, rather than the CPU. Note: Enabling this option with no local GPU allows the script to run on the GPU whenever the script is opened on a machine that does have a GPU available. You should also select this if you wish to render from the command line with the --gpu option. See Nuke 14 Release Notes for more information on the GPUs Nuke supports.
Channels	channels	rgb	The blur effect is only applied to these channels. If you set this to something other than all or none, you can use the checkboxes on the right to select individual channels.
Size	size	1	Sets the radius within which pixels are compared to calculate the blur. Higher values widen the compare area, producing more blur.
Filter	filter	gaussian	Select the filter algorithm to use: • Box • Triangle • Quadratic • Gaussian Note: Box blur is the fastest to render, whereas Gaussian blur is the smoothest.
Bilinear	bilinear	disabled	When enabled, the final smoothness of the blur is improved, but the processing time increases.
Accuracy	accuracy	1	Controls the trade off between faster processing time at lower values, and smoothness at higher values.
Prescale	factor	1	Sets the downscaling factor applied before filtering. Lower values decrease render times, but at the cost of image quality.
mask	N/A	disabled	Enables the associated mask channel to the right. Disabling this checkbox is the same as setting the channel to none.
mask	mask	none	The channel to use as a mask. By default, the filter effect is limited to the non-black areas of this channel.
inject	inject	disabled	Copies the mask input to the predefined mask.a channel. Injecting the mask allows you to use the same mask further downstream.
invert	invert_mask	disabled	Inverts the use of the mask channel so that the filter effect is limited to the non-white areas of the mask.
fringe	fringe	disabled	When enabled, only apply the effect to the edge of the mask. When disabled, the effect is applied to the entire mask.
mix	mix	1	Dissolves between the original image at 0 and the full blur effect at 1.