Guided Blur (Refine Edge)

Guided Blur (Refine Edge)

The guided filter is an edge-preserving blur, useful to add details to the edges of a roto/matte using a second image as a guide.

For those who are familiar with Photoshop, the results are similar to the Refine Edge feature, improving fine detail around the edges.

Use cases

• Improving edge detail from roto/mattes, especially with difficult to capture details like hair or fur.

• Keying: blurring a core matte can lead to blobs/webbing around corners and small details. Blurring using the guided filter alleviates this problem.

How to use

• Connect the alpha/roto to the matte input and a RGB image which we will extract the details, usually the original plate, to the img input.
• Control the amount of detail using the edge detail slider.

Values close to 0 makes the filter behave like a regular blur.
Values higher than 6 are usually too high, identifying grain as edges and introducing artifacts.
Recommended values are between 2 and 5.

Release Notes

1.3

• Speed-up the gizmo by 30%
• Now compatible with Nuke 8

1.2

• Fixed error 'unknown command' when loading the gizmo using the function Other > All plugins > Update.

1.1

• Switched the image and input nodes, so it behaves more predictably when disabling the gizmo.
• Fixed error when using the gizmo with OCIO profiles

Credits

The filter was implemented following the technique proposed in the paper:
He, Kaiming, Jian Sun, and Xiaoou Tang. 'Guided image filtering.' In European conference on computer vision, pp. 1-14. Springer, Berlin, Heidelberg, 2010. kaiminghe.com/eccv10/

Questions or bugs,feel free to shoot me an email:
Rafael Silva - www.rafael.ai