I am using mask for motion tracking scene, and I want use blur for mask in compositing. what is problem: blender node is bluring mask and make it larger, that causes problem for me, is it possible to make blur inside region of mask? ( blured mask, but in mask area, not outside) Last image has red area, that shows how blur node make mask larger Thanks MASK original


BLured are is RED


  • 2
    $\begingroup$ Erode and blur? $\endgroup$ – lemon Aug 15 '19 at 7:30
  • $\begingroup$ Thanks, good node $\endgroup$ – Vlad Markelov Aug 15 '19 at 8:21
  • $\begingroup$ Just multiply the mask by the resulting blur. Done. $\endgroup$ – troy_s Sep 15 '19 at 23:14

Just use a Dilate/Erode node set to 'Feather' instead of a Blur. Setting a negative Distance will erode the edges based on the set Falloff - so it will always be within the region of the mask. For more control of the falloff, set the Falloff of the Dilate/Erode to Linear and add a Color Ramp node or similar so you can control the falloff profile manually.

composite dilate/erode feather

Note the Split Viewer showing the comparison in the Image Viewer window between original (right-hand side) and 'feathered' (left-hand side).

  • $\begingroup$ Thanks a lot, erode node looks like good solution. Falloff node only available in shader compose, can't use for mask, but erode and color ramp is enough. $\endgroup$ – Vlad Markelov Aug 15 '19 at 8:21
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    $\begingroup$ @VladMarkelov by ‘falloff’ I meant the Falloff property of the Dilate/Erode node, rather than the Falloff node. Glad this helps. $\endgroup$ – Rich Sedman Aug 15 '19 at 9:50
  • $\begingroup$ understood about falloff, thanks) $\endgroup$ – Vlad Markelov Aug 16 '19 at 15:34

Perform your blur, then apply the emission constriction by multiplying the mask by the result.


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