I would like to paint a layer mask over a photo with blurred edges in some areas but hard edges in others (basically where the mask matches the subject's silhouette and a blurred layer mask creates a weird effect)

So far, the method I have is

  1. create a closed path
  2. duplicate it and remove the segments where I don't want a blur
  3. fill the closed path with white
  4. do ... something? with the second path

The obvious thing would be to stroke the duplicated path with the Convolve tool, but it doesn't blur anywhere near as much as I want it to, even with spacing set to 1.0

I've also tried using a 50% grey brush but no matter what settings I use I get a thick grey line that looks weird when used as a layer mask, I've tried hardness set to 0.0 and spacing set as high as possible without causing artifacts.

Here's an example image of what I'm talking about, on the left is the original filled path, then a section with the Convolve tool that looks good but is too narrow, and finally on the right with the Paintbrush that is the right width but looks terrible.

enter image description here

What's the right thing to do here? Thanks!

1 Answer 1


In the next image I have a layer filled with a gradient and an elliptical layer mask:

enter image description here

To make a part of the layer mask edge fuzzy I started by making a selection which covers that part of the layer mask which should have fuzzy border. The selection is a rectangle. Also the mask in the layers panel is selected to aim the drawn selection to the mask, not to the image:

enter image description here

You can draw the selection as a path if you want fine control. Convert it to a selection after the path is edited to good enough.

Gaussian blur makes the selected area of the mask fuzzy:

enter image description here

  • Ah, so using a new path to just affect the areas I want to blur, that makes sense. So is there no way to configure a brush to do the blending effect I was after? That would mean I could keep using the same path for generating the layer mask and for blurring it.
    – rophl
    Jun 21, 2022 at 9:57
  • Illustrator users have it. They can put a gradient along a path. In GIMP you could in theory stroke a path with custom brush which creates a gradient transversally to the path. Making the brush angle to follow the path direction is tricky - I have never succeeded to make it happen properly, so I didn't recommend it. Test, If you find how to do it.
    – user82991
    Jun 21, 2022 at 10:25
  • Fair enough, I guess I hadn't thought of how it would need to handle direction. As a slightly different approach, is it possible to modify the convolve tool to allow rates higher than 1.00?
    – rophl
    Jun 21, 2022 at 10:43

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