Gripes about the BLUR brush

Paint/Blur brush samples colors outside of the brush.
Why is that a problem -
When I paint close to an edge, the blur brush will pull in colors from the adjacent area, even though the brush itself stays inside the edge. It creates a smear of the adjacent colors along the edge.
Masking the brush doesn’t help, the mask works for the brush itself, but the mask is ignored for which pixels are sampled for the blurring.

Most of the brushes operate on a known quantity - blur will process the underlying image to the radius you select and then paint through to it, regardless of how many times you go over the same area. Depending on what you want to do, you can get partially the way there by setting the opacity pretty low, the softness high, and turning on Buildup. This will let you brush in more of the middle area of the blur.

Sounds like what you want is a sample-based blur, similar to what Drag does.

Hi Paul,
I haven’t really found a way to deal with the smudge issue. It has giving me some grief, there isn’t really a way that I can see of applying blur brush to an area close to a high contrast edge.
The way the blur brush works, like you said, the entire underlying image is blurred and then the brush paints it through. However I’d like to suggest only the area within the brush should be blurred, excluding the area around it, as well as the mask.
I have a demo pic to demonstrate the issue, but don’t see how to attach it here.

You can copy/paste images into your message.

There is a single blur stroke in the black area. It shows how the white area to the left creates the unwanted smudge effect.

I’ll investigate adding a sample-based blur which will work more like how Photoshop does it.