Bug? Blur node blends pixels with white instead of transparency?

Hi folks!

I’m working on a project where I’m blending an image that is set on transparency. The non-transparent pixels are not near the edges of the bitmap.

It seems to me that when the Blur node (I’m using Gaussian) is blending transparent pixels with partly opaque pixels, it is using something like white instead of transparency?

View the attached image at full size in order to see the comparison.

It might seem minor, but it caused a bit of hair-pulling for my project, due to the difference.
I’m trying to think of a workaround, but I can’t think of a way.


Can you send us a composition that exhibits that behavior? We haven’t reproduced what you are seeing.

OK, seems this one was my mistake, due to a compositing mistake after a bunch of testing. Compositing modes are complicated!

There is a difference between the Sketch gaussian blur and the Vuo one, resulting in a slightly different distribution around the edge of opaque pixels. Apparent when Diff’ing two files that have had the same effect., one from Sketch one from Vuo. That’s not a problem, per se, but I’ll note it here for history.

As always, thanks!!