Noise in Render with Alpha

[sdhains]

Hey Forum!

Simple question here, that I'm sure many have encountered and solved:

I can't figure out why when I include the alpha channel in my render, that I get this coloured noise around the edges of the render!

Why is this happening? How can I remove it?


here is the noise in the render:



I have attached a minimal file which reproduces the issue.

Thanks!

Sam

[fantome]

i think it is because you are watching an unpremultiply image.
this mean that if you don't want to see that noise you have to check the pre-multiplied alpha image option in your render target settings.
with that option check R G B channel will be multiply by Alpha, and thus giving a smooth aliasing.

[sdhains]

perfect, that worked. Thanks a lot!