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Noise in Render with Alpha

Posted: Sun Apr 08, 2018 10:49 pm
by 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:
Image


I have attached a minimal file which reproduces the issue.

Thanks! :)

Sam

Re: Noise in Render with Alpha

Posted: Mon Apr 09, 2018 7:41 am
by 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.

Re: Noise in Render with Alpha

Posted: Mon Apr 09, 2018 6:25 pm
by sdhains
perfect, that worked. Thanks a lot!