Compositing Problems

[RayPerspectives]

Hi,

I am desperatly trying to composit something here, but cannot get it to look realistic. I want to edit a somewhat blurred red flag into a dark blue sky, but in the areas of mixed alpha/partial transparency I get these dark borders which make it look absolutly unrealistic. Makes sense because red and blue mixed together result in some purple color which ends up being darker, but can I prevent that somehow?

Here you can see a picture that visualizes my problem.

[D Fosse · Accepted solution]

This is one of those instances where you might want to go into Color Settings and check "Blend RGB colors using gamma":

Note that this will only work if you have them on separate layers so that they are actually blending. If you do it in a single layer it will all blend in the document color space, as it does when unchecked.

Unchecked is the default and you should normally keep it as such.

[RayPerspectives]

Omg thank you soo much this is what I spent hours searching for!!

[D Fosse]

You can also do it in Lab, and here even in a single layer. But for some reason I don't think it looks quite as good there, the transition looks a bit dirtier. I don't know why.