This looks like an unpremultiply error. The edge pixels are getting divided by the values coming from the gmask as if they had been multiplied by the matte. If they haven’t been multiplied by the matte then there is no need to do the unpremultiply (divide).
Are you doing the comp in batch? Using an action node or a comp node. Can you share a grab of you schematic?
I suspect you are using action. Most unpremultiply techniques are quite explicit. Action is a little hidden away inside of the surface settings.
Select the layer inside the Action schematic.
Go to the Surface menu.
Look for the Blending column or the Alpha settings (not in front of the box atm)
You can toggle the setting between Premultiplied and Unpremultiplied (or “Straight”). If you are getting dark or white edges, ensure this is set correctly to match your source material.
If you can rule out premultiplication errors, then I would attribute this to a known bug that can present similarly. It can usually be resolved by pre-rendering your mask.
Ah… that makes sense. Googling how to pre-render a mask… Thank you!
So… Surface 3 was a remnant of a previous thing that I did and I hadn’t deleted it yet. It isn’t doing anything and I’ve deleted it to no effect.
Surface 2 is the front of the basket that is rotoed out to cover the dog that we’re adding into the shot.
So this might help two birds and one stone- I would do that restore roto (surface 2) outside of the action in just a gmask tracer. Gmasks in action slow you down and with your selective and stuff happening in there I wouldn’t be surprised if somehow that’s busting some premult thing.
I’m not here to tell anyone how to comp, Flame is very flexible, me personally, I’d go about it something like this though. The part that really might help though is the BasketRestore happening outside of action. So the order being, BG Plate, Dog, Basket over top )the comp action is just layering things, only premultiplied surface is the dog). I 100% don’t want to sound condescending by the way!! Just a thought about things happening in action or outside, totally personal preference though!
Thank you for the awesome tip! I can definitley see how this workflow would optimize a lot of what’s going on.
