How to properly render emissive and transparent materials (fire) for compositing I am rendering a fire to a multilayer EXR and then composite it using the method described in this answer ontop of my footage.
One comment states that it is difficult to work with my EXR because I only have a beauty pass and my emissions and transparency aren't separated. I also get all sorts of wired effects compositing my exr when I try to pre divide/post multiply. But if I do not do that everything tourns with.



Here it gets blocky
Nothing I was just trying to bring the highlights of the fire a bit down but it messed the image up so I pressed premultiply / post divide and then it messed the rest up. I am wondering how blender outputs the exr is it already premultiplied or is it straight?
Reference files:
https://drive.google.com/drive/folders/1HatjWYAmmXHfEiaTNYChJYBK0PZVvMo7?usp=sharing
As @troy_s stated in this case a normal alpha over should be used. In Resolve, this translates to a merge node with the Alpha Gain turned to 0.