This morning I also quickly tried to add some fake halation effect (light bleeding into darker areas).
It's basically a highpass filter using the bloom downsamples and the current scene color texture, and then isolating the bright parts to make them bleed into the dark areas.
Currently it's an additive blend done with the HDR color, so it adds light. It low enough to no matter too much. Maybe I should use a lerp too to be more energy preserving ?