Exponential bloom#591

I love the addition of the bloom effect, but I’d really like it if the bloom were revised to use exponential falloff, which is common in render engines, compositing and games and is more accurate to how light actually behaves. I understand not wanting to overwhelm users with too many parameters, so these could be handled behind the scenes, but exponential/layered bloom relies on a small and sharp inner core and a soft and large falloff so that it correctly handles detail and gives the effect of glow rather than a foggy lens. I’ve attached a screenshot of Blender’s bloom (“Glare” node) to deemonstrate this: you can see that you can’t really tell exactly where the bloom stops as it falls off gradually, even at a small size, and it really convincingly creates a glowing effect. While this is common in compositing tools and game engines, most photo editing tools I’ve seen neglect this detail and use a simple single Gaussian blur implementation, so I’d love if Darkroom could actually do this properly.

As for size: it would certainly be nice to have a size control in this case, but I don’t really know how this could be reconciled with how the UI is currently laid out where most settings are just a single slider rather than offering “sub-options”. Perhaps it could scale with strength? Single sliders are fine for options that inherently won’t have sub-options like exposure, but I feel like they’re ultimately not entirely sufficient for more “opinionated” and complex effects like bloom…