This is just totally a thought I had and would be really cool. If it's possible, I'd sure love it for doing alien bodies. Basically just an atmosphere mixer that uses main atmospheric gasses as their components. Sliders to essentially set the amount of gas of a certain type in the atmosphere, and than the simulation gets all it's colours from light based on real world properties of colour changes. So you could get relatively accurate atmospheres by plugging in the values for Mars's atmospheric makeup, or design one yourself.
I think that could not be definitive yet because even though for instance we know the primary constituents in Jupiter's atmosphere, the chemical cause of the colorations is debatable. Many common compounds have associated colors so if you had those constituents for an exoplanet you could have a starting point from which to select colors. Cheers
We know exactly why Jupiter is coloured the way it is. We use mass spectrum wavelengths to detect elements. These colours are from phosphorus, sulfur, and hydrocarbons being pulled from the core mixing arbitrarily with clouds, which colours then.
Atmospheric coloring is a totally different subject than colouring a cloud. We already have custom color controls with direct and ambient light for setting colors for different gasses, but with the way decay colours work in atmosphere you can't just quickly make for instance a mars atmosphere. It's just not possible with a single atmosphere.
We'd need a simulation for direct and ambient lighting in atmospheres that can correctly model these colours based on basic gas mixes.