heh, i have absolutely no plans for that 
i want to understand more how the results are formed and which parameters are essential, then implement the grain and preflash etc (left out quite a few things now), and then get into perf optimisation.
and yes, negative rgb is just fine. negative spectral energy is not. the sigmoidal spectral upsampling table i created a few days ago will upsample everything, and it will even be meaningful inside spectral locus. outside it just uses inpainting to give you a positive spectrum close to the coordinate you requested.
glsl. i don’t really speak python and i absolutely hate it if software stacks up toolchains (like shellscript stuff in latex packages…).