What are deflicker algorithms used to deflicker stills that should be composed to a timelapse movie?
(Flickering caused by shutterspeed adjustments in sunset/sunrise shots...)
I have no idea what algorithms commercial software uses for this task, but I'll happily make one up for you:
Do this independently for all colour channels and you'll also smooth any changes in colour.
If you like programing, I found a link to a python project that will do exactly what you want. It will also interpolate between frames if you are missing a couple.