Using machine learning to colourise grayscale images, is it being done? Options

[Habukaz]

I am just wondering whether machine learning is being used (by people here or elsewhere) to colourise space images that lack colour data (like MER Navcam images, LORRI images and so on).

I have a few ideas on how to do it; but if it is already routinely being done (and with good results), it wouldn't be as cool to try to implement them.