Originally Posted by wiewiorcwaniak
Adding colour to shadows via color balance, am I right?
You might have to experiment with that one a bit. The appearance of saturation normally tapers off in deep shadows. Here it obviously doesn't, but some of that is propagated into the midtone values. The photo has some rather obvious vignetting, so you should take that into consideration. I think they were going for a retro look with that aspect. Lenses with large apertures would often vignette quite a bit when shot close to maximum aperture.
You can give color balance a try, but it's not always easy to control. I would try adjusting the endpoints in curves. I mean the ones normally set to 0. Bring 1 or 2 of them up to hit the desired color balance in your shadows. Even out the overall bias via the middle slider in levels.
Of course any of these tactics is going to require a lot of playing with it. If it isn't going in the right direction at all, you may have to revise your approach. Also you'll want to adjust your levels (or do something similar in curves) just a bit to ensure that your brightness range for shadows and highlights is similar to this image. You'll have an easier time visualizing the rest that way.