I might need a better image to start with, the blacks look really crushed on that preview.
I'll check out the linked image and see how it looks, they might not be as crushed as they look on the forum.
It might be a week or so before I can get to it, I am pretty snowed.
Check out Davinci Resolve 10 lite, it is completely free for anything up to UHD resolution, is available for OSX, Linux and Windows, and allows you much more control than most programs. The lite version is basically the complete version apart from resolutions above 3184x2160 and the ability to use more than one GPU.