I plotted points from my Windows data and interpolated a curve using the Interpolate function of WolframAlpha. Interpolating all 22 points from the Windows data presented me with a too complicated curve, so I left there only 6 points (every 4th point), and got the curve from that. You could also use Wolfram Mathematica to approximate the curve using Interpolate with a small InterpolationOrder, so the resulting function would be an approximation of the data.
When I got the curve, I adjusted it so the value at x=0 was 0 and the value at x=64 was 1600 (my maximum for my 4530s display).
Using this method I got this function (and points):
goo.gl/5xsM3W. I'm using it now and the steps are mostly even, really better than before. It could use some minor adjustments here and there, but it is far from necessary.