How do I create a gradient map from an image? [solved]

[Ofnuts]

With the process expounded above:
Starting with this:

   

Mapped with an ugly Blue-Red-Green gradient. The only constraint is that the Red middle color has a "Value" (in HSV) around 50, while Blue is closer to 0 and Green closer to 100 (because this kind of gradient-mapping normally preserves the luminosity curve)

   

Using the process, recover a gradient:

   

Apply the gradient again:

   

So the technique works decently, the trouble here is that the picture chosen has a lot of dark pixels, so the palette has more dark colors. On a more balanced image results ought to be better.