Skull registration with rotational offset.

Technique: mutual information (MI) based metric with stochastic gradient ascent
using sparsely sampled histograms for probability density estimation.

Experiment:Rotational offset of 15 degrees in pitch.

Goal Projection Image -- View 1 (sagittal) Goal Projection Image -- View 2 (coronal)
Offset Projection Image -- View 1 (sagittal) Offset Projection Image -- View 2 (coronal)

Skull registration animation.