1. A method of separating tissue classes in magnetic resonance images, the method comprising: acquiring a plurality of magnetic resonance images of a subject with different acquisition parameters; generating a multi-dimensional intensity distribution model from the plurality of magnetic resonance images, the multi-dimensional intensity distribution model representing a distribution of intensities of voxels in each magnetic resonance image of the plurality; identifying clusters of correlated intensities in the multi-dimensional intensity distribution model; and assigning the clusters into one or more tissue classes based on the correlated intensities of each of the clusters.