MRI scans typically have higher resolution within a slice than between slices.
To improve the resolution, two MRI scans are taken in different, preferably orthogonal,
directions. The scans are registered by maximizing a correlation between their
gradients and then fused to form a high-resolution image. Multiple receiving coils
can be used. When the images are multispectral, the number of spectral bands is
reduced by transformation of the spectral bands in order of image contrast and
using the transformed spectral bands with the highest contrast.