Emmanuel Caruyer

Create mask of white matter, as well as a mask for each bundle.

Seems like white matter attenuation (as well as diffusion-weighted images) have negative values. Thanks @samuelstjean for letting me know!

The translation part of the affine matrix seems wrong, or at least does not place the center of the volume to position (0, 0, 0). (Thanks @jchoude for letting me...