🚀 go-pugleaf

	I've got several MRI images of the brain, taken over period of
time (minutes), and there's some slight movement of the head between
images.  I'd like to "register" these images, that is, align them so
the images all overlap exactly.  I do not have any external markers to
use as reference points (fiducials), BTW.

	What is a good way to go about this?   It appears that without fiducials,
automatic image registration has been attempted in various ways, from
superposition of centroids and principal axes (?) to correlation using FFTs to
contour matching via Hough transforms...anyone care to comment on what might be
the "best" solution for my purposes?

	Also, I'm wondering what kind of error (in the pixel values) I might
introduce by registration and how I might quantify it.  Is it possible to align
images with subpixel accuracy?   How does resampling the image affect my
interpretation of the pixel value? (Like "its an average signal value, plus x
percent error introduced by resampling after rotation" ??)

	I'm a newcomer to image processing.  Any pointers, solutions, etc.
very much appreciated.

Steve
tirone@neurocog.lrdc.pitt.edu