Hi Erik -

Probably about time for an update.

I looked into making groupwise_init work without creating an average image (the part that seems to be crashing for you), but it turns out that that isn't actually that simple to do. Long story short, the transformation files that are being created have to refer to some common space across all input images, and that common space is provided by the average. No average, no common space, no transformations.

That said, the latest code in the svn repository adds a bunch of command line options that allow you to pick a different pixel data type (previously, the type was float). So you could use, say, "byte", to greatly reduce memory consumption. In addition, I have changed an internal array from short to byte, which also reduces the amount of memory needed. Just in case this was indeed originally a memory issue, you may want to give the latest code a try (assuming you build your own binaries; otherwise let me know and I'll make some for you).

Sorry I don't have a complete solution, but maybe this is going to help you move forward.

Torsten