Hi, Yes, you can get this information from FLIRT. Just do: flirt -in resampled_image -ref refimage -schedule measurecost1.sch You can also select the similarity metric you want with -cost ... The measurecost1.sch file has been posted on the list before, but I'm attaching another copy here. Just save it (as plain text) somewhere and give the full path in the command above. The cost value is the first number printed. If you want to automatically select only this then you can do: flirt .... | head -1 | cut -f1 -d' ' with the above flirt command. All the best, Mark