Also, the order of first two inputs is wrong in the IJ paper, should be

cmtk unwarp_image_phantom --final-cp-spacing 40 --levels 2 phantom.xml  phantom.nii  unwarp.xform

instead of 

cmtk unwarp_image_phantom --final-cp-spacing 40 --levels 2 phantom.nii  phantom.xml  unwarp.xform


btw, a separate question, what would cause

snr: inf
cnr: nan nan nan inf

at the beginning of the phantom.xml file

ThanksGordon