Dear SPMers, Dear John, does anybody have experience or perhaps a script how to calculate the signal to noise ratio (SNR) and the contrast to noise ratio (CNR) of structure images. I will appreciate any help Mutaz Qunaibi M.Sc. Dipl.-Ing. Mutaz Qunaibi Klinik für Psychiatrie und Psychotherapie Universitätsklinikum Aachen Pauwelsstr. 30 D-52074 Aachen Tel.: +49 241 8089497 FAX: +49 241 803389497 email: [log in to unmask]