Hi Alfonso,
I came across a previous forum post here, http://www.nitrc.org/forum/message.php?m... , which I followed to create individual masks based on clusters from the export mask tool. However, the mask files output by the code were not aligned to the original mask or the canonical image in SPM - they have a different origin and I can't seem to align the crosshair when clicking on the image.   I apologize if I'm not explaining the issue clearly, so I'm attaching an .img file just in case and the exact code used was

spm_imcalc PCCmask.ROIs.img PCCmask.ROIs_1.img i1==1  

I'm running MATLAB R2013A with spm12 on a macbook pro. Is there something in the code or my settings that I should have changed?  Thanks so much in advance for your help.
-Denise