Many users have created masks from a T-test image; xjView also allows you to create a mask based anatomy. Say, if you want to create a mask of Amygdala, how to do that?
(You need to use xjview 8.10. 1 min video demo at http://youtu.be/31q_6jumhhM)
1. launch xjview without any argument
2. don’t open any images
3. select an anatomical region (say Amygdala) in the box right to “Overlay” button
4. xjview will relaunch, and amygdala is shown
5. click menu “File -> Save current image as mask” to save a mask file