Following some more testing, in particular with files at https://github.com/bitsgalore/jp2kMagic/tree/master/sampleImages, I've added some of the proposed extensions to xv upstream and left out jpm and mj2 which it doesn't display for me. qiv doesn't seem to support any of these files, and I still don't have access to ee to test with.
https://github.com/scop/bash-completion/commit/0de9b7b086574213d21b28c25d1bd5d517880ba0
