Try the viewer on the "cave" image
The IAS 3.1 viewer has an option where you can do contrast enhancement.
Anyone want to try getting some more information out of that black spot in this image:
HiRISE | Candidate Cavern Entrance Northeast of Arsia Mons (PSP_003647_1745).
http://hirise.lpl.arizona.edu/PSP_003647_1745
Bob Clark
