Yesterday, I received an email asking me about a versatile jpeg image viewer for UNIX. My initial thoughts were to use the common browser or the image related utilities in /usr/openwin/bin -- imagetool or snapshot.
Then I started thinking about XV. XV is a popular image viewing shareware program. I have found it to be very effective at resizing screenshots, cropping, expanding, and converting images to different image formats. Personally, I've been using XV (3.10 and now 3.10a) for a number of years without complaint.
Here's another reliable source for XV Image Viewer.
I installed xv in my /opt/apps directory.
# /opt/apps/xv &