Irfanview: possible image viewer app for USB in existance
I have been using Irfanview (see www.irfanview.com)
for many years. I have used it on my USB stick without
a problem. None of the needed files have to be on the
hard drive. It is a small app with powerful viewer
abilities and with its ability to modify and convert
images, it is "ready to go!"
I suggest that PortableApps.com seek it out!