Image editor. Sometimes compared to IrfanView on the Windows platform. The alternative XnViewMP means Multi Platform, though the differences are unclear.

Download and install an appropriate software package:-

XnView
XnView 1.70 version4.00 pet
XnView 1.70 patched-i486-slxr pet

XnViewMP
XnViewMP 0.51 sfs by bwh1969
xnviewMP xncorverter 0.39-1.1 pet/sfs by pemasu

Alternatively, compile a source:-
XnViewMP source

XnView homepage
XnView Feature Pages
XnView forum
Best program for managing photos in Puppy? thread