Apologies if this has been covered before.
Edit:- Mm-hm; I see it very definitely has...
Well, just to refresh the community's memory, I came across it, quite by accident, via a link from the Windows XP Forums, where I spend time, occasionally, trying to persuade the daft buggers to try out summat a wee bit more up-to-date & secure; Puppy, of course..!
We're now up to version 0.94. It's an awesome app, capable of a multitude of editing functions, in addition to being an extremely capable and versatile viewer, too. Its only 'drawback' (to my mind) is that the interface is a bit crowded.....exacerbated, in my case, by a relatively small 1024x768 screen.
But don't let that put you off. This one is well-worth adding to the 'arsenal'....
EDIT:- Plus (so I've only just discovered
), it'll playback videos, too!! Very neat, yes indeedy..... 
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Originally a Windoze app, it's been ported to both MacOS and Linux, too.
https://www.xnview.com/en/xnviewmp/
It's available either as 32- or 64-bit self-contained tarballs - everything required for it to run is included, even a whole load of Qt5 libs. Or, as a 64-bit only AppImage.
Download either of the tarballs; extract, put the resulting 'XnView' directory anywhere you like, and fire it up with the included xnview.sh script. It just 'works'. Set it up initially via the 'Startup Wizard' with a few simple options, and you're up-and-running.
TIP:- If you set the profile/settings & stuff to run from inside the directory itself, it saves the need to keep a copy of the .config file and sym-link it into each Pup you want to run it from.
Only tested in UPup 'Raring' and Bionicpup64 8.0 so far - the minimum required glibc, it seems, is 2.17 - but I'm betting it'll run in most of my Pups, since the older ones (anything older than Tahrpup, really) all have battleshooter's 'Glibc-2.20' upgrade.
The AppImage fires straight up in Bionic64, after making it executable. I don't foresee any problems with it running in Xenialpup64, either. (EDIT:- Yep, as expected; fires straight up in Xenial64, too.)
Downloads from here:-
https://www.xnview.com/en/xnviewmp/#downloads
Have fun.
Mike.
