Linux goesZen

Why would you want an alternative for eog on Ubuntu/Debian Linux?, Well...

eog
https://projects.gnome.org/eog/

• is still not lightweight enoug (means: fast startup)
• no proper previewing of large JPGs (loads whole file instead of preview first, then full res)
• the annoyance of opening images at 95% even when there's enough screen property around it left
• after zooming, arrow keys become "image panning navigation" instead of prev/next image, but an ENTER exists that and brings you to "next". (btw: ALT+Arrows forces previous/next)
• I would like a simple info-overlay in full-screen mode: zoom ratio, file name, size

So, let's have a look around:

feh
http://feh.finalrewind.org/

• very quick startup but no zooming via mouse-wheel, no full-screen-click
• "bare metal", as it's a CLI viewer...
• no JPG preview reading

Mirage
http://mirageiv.berlios.de/

• surprisingly slow startup for a lightweight image viewer, slow on image loading
• no JPG preview reading

Ristretto
http://goodies.xfce.org/projects/applications/ristretto

• comes fromthe xfce project, thus with all the xfce basic dependencies,
• no JPG preview reading
• start up on par with eog
• no mouse-wheel zoom

GPicView
lxde.sourceforge.net/gpicview/‎

• Fast startup, fast image loading
• no JPG preview reading
• mouse-wheel zoom only if you hold down CTRL! Default is to cycle through images (changed around between versions 0.1.10 and previous 0.1.7)

ViewNior   (*** WINNER)
http://xsisqox.github.io/Viewnior/about.html

• no debian package yet, as of this writing
• very fast startup, twice as fast as eog
• even zoom anti-aliasing is configurable
• on startup, images are properly zoomed at 100% if screen property allows it (and that's even configurable!)
• behaves like eog (but!): after zooming, arrow keys become "image panning navigation" instead of prev/next image, but an ENTER *does not* bring you to "next". (still: ALT+Arrows forces previous/next)
• no JPG preview reading

I also came across these, but didn't test them:

gThumb

• seems feature ladden
• untested

kuickshow
http://kuickshow.sourceforge.net/

• dead
• from KDE project, thus with all the dependencies
• comes with preview sidebar (probably slow on startup)
• untested

Gwenview

• from KDE project, thus with all the dependencies
• comes with bells&whsitles (probably slow on startup)
• untested