For Information, a workaround to have a kind of "Xnview shell extension" for Linux too (with nautilus scripts)
Some good samples here:
http://linuxfr.org/users/yekcim/journau ... us-scripts
To download the scripts.zip file:
https://github.com/yeKcim/my_nautilus_scripts
PS:... Some scripts (own/custom scripts) can be built with nconvert too for example.