I managed to get it working from any diretory, it's a bit fussy about
things.  Anyway here's what I put in my .octaverc, where
<my octave directory> is the directory containing image.m.


## System-wide startup file for Octave.
##
## This file should contain any commands that should be executed each
## time Octave starts for every user at this site.

PAGER = "/usr/bin/less"
LOADPATH = "<my octave directory>:/usr/local/share/octave/2.1.36/:"