Hi everyone,
I'm posting some responses from the R-sig-ecology mailing list:
1. http://www.wsl.ch/dienstleistungen/hemisfer/features_EN
This is a software that runs under Windows. I was able to install it
under Vista. It's free to use with some pixel limitations.
2. Another person said " I have not used R for analyzing hemispherical
photos, but I have been
playing around with Python and the Python Image Library (PIL) that can do a
lot of very simple imaging tasks. I bet that you could write a very simple
program to threshold and count pixels in Python. Why I bring up Python is
that it also integrates really well with R, using the Python package rpy,
such that you can write Python code and call R functions (this is what I
like to do, as I can understand Python programs a bit better than R ones)."
Ophelia