[ECOLOG-L] Photo analysis question

[Beth Strain]

Dear Ecology List Server
I have recently been given a set of photos which I would like to
 convert into densities of species. The photos were taken haphardly but
do not contain a quadrat or transect. The photos cover a 1-2 m area. I
wanted to ask if anyone had any suggestions about how to calculate the
area of the photo.
Thanks for your help
Beth Strain.