I am trying to measure area with image J, something I have done before. I open an image, use the straight line tool to draw a line, and click on Set Scale. I then add the known distance (1cm) and and click OK (using pixel aspect ratio of 1) . When I measure straight lines I get the right lenght (1cm=1), but any area measurements are all wrong. A 1cm2 square will yeild 0.05 for area.
How could that be? Any advice?
Thanks so much!