trouble specifying a ROI in ROI Manager

Posted by Hugo A. M. Torres on Feb 13, 2009; 3:36am
URL: http://imagej.273.s1.nabble.com/Macros-to-read-and-write-Complex-Fourier-Transform-tp3693680p3693682.html

Hello listmates,

I am trying to perform densitometry measurements according to this
method:

"The nucleus was encircled by free-hand drawing of a border around the
outermost mRNA-expressing cells in the nucleus. The mean density and the
area of the selection were measured. The mean density of the background
was measured from a rectangular area of corresponding size in the
immediate vicinity of the nucleus. The mean density of the background
was subtracted from the mean density of the nucleus and..."

Now, the problem is I can't specify a ROI of the same area of the place
I measured previously. I tried taking the square root of the area (given
in um^2) and specifying a square ROI with sides of this length but the
resulting area measured is always smaller!

Is it possible to specify a square ROI by inputing  an area value in
square micrometers?

Thanks
--
Hugo Arruda de Moura Torres
==================================
Departamento de Biofísica
Universidade Federal de São Paulo
Rua Botucatu 862 7o. andar