A tutorial describing my workflow for quickly analyzing the airway lumen area of a large number of lung slice images in ImageJ (FIJI).
The images used in the analysis are .TIFF files at ~20x magnification. While in this analysis I remove the scale, you can calibrate it according to your setup.
There are quite a few different types of filters, etc. in ImageJ that may help you get the most out of your images and speed up your process that I did not cover here.
FIJI: http://fiji.sc/
Twitter: / camkieff