polygon over polygon overlay in imagej

[robert franklin canto]

Hi All,

I'm a new user of imagej. I have photos of coral reef substrate cover taken
over the same area (50 x 50 cm dimension) but at different months.

Currently, I'm trying to figure out If


    I can draw polygons representing a given cover type for each photo and
save the polygons to a  file( i know i can do this using roi but)


    Can i overlay the a polygon file with another polygon file?

        what i wanted to do here basically is to measure     1) change in
polygon size over time 2) changes in  polygon type (e.g. if it was Type A
before but changed to Type B) over time



Will be glad to hear If anyone knows of a plugin or a way of how this can be
done with imagej (or if this task is possible). Thank you very much.


Regards,

Robert canto


--
******************************************************
Robert Franklin C. Canto
PhD Research Student
Centre for Remote Sensing & Spatial Information Science
School of Geography, Planning and Environmental Management
University of Queensland St Lucia
Brisbane, Queensland 4072, Australia
Office Phone: [phone] / Office Fax: [phone]
Mobile: [phone]
*****************************************************

[gilles]

Hi,
I think you may use the "ROI manager" tool. In the Analyse/Tools menu : http://rsbweb.nih.gov/ij/docs/menus/analyze.html#manager

So with this ROI manager you can select all your area in each photo and name them. Then You select one or many regions and make all your measures