Hi Elsie,
for the maximum diameter, it is easy:
It is called "Feret's diameter" or "Caliper length", see the
documentation
http://rsb.info.nih.gov/ij/docs/menus/analyze.html#setThe minimum length - there are different approaches:
- Process>Binary>Ultimate Points gives you gray values that are equal
to the radius of the largest inscribed circle (not perfectly
accurate, some approximation). Measure the maximum value with
"redirect to" the "ultimate points" image to
http://rsb.info.nih.gov/ij/docs/menus/process.html#binary- Gabriel Landini's plugin calculates the radius of the inscribed
circle centred at the centre of mass
http://www.dentistry.bham.ac.uk/landinig/software/software.html- In the ImageJ Particle Analyzer, you could fit an ellipse. This
option has the advantage that it is not sensitive to noise or ragged
borders of the particles, but the major/minor axis of the ellipse
won't be equal to length/width of the particles unless they are
elliptic.
Michael
________________________________________________________________
On 8 Jan 2009, at 01:17, Elsie Tanadjaja wrote:
> Hi all,
>
> I'm new to this listserv and am not very experience with ImageJ. I
> need to
> measure tons of sediment particles (from my sediment cores) using
> imageJ to
> get the maximum and minimum length (height and width) of each
> particle.
> However, I haven't been able to find the right way to do this with
> imageJ.
> My particles are in random orientation and using the "analyze
> particle..."
> option, I realize that it uses bounding box for each particle which
> won't
> give me the maximum and minimum length of the particle axis but
> just the
> height and width of the bounding box itself.
>
> Any suggestion? Greatly appreciate your help.
>
> Elsie
>
>
> --
> Elsie Tanadjaja
> Graduate Student / Teaching Assistant
> Geological Oceanography / Teacher Enhancement Program
> Moss Landing Marine Labs.
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