Re: Minimum Feret Diameter

Posted by Gabriel Landini on Jan 17, 2009; 10:17am
URL: http://imagej.273.s1.nabble.com/Minimum-Feret-Diameter-tp3694020p3694024.html

On Friday 16 January 2009, alisona5 wrote:
> Is there a way to measure Minimum Feret Diameter in ImageJ.   I have seen
> posts on various sites discussing that it is in the source code, but is
> commented out.  However, I have not seen any resolution to this issue.  I
> need to measure the minimal feret diameter :the minimum distance of
> parallel tangents at opposing borders.  This is the accepted parameter in
> my field and I cannot use any other measurements.

Note however that the *original* definition of the Feret Diameter considers  
one direction of scan (i.e. not the rotating callipers, but the "height" or
the "width" of the object bounding rectangle in a fixed direction for all
particles). The minimum FD  which is estimated from the population, not for
every particle, is likely to be overestimated (as one cannot guarantee that
the thinnest particles would be orientated in such a way that the scan
direction corresponds exactly to the perpendicular to the smallest diameter).

The rotating callipers, will give you the smallest possible diameter of the
convex hull, but for the reasons above, that is likely to be smaller than
other estimates of FD using the traditional method.

Some old imaging analysers used to incorporate more than one direction of scan
to improve the stats, but the problem remains essentially the same.
Search Google for:
A Guide to Pharmaceutical Particulate Science by Crowder et al
You can read that in page 63.

From your description, it seems that you are looking for  the minimal rotating
calliper (or convex hull) diameter of each particle, but strictly speaking
that is not the minimal FD.
Perhaps one should be careful about comparisons of the rotating calliper
results with other people's data minimum FD.

Regards,

G.