Posted by
Christian Goosmann-2 on
Aug 12, 2013; 8:42am
URL: http://imagej.273.s1.nabble.com/SIZE-MEASUREMENT-OF-PARTICLES-THESIS-DUE-TOMORROW-PLEASE-HELP-tp5004387p5004390.html
Hi Geology Guy,
If I haven't misunderstood something, feret diameter is the smallest
diameter that you get when you rotate an object. Like the smallest gap
you could fit it through. First of all it is somehow connected to area
but it is in a different dimension because it is a length [µm] and not
an area [µm²]. For a perfect circle '(feret/2)² * pi' is the area, for a
square it is '(feret/2)²*4' so you see, the shape matters in how feret
relates to area. I would think that area is more precise when comparing
"sizes" but that depends on your experiment. If "sizes" means the
opening of gaps for other particles to pass through for instance, feret
diameters could make more sense measuring than areas which could belong
to irregular shapes. So if you ask how big is an object, if you want to
know volume, weight, or such, use area. If you ask how big must the gap
be where you can fit this object through, feret is not such a bad idea,
though beware, if you only have a cross section of a more irregular
object in three dimensional space to judge.
Hth
Christian
---
Christian Goosmann
Mikroskopie
Max-Planck-Institut für Infektionsbiologie
Campus Charité Mitte
Charitéplatz 1
10117 Berlin
Tel.: +49 30 28460 388
Geology Guy wrote:
> <
http://imagej.1557.x6.nabble.com/file/n5004387/Image_J_Picture.png>
> Good Evening Everyone,
> I need to measure the size of particles within the yellow boundaries in the
> image I attached. I learnt that size of objects or particles can be measured
> using either "Fit Ellipse" "Feret Diameter" or "Area". The purpose of my
> thesis is that I want to see if there is a relationship between the size of
> the particles within that yellow boundary and overall size of the space
> between them. I used "Area" in all the graphs I plotted but now my Professor
> is asking me why I did not use the Feret diameter instead. I used "Area"
> instead of "Feret Diameter" because someone on here told me that "Area" in
> Image J is a better estimate than "Feret Diameter" for the size of an
> object? Anyway I have no idea why the former is better than the latter and
> was wondering if someone can please clarify this.
>
> My thesis is 10 hours from writing this message.
>
> Thank you all for your help.
>
>
>
> --
> View this message in context:
http://imagej.1557.x6.nabble.com/SIZE-MEASUREMENT-OF-PARTICLES-THESIS-DUE-TOMORROW-PLEASE-HELP-tp5004387.html> Sent from the ImageJ mailing list archive at Nabble.com.
>
> --
> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html--
ImageJ mailing list:
http://imagej.nih.gov/ij/list.html