Hi Yili,
you can simply use the equation given there in ImageJ:
4*pi*area/perimeter^2
Make sure you have "Area" and "Perimeter" checked in the Measurement
options and use "Analyze Particles". Then, use either a spreadsheet
or a simple macro to determine this quantity for your objects.
for (i=0; i<nResults; i++) {
perimeter = getResult("Perim.",i);
area = getResult("Area",i);
setResult("metric", i, 4*PI*area/(perimeter*perimeter));
}
Due to the ragged outlines caused by single pixels, a circle won't
give you a 'metric' value of 1, but only slightly above 0.9,. A
square will give you pi/4 in the ideal case, but values like 0.82
might also occur (again, because of finite pixel size).
Michael
________________________________________________________________
On 25 May 2011, at 16:27, Yili Zhao wrote:
> Hi,
> Matlab has a demo named : "Identifying Round Objects" in the
> Image Processing Toolbox, which using bwboundaries, a boundary tracing
> routine.
> I want to do the same task in ImageJ,
> and I want to know if there are some guides showing how to
> complete this task, or there is a plugin which can do boundary
> tracing?
> Otherwise, maybe I should write it myself?
> Thanks!
>
> reference
>
http://www.mathworks.com/products/image/demos.html?file=/products/
> demos/shipping/images/ipexroundness.html
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