Circularity error?

Posted by Adam Hughes on Feb 19, 2014; 6:47pm
URL: http://imagej.273.s1.nabble.com/Circularity-error-tp5006583.html

Hi,

I made an image of increasing circles to see how the circularity changed as
a function of circle radius, where I used another library to draw the
circles.

I discovered that if I compute the circularity using the formula  4 pi  * (
area / perim**2), the result is diferent than if I plot the output of
circularity.  All of the values of area, perimeter and circularity were
taken directly from imageJ analyze particles.

It looks like the circularty has some sort of correction in place?

I've attached the scatter pot showing these results and the test data used
for the particles.

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