Calculate the diameter of the circle in the picture

[vdoo]

  Hello,

I am trying to identify the diameter of a circle in an image. The backgroundmay change but the circle object will remain black or any other solid color. I needto calculate the diameter of the circle in the picture attached. Is there an IMAGEJplugin.  Else any pointer to steps/algorithm would be much appreciated!!Thanks,Vdoous

--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html

[dscho]

Hi Vdoous,

On Wed, 29 Oct 2014, vdoo wrote:

> I am trying to identify the diameter of a circle in an image. The
> backgroundmay change but the circle object will remain black or any
> other solid color. I needto calculate the diameter of the circle in the
> picture attached. Is there an IMAGEJplugin.  Else any pointer to
> steps/algorithm would be much appreciated!!

There is a Circle Fitter plugin in Fiji's Fiji_Plugins set of plugins.
Unfortunately, there is no documentation for it yet (writing a page about
it on the Wiki would be an excellent way to become part of the ImageJ/Fiji
community).

This plugin expects an image with background values as close to zero as
you can make it, and roughly identical, positive foreground values,
though. You can make that happen with your image by (auto-)thresholding
and then inverting it.

Ciao,
Johannes

--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html