Posted by
Ben Tupper on
Aug 09, 2008; 2:15pm
URL: http://imagej.273.s1.nabble.com/center-of-mass-tp3695425p3695426.html
On Aug 9, 2008, at 8:45 AM, Partha Goswami wrote:
> Hi,
> I want to get one information regarding center of mass to get the
> center of
> particles in a image.
> to get it I need to do *Image>Adjust>Threshold.
> *which makes my gray image to binary.*
> *Therefore If I analize the particle to get center of mass It does
> not give
> weighted average grayscale center of mass,
> rather gives centroid ( just average of the pixel position). Is
> there any
> procedure so that I can get center of mass of the particles, which
> is the brightness-weighted average of the x and y coordinates all
> pixels in
> the image.
>
Hi,
The Analyzer does give you the option to retrieve the CM and/or the
centroid. But you need to "redirect" the measurements to the
original greyscale image using the blobs extracted from your binary
image. Check the documentation at
http://rsb.info.nih.gov/ij/docs/
menus/analyze.html#ap (and see the snippet below).
> Centroid - The center point of the selection. This is the average
> of the x and y coordinates of all of the pixels in the image or
> selection. Uses the X and Y Results table headings.
>
> Center of Mass - This is the brightness-weighted average of the x
> and y coordinates all pixels in the image or selection. Uses the XM
> and YM headings. These coordinates are the first order spatial
> moments.
and ...
> Redirect To - The image selected from this popup menu will be used
> as the target for statistical calculations done by the Measure and
> Analyze Particles commands. The Redirect To feature allows you to
> outline a structure on one image and measure the intensity of the
> corresponding region in another image. With ImageJ 1.35d or later
> this feature also works with stacks.
Cheers,
Ben
Ben Tupper
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