Re: negative centroid values

Posted by Gwen Barnes on Jul 19, 2006; 11:35pm
URL: http://imagej.273.s1.nabble.com/negative-centroid-values-tp3702087p3702089.html

Great, thanks!

-Gwen

On 7/19/06, Wayne Rasband <[hidden email]> wrote:

>
> Search the release notes for "centroid" and you will find this:
>
>    v1.37g, 15 May 2006
>        Fixed a bug that could cause calculated centroid
>        coordinates to be incorrect with large images.
>
> -wayne
>
> On Jul 19, 2006, at 3:02 PM, Gwen Barnes wrote:
>
> > Hi folks,
> >
> > I'm trying to find the centroid of a circular object, but I sometimes
> > get
> > negative (!) values for X or Y.
> >
> > I outline it with the polygon tool, under "set measurements" I chose
> > area,
> > centroid, and feret's diameter, and then I select "analyze, measure."
> > Most
> > of the time this works fine.  However, if I encompass too large an
> > area, I
> > get negative values for either X or Y of the centroid.  My image is a
> > 41 M
> > tiff, 2552 pixels wide by 4200 pixels high.  My latest results from
> > "measure" were:
> >
> > area: 1210035
> > X:    1357.474
> > Y:    -1649.551
> > diam:    1343.317
> >
> > Whereas the actual values should be about:
> >
> > X:  1344
> > Y:  1944
> > diam: 1308
> >
> > In this case, maybe the Y value is the only incorrect one, but since
> > there's
> > no way the answer could be negative, it makes me distrust all the
> > values.
> >
> > Is anyone else familiar with this problem, and does anyone have
> > suggestions
> > for getting the right answer?  Thanks.
> >
> > -Gwen
> >
> > --
> > 01000111011101110110010101101110
> > 010000100110000101110010011011100110010101110011
> >
>