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Re: trouble specifying a ROI in ROI Manager

Posted by Hugo A. M. Torres on Feb 13, 2009; 8:27pm
URL: http://imagej.273.s1.nabble.com/Macros-to-read-and-write-Complex-Fourier-Transform-tp3693680p3693686.html

I tried that, didn't work. Maybe I am still having rounding issues
because of the area being reported in micrometers.

I am not experienced in writing macros, but would it be possible at
least in principle to write a macro that specifies a square ROI
according to an area value input?

Hugo

On Fri, 2009-02-13 at 13:41 +0100, joris meys wrote:

> Ah, I see. Sorry for the misunderstanding.
>
> As far as I understand, the ROI measures inside its boundaries, boundary not
> included. So in fact you should extend the length and width of the ROI with
> 2 pixels if you want to have a square that covers the same area. I'm not
> 100% sure about this, but it might be worth a try.
>
> Kind regards
> Joris
>
> On Fri, Feb 13, 2009 at 1:13 PM, Hugo A. M. Torres <[hidden email]>wrote:
>
> > No Joris, I understand what you are saying, but the problem is the first
> > ROI (used to measure the nucleus I am interested in) has a triangular
> > shape, which will not fit in the background area unless I make it into a
> > square of the same area as the triangle. Now, this should be very
> > straightforward: just draw a square with sides whose lenght is the
> > square root of the triangle area. It doesn't work if I use a calculator,
> > possibly because of rounding issues, I don't know.
> >
> > I always get a smaller area in um^2 if I do this by hand. So I was
> > wandering if it is possible to specify a square ROI by area value.
> >
> > Any ideas?
> >
> > Tganks
> >
> > On Fri, 2009-02-13 at 11:08 +0100, joris meys wrote:
> > > The measurements should be fairly simple with the ROI manager. Just click
> > on
> > > the roi you specified earlier, and drag it to where you want to measure.
> > > First click "Add", because otherwise the ROI manager will measure at the
> > > previous position. That should give you the results you want.
> > >
> > > Kind regards
> > > Joris
> > >
> > >
> > > On Fri, Feb 13, 2009 at 4:36 AM, Hugo A. M. Torres <[hidden email]
> > >wrote:
> > >
> > > > Hello listmates,
> > > >
> > > > I am trying to perform densitometry measurements according to this
> > > > method:
> > > >
> > > > "The nucleus was encircled by free-hand drawing of a border around the
> > > > outermost mRNA-expressing cells in the nucleus. The mean density and
> > the
> > > > area of the selection were measured. The mean density of the background
> > > > was measured from a rectangular area of corresponding size in the
> > > > immediate vicinity of the nucleus. The mean density of the background
> > > > was subtracted from the mean density of the nucleus and..."
> > > >
> > > > Now, the problem is I can't specify a ROI of the same area of the place
> > > > I measured previously. I tried taking the square root of the area
> > (given
> > > > in um^2) and specifying a square ROI with sides of this length but the
> > > > resulting area measured is always smaller!
> > > >
> > > > Is it possible to specify a square ROI by inputing  an area value in
> > > > square micrometers?
> > > >
> > > > Thanks
> > > > --
> > > > Hugo Arruda de Moura Torres
> > > > ==================================
> > > > Departamento de Biofísica
> > > > Universidade Federal de São Paulo
> > > > Rua Botucatu 862 7o. andar
> > > >
> > --
>
>