MATLAB Central Newsreader - geometry center

geometry center

ahmed — Wed, 23 Apr 2008 08:23:03 -0400

I wan't to move adrawing to the center of the image.
i know that i have to find the geometric center of the
image
and move the drawing pixels such that the geometric center
should reside at center of image.
but i don't know how to implement these stepe in matlab
can you help me.

Re: geometry center

alessandro mura — Wed, 23 Apr 2008 09:48:00 -0400

I don't know exactly what is the center of a color image,
but for a gray scale:

[x,y]=ndgrid([1:100],[1:100]);
z=exp(-((x-50)/10).^2-((y-24)/10).^2);
subplot(1,2,1)
pcolor(x,y,z)
colormap gray

xc=mean(x(:).*z(:))/mean(z(:))
yc=mean(y(:).*z(:))/mean(z(:))
subplot(1,2,2)
pcolor(x-xc,y-yc,z)

regards

Alessandro

--
Alessandro Mura
Istituto Nazionale di Astrofisica - IFSI
http://pptt4.ifsi-roma.inaf.it/~mura/index.html

Re: geometry center

chandni magoo — Mon, 05 Jan 2009 16:47:01 -0500

hi
i wanted to know the method of finding geometric center of an image

"Ahmed " <mogwari2000@yahoo.com> wrote in message <fumrl7$4ck$1@fred.mathworks.com>...
> I wan't to move adrawing to the center of the image.
> i know that i have to find the geometric center of the
> image
> and move the drawing pixels such that the geometric center
> should reside at center of image.
> but i don't know how to implement these stepe in matlab
> can you help me.
>

Re: geometry center

Adam — Mon, 05 Jan 2009 17:06:02 -0500

"chandni magoo" <chandnimalh@gmail.com> wrote in message <gjtdi5$avk$1@fred.mathworks.com>...
> hi
> i wanted to know the method of finding geometric center of an image

[nRow nCol] = size(theImage);
xCenter = nCol/2;
yCenter = nRow/2;

~Adam

Re: geometry center

Matt — Mon, 05 Jan 2009 17:35:03 -0500

"Adam" <not.real@email.com> wrote in message <gjtelq$nga$1@fred.mathworks.com>...
> "chandni magoo" <chandnimalh@gmail.com> wrote in message <gjtdi5$avk$1@fred.mathworks.com>...
> > hi
> > i wanted to know the method of finding geometric center of an image
>
>
> [nRow nCol] = size(theImage);
> xCenter = nCol/2;
> yCenter = nRow/2;
>
> ~Adam

Actually, because MATLAB uses 1-based indexing, you will probably want

[nRow nCol] = size(theImage);
xCenter = (nCol+1)/2;
yCenter = (nRow+1)/2;