How to center an ellipse?

[Juanjo Vega]

Hello!

I'm trying to center an ellipse ROI in an ImagePlus.

I have the following method, which gets a ROI, fits an ellipse, sets it's center (x and y), and then tries to refresh it, so the ellipse will be moved to the center of the image:

    public void fitEllipse() {
        Roi roi = ip.getRoi();

        if (roi != null && roi.isArea()) {
            IJ.run(ip, "Fit Ellipse", "");
            ImageStatistics is = ip.getStatistics();
            EllipseFitter ef = new EllipseFitter();
            ef.fit(ip.getProcessor(), is);

            // Builds an ellipse...
            ef.xCenter = ip.getHeight() / 2;
            ef.yCenter = ip.getHeight() / 2;

//            IJ.run("Select None");
            ef.makeRoi(ip.getProcessor());
        }
    }

The last part doesn't work and I'm sort of ideas. Does anybody can help me, please?

Have a nice weekend,

Juanjo.

------------------------------------------------------------
Juanjo Vega ([hidden email])

Unidad de Biocomputación. Laboratorio B-13.
Centro Nacional de Biotecnología. CNB-CSIC.
C\ Darwin, 3. Campus de Cantoblanco.
Universidad Autónoma de Madrid.
28049, Madrid, Spain.

http://www.cnb.csic.es
http://www.biocomp.cnb.csic.es

[phone]

"Las mejores almas son capaces de los mayores vicios como de las mayores
virtudes, y aquellos que caminan despacio por el camino recto pueden
llegar más lejos que los que corren pero se apartan de él." - Discurso
del Método, René Descartes.

[Rasband, Wayne (NIH/NIMH) [E]]

On Apr 8, 2011, at 9:33 AM, Juanjo Vega wrote:

> Hello!
>
> I'm trying to center an ellipse ROI in an ImagePlus.
>
> I have the following method, which gets a ROI, fits an ellipse, sets it's center (x and y), and then tries to refresh it, so the ellipse will be moved to the center of the image:
>
>    public void fitEllipse() {
>        Roi roi = ip.getRoi();
>
>        if (roi != null && roi.isArea()) {
>            IJ.run(ip, "Fit Ellipse", "");
>            ImageStatistics is = ip.getStatistics();
>            EllipseFitter ef = new EllipseFitter();
>            ef.fit(ip.getProcessor(), is);
>
>            // Builds an ellipse...
>            ef.xCenter = ip.getHeight() / 2;
>            ef.yCenter = ip.getHeight() / 2;
>
> //            IJ.run("Select None");
>            ef.makeRoi(ip.getProcessor());
>        }
>    }
>
> The last part doesn't work and I'm sort of ideas. Does anybody can help me, please?

... [show rest of quote]

Here is JavaScript code that gets the current ROI, fits an ellipse to it and then moves the resulting elliptical ROI to the center of the image.

-wayne

   imp = IJ.getImage();
   roi = imp.getRoi();
   if (roi!=null && roi.isArea()) {
      IJ.run(imp, "Fit Ellipse", "");
      roi = imp.getRoi();
      r = roi.getBounds();
      xcenter = r.x+r.width/2;
      ycenter = r.y+r.height/2;
      dx = imp.getWidth()/2-xcenter;
      dy = imp.getHeight()/2-ycenter;
      roi.setLocation(r.x+dx, r.y+dy);
      imp.draw();
    }

[Juanjo Vega]

It works!! Thanks!! :)

On Apr 8, 2011, at 5:48 PM, Rasband, Wayne (NIH/NIMH) [E] wrote:

> On Apr 8, 2011, at 9:33 AM, Juanjo Vega wrote:
>
>> Hello!
>>
>> I'm trying to center an ellipse ROI in an ImagePlus.
>>
>> I have the following method, which gets a ROI, fits an ellipse, sets it's center (x and y), and then tries to refresh it, so the ellipse will be moved to the center of the image:
>>
>>   public void fitEllipse() {
>>       Roi roi = ip.getRoi();
>>
>>       if (roi != null && roi.isArea()) {
>>           IJ.run(ip, "Fit Ellipse", "");
>>           ImageStatistics is = ip.getStatistics();
>>           EllipseFitter ef = new EllipseFitter();
>>           ef.fit(ip.getProcessor(), is);
>>
>>           // Builds an ellipse...
>>           ef.xCenter = ip.getHeight() / 2;
>>           ef.yCenter = ip.getHeight() / 2;
>>
>> //            IJ.run("Select None");
>>           ef.makeRoi(ip.getProcessor());
>>       }
>>   }
>>
>> The last part doesn't work and I'm sort of ideas. Does anybody can help me, please?
>
> Here is JavaScript code that gets the current ROI, fits an ellipse to it and then moves the resulting elliptical ROI to the center of the image.
>
> -wayne
>
>   imp = IJ.getImage();
>   roi = imp.getRoi();
>   if (roi!=null && roi.isArea()) {
>      IJ.run(imp, "Fit Ellipse", "");
>      roi = imp.getRoi();
>      r = roi.getBounds();
>      xcenter = r.x+r.width/2;
>      ycenter = r.y+r.height/2;
>      dx = imp.getWidth()/2-xcenter;
>      dy = imp.getHeight()/2-ycenter;
>      roi.setLocation(r.x+dx, r.y+dy);
>      imp.draw();
>    }

... [show rest of quote]

------------------------------------------------------------
Juanjo Vega ([hidden email])

Unidad de Biocomputación. Laboratorio B-13.
Centro Nacional de Biotecnología. CNB-CSIC.
C\ Darwin, 3. Campus de Cantoblanco.
Universidad Autónoma de Madrid.
28049, Madrid, Spain.

http://www.cnb.csic.es
http://www.biocomp.cnb.csic.es

[phone]

"Las mejores almas son capaces de los mayores vicios como de las mayores
virtudes, y aquellos que caminan despacio por el camino recto pueden
llegar más lejos que los que corren pero se apartan de él." - Discurso
del Método, René Descartes.