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Roi-Contour is smaller as expected

Posted by jumpfunky on Dec 14, 2012; 11:08am
URL: http://imagej.273.s1.nabble.com/Roi-Contour-is-smaller-as-expected-tp5001160.html

Hi
i've used a contour tracing algorithm to extracted the contour of the following object:
https://dl.dropbox.com/u/560426/imagej/object.png

The extracted polygon is described by the following points:
int[] xpoints = {3,4,5,6,7,8,9,10,11,11,11,10,9,8,7,6,5,4,3,2,2,2,3};
int[] ypoints = {1,1,2,2,2,1,1,2,2,3,4,4,5,5,4,4,4,5,5,4,3,2,1};
These Points seems to be correct.

I've now converted this polygon to a PolygonRoi and add it to the RoiManager:
Roi roi = new PolygonRoi(mypolygon, Roi.POLYGON);
roiManager.add(imp, roi, n);

If I click on the added Roi in the ROI-Manager the overlayed contour is smaller than expected:
https://dl.dropbox.com/u/560426/imagej/contour_imagej.png

Where is my fault?

Best wishes
Thorsten

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