fit ellipse with noise

Hello,

I have an image with something looking like an ellipse and some noise within the ellipse (see below).

I would like to determine the coordinates of the ellipse centre through ellipse fitting. In addition, I would like to have the uncertainty on these coordinates (like diag(sqrt(CovB)) with nlinfit).

Is there a MATLAB function that can help me remove the noise?

Should I use nlinfit with ellipse function as model or is there another function that is more appropriate?

Thanks! Guillaume

Answer 1

[Image Analyst]

The most accurate answer is given in the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_fit_an_ellipse_or_other_shape_to_a_set_of_XY_data.3F

That said, an easier answer is to fill the ellipse with imfill() then use regionprops() to get the centroid, orientation, and MajorAxisLength, and MinorAxisLength. If you need a tutorial in regionprops(), see my Image Segmentation Tutorial in my File Exchange http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862. Let me know if you need help