Major axis and minor axis

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Pamela
Pamela on 26 Aug 2012
How can I plot the major axis and minor axis for an object in an image?
  2 Comments
Pamela
Pamela on 1 Sep 2012
I need your held please !!
Image Analyst
Image Analyst on 10 Nov 2012
I've just added a section on "How do I create an ellipse" to the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_create_an_ellipse.3F so that might help you.

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Accepted Answer

Walter Roberson
Walter Roberson on 27 Aug 2012
regionprops() to get the centroid and orientation (angle). After that it becomes straight trig. The axes length is R, compute R*cos(theta), R*sin(theta), and center those displacements on the centroid.
  17 Comments
Pamela
Pamela on 9 Sep 2012
Edited: Pamela on 9 Sep 2012
Hi! To study the similarity between 2 images we should use these steps???
-Calculate the mean of the input images
-Subtract the mean from the input images to obtain the mean-shifted images
-Calculate the eigenvectors and eigenvalues of the mean-shifted images
-Order the eigenvectors by their corresponding eigenvalues, in decreasing order
-Retain only the eigenvectors with the largest eigenvalues (the principal components)
-Project the mean-shifted images into the eigenspace using the retained eigenvectors
-Calculate the Euclidean distance
It's the same solution to study the asymmetry of the region?? Can this help me??
Thanks
Image Analyst
Image Analyst on 9 Sep 2012
Pamela, I haven't heard of that method to determine similarity. Much more common is SSIM ( http://en.wikipedia.org/wiki/SSIM) and friends, or even PSNR. Or you can use image moments: http://en.wikipedia.org/wiki/Image_moment

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