how eccentricity work?

hi everyone

for regionprps command we have a property that call eccentricity. I searched and studied matlab help about this. but I don't understand how this code work? for example if we have these ellipse :

Is ImgLabel(1).Eccentricity and ImgLabel(2).Eccentricity equal for these objects? why? these objects are like each other but you can imagine that one of them rotated. I mean that is it important that our object be Horizontal or vertical ? thanks

Answer 1

[Image Analyst]

First of all, MATLAB calls white objects as foreground, not black objects. So you'd have to invert your images or call imclearborder() to remove the white surround.

After that it fits each blob to an ellipse, and whatever the eccentricity of the fitted ellipse is, that's what it gives you. It does not depend on the "orientation" (angle) of the ellipse.