radius of elliptical mask

how to design an elliptical mask for an input image? what should be its radius??

Answer 1

[Image Analyst]

See the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_create_an_ellipse.3F

Obviously the radius is up to you. It depends on the size of the thing in your image that you want to mask. There is no one size, or even rule of thumb, that works for every image in the universe, in case that's what you were thinking.

[Debanjana Debnath]

why need to use meshgrid??

[Image Analyst]

You don't have to. You only have to do that if you want the ellipse "solid". If you just want perimeter coordinates, you can use the second example.