How to chose structuring element?

Question

I am new to image processing and related areas. I am trying to figure out how to chose structuring element (strel) for Morphological operations? For eg: I want to dilate a binary image in Matlab but I am not sure which strel to chose. That's proving to be really difficult since which is used when isn't clear to me. I am basically procssing large number of video frames and the algorithm demands dilation of each after binarization.

Answer 1

I advise you using SE = strel('disk', R, N); R depends on your image size and your purpose and N is the neighbourhood, usually 4 or 8. But experimenting with different strel elements is not difficult, you can try all and decide the best for yourself

Answer 2

When you dilate, the shape of the structuring element is the shape a single isolated pixel will transform into.

Which shape you choose depends a lot on the type of features you're dilating. For example, if you dilate rectangular shapes that are aligned with the image axes, you'll want to use a square shape, so that you retain sharp corners. Conversely, if the shapes are arbitrary and smooth, you'll want to use a circular shape (disk), and so on. Here's an example where I used a rectangular structuring element.