How to extract different shapes from an Image

Question

I am a newbie in Image processing world and I have a problem statement which I need a head start to solve it.

Problem Statement:

I have an i

Answer 1

You can use the dots to locate the individual shapes (binarization + connected components labeling).

Then it is an easy matter to detect the absence/presence of square corners, for instance by means of small windows between pairs of neighboring shapes. This will give you a binary code that you can use to distinguish your patterns.