MATLAB: Find all rectangle(or another shape like circle, square, and triangle) in image

Question

Hi.

I want to fine corners of rectangle in images for tracking changing coordination. For this, i think that find edge and corners of rectangle first.

How to find all rectangle's outline.

I attached 2 images. The attached image have 40 rectangles. I want to get "40". However, the image have noise. How to i get target's exactly number.

Please, help me.

Thanks.

.

Noise Rectangle 1

Noise Rectangle 2

Answer 1

Find the red stuff using color segmentation. Then erode the mask to separate the squares. Then examine each blob to see how many vertices it has and determine if it's a square, triangle, pentagon, or whatever. See attached demo.