How can I extract similar objects in an image?

Hello every one.

Thank you in advance for your help.

I want to extract automatically shape q from image b. As you can see, there are four of shape q.

I do not know how?

I tried to use feature extraction but it did not work.

Please help me.

Answer 1

[Image Analyst]

First try using either normalized cross correlation, demo script attached below this message,

or Hu's image moments: https://www.youtube.com/watch?v=Nc06tlZAv_Q

[Ro Shu]

Thank you for your answer. The problem is that i do not know the position of template and it depends on angle in which picture is taken, it can change. I am thinking about extract my object (insulator) by its area, but I am not sure it is a good idea or not

[Ro Shu]

Also what do you think about extracting similar pattern. However I do not how I can implement it!

[Ro Shu]

like this image in which similar patterns are clear

[Image Analyst]

The template does not have a position. It's just a template. Then normxcorr2 will find out where the template lives in the other, larger image. It will work for either of those two small templates you posted as long as they're the same size feature, and same orientation, in the larger image you're going to search.