how to remove the rest of the image and only keep the circle And nest how to calculate its diameter ? I am working on iris recognition ? thanks in adavnce for your suggestions

Answer 1

[Image Analyst]

Call imfill() and then bwareaopen, and bwperim. It's like 3 lines of code.

[Image Analyst]

All right, here's the full demo, attached in blue below the image it produces. It calculates the area and ECD, Equivalent Circular Diameter. Let me know if you have any questions.

[lucky]

.

[Image Analyst]

Lucky, your outer "circle" is not even a circle. It's some arcs - not a complete circle but a broken up one. I just did what you asked - found the circle, the only one that was there. Even though I answered your question, it appears you are taking an entirely different approach. If I had known that initially I wouldn't have done this demo and would have referred you to published papers here that discuss how to find irises. Also, I added tags to the question so people know what it's really about. You can click on the iris tag to see other discussions on it if you want. Good luck on applying that algorithm to your images.

[lucky]

Thank you. Its becoming really useful to me... :)

Answer 2

[lucky]

Thanks for your response but I need the outer diameter. Diameter of the iris along the horizontal axis as the I am trying to follow the idea of http://www.matlabcodes.com/2011/01/iris-detection-matlab.html

and our next step will be to compare the two image....