How to detect a red dot on the surface of the object?

Hello, I want to detect the red dot on the surface of an object and obtain the center coodinates of the dot.The radius of the dot is between 8 and 15. I used ‘imfindcircles’ function but it seems not to be very robust since it sometimes makes false detection. Is there any more robust method? Looking forward to some advice.

Answer 1

[Image Analyst]

See my color tracking app. It tracks green spots in an image. The video shows a green Sharpie marker moving and being tracked. Just modify it to find red instead of green.

[W Joey]

Thank you for your reply. I have read your code but i don't quite understand every steps you take. Could you please simplify the code? I just want to draw a circle around the red dot and get the x and y coodinates of the dot center.

[Image Analyst]

But nearly every line of code has a comment to explain it. What lines need simplifying or explaining?

Can you upload your video or a frame from it? Is your lighting and red spot brightness constant or does it change from frame to frame?

[W Joey]

The spot brightness is constant and it should be detected from an image only. Here is the image. I want to detect and obtain the location of the red spot on the surface of the phone.

[Image Analyst]

Is everything in the field of view still except the spot? If so, you might be able to subtract sequential frames, like in my attached demo, to detect what is different from frame to frame. Your spot is not very red and there are other things in the frame of that color so you might have to also take size, shape, and location into your segmentation algorithm.