The RGB vectors for white and red color are same for this image (Matlab)

I was working with this picture in Matlab to detect color of the circles. This is a 512 by 512 jpeg image.

I am finding the centers of circles using imfindcircles, then I am taking the R,G,B components of some points near center of each circle to detect color.

But, I am confused because for both the red and white circles, I find that the R, G, B components are same [239 227 175].

I am new to image processing, so can anyone explain what's actually happening here.

Answer 1

[Jan]

[239, 227, 175] is the color of the background. I guess boldly that you have confused X and Y components of the coordinates.

The red dot has the color [237, 27, 36], the black dot [0, 0, 0] and the white dot is [255, 255, 255].

The problem might get clear, if you post the relevant part of your code.

[Zabir Al Nazi Nabil]

Here's my code Code

[Zabir Al Nazi Nabil]

I think I am getting the background components for red and white circles.

[Zabir Al Nazi Nabil]

I have found the problem, I was rounding the center coordinates using uint8 which was causing an overflow.

[Image Analyst]

If the image has more than 255 rows or columns, it will clip it to 255 so you couldn't examine any pixels further out. You should have used round() instead of uint8() and then it would be a double but still an integer and you would not have had the problem.