Detection of rectangular bright area in a Image using OpenCv

Question

I have previously asked a question Marking an interest point in an image using c++. I used the same solution and got the required point using the adaptive threshold and Blo

Answer 1

In the image shown above, I would suggest

1. either a normal thresholding operation which should work pretty well or

2. a line-wise chain-code "calculation" or

3. finding gradients in your histogram.

There would be plenty of other solutions. I would consider to subtract the background shading if this is consistent.