How to use OpenCV to find an area that is very different from the background in color?

Question

OpenCV

There is a sticker with a QR code on the printed circuit board, you need to cut out part of the image in order to transfer it to the recognition library. It seems that you need to use SimpleBlobDetector for this?

Answer 1

For example, because The QR code is a square - you can see it implemented in squares.cpp from the OpenCV examples.