Question

I run a demo code from OpenCV 2.3, distrans.cpp and there is a line of code I barely figure out what it means:

Mat edge = gray >= edgeThresh, dist, labels, dist8u;

It is used like a thresholding operation but I don’t know how it works or even to name & google it.

Thanks

Answer 1

operator >= overload for cv::Mat maps the operation to call to cv::compare with the relevant comparison key.

The cv::compare function returns a mask (cv::Mat of CV_8U depth) where all elements satisfying the condition (if element of gray has a value not less than edgeThresh in your case) are set to 0xFF and the other elements are zero.