Bug in OpenCV2.3 cv::split() function. Identical values in all 3 channels

Question

After spending a couple of days trying figure out why opencv DFT would give 100% similar results for all three channels I ended up finding out that there might be a bug in the s

Answer 1

It is not a bug in OpenCV but there is a problem with your code.

The following line does not create a vector of 3 different Mats:

std::vector<cv::Mat> rgbChannels(3,cv::Mat(inputImage.size(),CV_64FC1));

Instead, this line produces a vector of 3 Mat headers sharing the same memory. It works this way because Mat copy constructor does not make a deep copy - it just increments an internal reference counter.

Just change your code to the following to solve your problem:

std::vector<cv::Mat> rgbChannels(3);
cv::split(inputImage, rgbChannels);