Thanks for the suggestion, I should have worded my question a bit more specific. It was more on the line of “Can stats be something other than cv::Mat” rather than “What is the type of matrix elements when stats is a cv::mat object” (which is covered in the docs as CV_32S). But I guess the suggested stats(label, COLUMN) acces to stats is to be understood as pseudocode and is worded like that in case matrix element access changes in some future release?