Opencv sum()[]
I am new to opencv , I do not understand the function "sum".
Mat img=(Mat_<double>(3,3)<<0,-1,0,-1,5,-1,2,-1,0); double rr=sum(img)[0]; cout<<"rr"<<rr<<endl;< p="">
waitKey(0);
return 0;
What is the meaning of this function "sum", sum(img)[0] is standing for?? sum(img)[1] is standing for ? sum(img)[2] is stranding for??