Access to each separate channel in OpenCV

Question

I have an image with 3 channels (img) and another one with a single channel (ch1).

    Mat img(5,5,CV_64FC3);     Mat ch1 (5,5,CV_64FC1); 

Is there any efficient way (not using for loop) to copy the first channel of img to ch1?

Answer 1

In fact, if you just want to copy one of the channels or split the color image in 3 different channels, CvSplit() is more appropriate (I mean simple to use).

Mat img(5,5,CV_64FC3); Mat ch1, ch2, ch3; // "channels" is a vector of 3 Mat arrays: vector<Mat> channels(3); // split img: split(img, channels); // get the channels (dont forget they follow BGR order in OpenCV) ch1 = channels[0]; ch2 = channels[1]; ch3 = channels[2];