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opencvchannelmat

Multi-channel matrix/array

I've been reading about openCV recently and its cv::Mat data structure. In the documentation, the author keeps mentioning about multi-channel array and multi-channel matrix. Can some one give me a definition of those two, and what is a "channel"? I tried to find on google but found nothing similar.

Solution

  • The most basic example is a standard image. It has a width (cols), a height (rows) and 3 color channels. 

    Mat myImg = imread("color_picture.jpg");
Vec3b pixel = myImg.at<Vec3b>(y, x);

    In this case, myImg will be a CV_8UC3 -- 3 channels of 8 bit, unsigned integers.

    I prefer to use the templated class, because I feel it's more clear:

    Mat_<Vec3b> myImg = imread("color_picture.jpg");
// Or, Mat3b myImg = ...
Vec3b pixel = myImg(y, x);

    Then, pixel is Blue, Green, Red:

    uchar blue = pixel[0];