Cycle through pixels with opencv

Question

How would I be able to cycle through an image using opencv as if it were a 2d array to get the rgb values of each pixel? Also, would a mat be preferable over an iplimage for

Answer 1

Since OpenCV 3.3 (see changelog) it is also possible to use C++11 style for loops:

// Example 1
Mat_ img = imread("lena.jpg");
for( auto& pixel: img ) {
    pixel[0] = gamma_lut[pixel[0]];
    pixel[1] = gamma_lut[pixel[1]];
    pixel[2] = gamma_lut[pixel[2]];
}

// Example 2
Mat_ img2 = imread("float_image.exr", cv::IMREAD_UNCHANGED);
for(auto& p : img2) p *= 2;