OpenCV: How to calculate max(R,G,B)

c++, image, opencv

Solution

Your code will be much faster than this, but this is how to do it with split() and max():

Mat CalcRGBmax(Mat i_RGB)
{
    std::vector<cv::Mat> planes(3);
    cv::split(i_RGB, planes);
    return cv::Mat(cv::max(planes[2], cv::max(planes[1], planes[0])));
}

Problem

Sadly the OpenCV documentation has been written for mathematicians only or for those who already know how to use OpenCV. I want to do such a simple thing as getting the highest value of R,G,B for each pixel and write it to a new gray scale image. I tried `merge()`, `split()` and others but without success. The following function does exactly what I want, but I wonder if OpenCV could do that simpler. ``` Mat CalcRGBmax(Mat i_RGB) { if (i_RGB.channels() != 3) throw "24 bit color image expected."; Mat i_Gray(i_RGB.rows, i_RGB.cols, CV_8UC1); for (int Y=0; Y<i_RGB.rows; Y++) { BYTE* pu8_Src = i_RGB. ptr<BYTE>(Y); BYTE* pu8_Dst = i_Gray.ptr<BYTE>(Y); int P = 0; for (int X=0; X<i_RGB.cols; X++) { BYTE B = pu8_Src[P++]; BYTE G = pu8_Src[P++]; BYTE R = pu8_Src[P++]; pu8_Dst[X] = max(R, max(G,B)); } } return i_Gray; } ```

Original source