Scaling a matrix in OpenCV

问题

I have to process a matrix and then scale it as a gray scale image. In matlab I could achieve this using mat2gray function. How can I do the same in opencv?

for(int i=0;i<c4.rows-1;i++)
{
    for(int j=0;j<c4.cols-1;j++)
    {

        value=100*sin(2*pi*j*18.0/imgCols);
        c5.at<Vec2d>(i,j)=value;
    }
}

回答1:

#include <opencv2/imgproc/imgproc.hpp>

cv::Mat greyMat, colorMat;
cv::cvtColor(colorMat, greyMat, CV_BGR2GRAY);

回答2:

If you have already single channel matrices and want to scale their values between 0 and 1 (for displaying), try this one:

cv::Mat mat2gray(cv::Mat inMat)
{
    //idea: to be scaled between 0 and 1, compute for each value: val := (val - minVal)/(maxVal-minVal)

    if(inMat.channels() != 1) std::cout << "mat2gray only works for single channel floating point matrices" << std::endl;

    // here we assume floating point matrices (single/double precision both ok)
    double minVal, maxVal;

    cv::minMaxLoc(inMat, &minVal, &maxVal);

    cv::Mat scaledMat = inMat.clone();
    scaledMat = scaledMat - cv::Mat(inMat.size(), inMat.type(), cv::Scalar(minVal));
    scaledMat = ((1.0)/(maxVal-minVal))*scaledMat;

    return scaledMat;
}

来源：https://stackoverflow.com/questions/27483013/scaling-a-matrix-in-opencv