Histogram equalization not working on color image - OpenCV

Question

I am trying to perform a histogram equalization using OpenCV using the following function

Mat Histogram::Equalization(const Mat& inputImage)
{
    if(inp         


        

Answer 1

I implemented a histogram equalization for BGRA image. I think this function is useful for your goal (but you should ignore the alpha channel).

Mat equalizeBGRA(const Mat& img)
{
Mat res(img.size(), img.type());
Mat imgB(img.size(), CV_8UC1);
Mat imgG(img.size(), CV_8UC1);
Mat imgR(img.size(), CV_8UC1);
Vec4b pixel;

if (img.channels() != 4)
{
    cout << "ERROR: image input is not a BGRA image!" << endl;
    return Mat();
}

for (int r = 0; r < img.rows; r++)
{
    for (int c = 0; c < img.cols; c++)
    {
        pixel = img.at(r, c);
        imgB.at(r, c) = pixel[0];
        imgG.at(r, c) = pixel[1];
        imgR.at(r, c) = pixel[2];
    }
}

equalizeHist(imgB, imgB);
equalizeHist(imgG, imgG);
equalizeHist(imgR, imgR);

for (int r = 0; r < img.rows; r++)
{
    for (int c = 0; c < img.cols; c++)
    {
        pixel = Vec4b(imgB.at(r, c), imgG.at(r, c), imgR.at(r, c), img.at(r, c)[3]);
        res.at(r, c) = pixel;
    }
}

return res;
}