cv::cuda::calcHist() giving zero array of length 256 as output

[cudawarped]

@Abinas_Chopdar

std::cout<<hist_gray_c.at<float>(i)<<std::endl;

The data type for the bins should be int not float. e.g.

for (int i = 0; i < 256; i++){ 
    std::cout<<hist_gray_c.at<int>(i)<<std::endl;
}

From the docs

hist Destination histogram with one row, 256 columns, and the CV_32SC1 type.