#include <opencv2/opencv.hpp>
#include <vector>

int main()
{
    cv::Mat3b image(cv::imread("lena3.png", cv::IMREAD_COLOR));
    if (image.empty()) {
        std::cerr << "Failed to load image.";
        return -1;
    }

    cv::Mat3b roi(image(cv::Rect(64, 128, 32, 32)));

    cv::Mat3d column_color_sums;
    cv::reduce(roi, column_color_sums, 0, cv::REDUCE_SUM);

    std::vector<double> column_sums(column_color_sums.cols, 0);
    cv::transform(column_color_sums, column_sums, cv::Matx13d(1, 1, 1));

    for (auto v : column_sums) {
        std::cout << v << " ";
    }
    std::cout << "\n";

    return 0;
}