OpenCV C++ -如何将每个像素的值替换为3x3邻域中灰度的平均值？

#include <opencv2/opencv.hpp>

cv::Mat image = cv::imread("image.jpg", cv::IMREAD_GRAYSCALE);

cv::Mat output = cv::Mat::zeros(image.size(), image.type());

for (int i = 1; i < image.rows - 1; i++) {
    for (int j = 1; j < image.cols - 1; j++) {
        int sum = 0;
        for (int k = -1; k <= 1; k++) {
            for (int l = -1; l <= 1; l++) {
                sum += image.at<uchar>(i + k, j + l);
            }
        }
        output.at<uchar>(i, j) = sum / 9;
    }
}

cv::imshow("Output", output);
cv::waitKey(0);