使用这些位置的坐标向量访问和更改opencv中的多个像素

Question

我在c ++中的openCV中有一个Mat矩阵，我想通过以矢量形式提供行和列位置来更改此矩阵中的值。例如：

Mat M = Mat::zeros(10,10,CV_8UC1);
Mat IJ_coord = (Mat_<uchar>(3,2) << 0,0, 1,0, 2,7);
M.at<uchar>(IJ_coord) = 255;

有没有办法在不使用＆＃34; for＆＃34;周期太慢了？下面是代码。在进行一些初始化之前，为简单起见省略了。循环的最后一个是关键的。它们需要0.6秒，几乎是整个代码的一半时间。

int64 t0 = getTickCount();   



if (num_frame < 10){
prefix_num = "000";
} else if(num_frame < 100){
prefix_num = "00";
} else if(num_frame < 1000){
prefix_num = "0";
} else prefix_num = "";

string frame_num = to_string(num_frame);


Mat Point_w = readMatrix(folder_pnt_w + prefix_num + frame_num + ".txt",2);
Mat Point_I = readMatrix(folder_pnt_I + prefix_num + frame_num + ".txt",2);
I = imread(folder_frm + prefix_num + frame_num + ".jpg", 1);


split(I, planes);
I_ir = planes[2]-planes[1];




Mat H = findProjectiveTransformation(Point_I, Point_w);


addWeighted(i0, H.at<double>(0), j0, H.at<double>(1), H.at<double>(2), Num, 
-1);
addWeighted(i0, H.at<double>(6), j0, H.at<double>(7), 1, Den, -1);
divide(Num, Den, X_geo);
addWeighted(i0, H.at<double>(3), j0, H.at<double>(4), H.at<double>(5), Num, 
-1);
divide(Num, Den, Y_geo);

// here I will calculate the coordinates to access in the matrix

J_x_geo = (X_geo-X_min)/dx;
I_y_geo = (Y_max - Y_geo)/dy;

J_x_geo.convertTo(J_x_geo, CV_32S, 1, 0);
I_y_geo.convertTo(I_y_geo, CV_32S, 1, 0);



for(size_t i=0; i<I_ir.rows; i++){
for(size_t j=0; j<I_ir.cols; j++){




if (Y_geo.at<float>(i,j) >= Y_min && Y_geo.at<float>(i,j) <= Y_max && 
X_geo.at<float>(i,j) >= X_min && X_geo.at<float>(i,j) <= X_max){

if (Map.at<uchar>(I_y_geo.at<int>(i,j),J_x_geo.at<int>(i,j)) < I_ir.at<uchar>
(i,j)){

            Map.at<uchar>(I_y_geo.at<int>(i,j),J_x_geo.at<int>(i,j)) = 
            I_ir.at<uchar>(i,j);

         }
     }

}
}









int64 t1 = getTickCount();
double secs = (t1-t0)/getTickFrequency();

cout << secs << endl;