噪声的定义

• 椒盐噪声/salt-and-pepper noise
  
  • a type of noise in which some pixels are replaced by a white or a black pixel.
  • occur in faulty communication when the value of some pixels is lost during transmission.

void salt(Mat &image, int n) {
         for (int k=0; k<n; k++) {
             int i= rand()%image.cols;
             int j= rand()%image.rows;

             if (image.channels() == 1) { //gray-level image
             image.at<uchar>(j,i)= 255;
             } else if (image.channels() == 3) { //color image
             image.at<Vec3b>(j,i)[0]= 255;
             image.at<Vec3b)(j,i)[1]= 255;
             image.at<Vec3b>(j,i)[2]= 255;
             }
         }
     }