opencv-salt and pepper noise addition and removal

Common noise and its causes

Code

#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
using namespace std;
//添加椒盐噪声
Mat addSaltNoise(Mat srcImage, int n)
{
    
    
	Mat resultImage = srcImage.clone();
	for (int k = 0; k < n; k++)
	{
    
    
		//随机取行列值
		int i = rand() % resultImage.cols;		
		//%是求余运算，rand求随机数，一起是求0-图像列值之间的随机数
		int j = rand() % resultImage.rows;
 
		if (resultImage.channels() == 1) {
    
    
			resultImage.at<uchar>(j, i) = 255;
		}
		else
		{
    
    
			resultImage.at<Vec3b>(j, i)[0] = 255;
			resultImage.at<Vec3b>(j, i)[1] = 255;
			resultImage.at<Vec3b>(j, i)[2] = 255;
		}
		
	}
	return resultImage;
}
 
//均值滤波
Mat myAverage(Mat& srcImage)
{
    
    
	if (srcImage.channels() != 1) {
    
     cvtColor(srcImage, srcImage, COLOR_BGR2GRAY); }
	imshow("gray", srcImage);
	Mat dstImage = Mat::zeros(srcImage.size(), srcImage.type());
	//Mat mask = Mat::ones(3, 3, srcImage.type());
	
	for (int k = 1; k < srcImage.rows-1; k++) 
	{
    
    
		for (int n = 1; n < srcImage.cols - 1; n++) 
		{
    
    
			uchar f = 0;
			for (int i = -1; i <= 1; i++) 
			{
    
    
				for (int j = -1; j <= 1; j++) 
				{
    
    
					f += srcImage.at<uchar>(k + i, n + j);
					
				}
			}
			dstImage.at<uchar>(k, n) =uchar( f / 9);
		}
	}
	return dstImage;
}
 
//中值滤波
Mat myMedian(Mat& srcImage)
{
    
    
	Mat dstImage = srcImage.clone();
	//定义一个向量List
	vector<uchar>List;
	//遍历图像源
	for (int k = 1; k < srcImage.cols - 1; k++)
	{
    
    
		for (int n = 1; n < srcImage.rows - 1; n++) {
    
    
			
			//对模板窗口进行遍历
			for (int i = -1; i <= 1; i++)
			{
    
    
				for (int j = -1; j <= 1; j++)
				{
    
    
					//将窗口内的像素放进向量内
					List.push_back(srcImage.at<uchar>(n + j, k + i));
				}
			}
			//对窗内元素进行排序
			sort(List.begin(), List.end());
			//取向量的中间元素作为当前元素
			dstImage.at<uchar>(n, k) = List[5];
			//清除当前向量内的元素
			List.clear();
		}
	}
	return dstImage;
}
int main()
{
    
    
	Mat srcImage = imread("C:/Users/86176/Pictures/pics/house.jpg");
	if (srcImage.empty()) {
    
     printf("no image\n"); return -1; }
	Mat resultImage=addSaltNoise(srcImage, 5000);
	imshow("原图", srcImage);
	imshow("椒盐", resultImage);
	Mat dstImage = myAverage(resultImage);
	imshow("均值滤波", dstImage);
	Mat dst = myMedian(resultImage);
	imshow("中值滤波", dst);
 
	waitKey(0);
	return 0;
 
}
//

effect

Original image

Add salt and pepper noise

Mean filter

Median filter