實現用按下鼠標左鍵拖動時，在鼠標經過的路徑上打上馬賽克。

馬賽克的原理是將圖像中選中區域的像素用這個選中區域中的某一像素覆蓋。

為了不讓鼠標重復經過圖像中同一個的時候，選取不一樣的像素，該程序將在輸入圖片的時候，就實現了全圖的馬賽克效果。而當鼠標劃過的時候，程序只是將實現馬賽克的圖片的指定位置復制到顯示的圖像中。效果類似于QQ截圖中的馬賽克。

#include <opencv2/core/core.hpp>#include <opencv2/highgui/highgui.hpp>#include <opencv2/imgPRoc/imgproc.hpp>#include <iostream>using namespace cv;using namespace std;Mat inputImage;Mat inputImage_mosaic;Mat inputImage_clone;//馬賽克的大小int neightbourhood = 20;//記錄鼠標的狀態，0為鼠標左鍵未按下或彈起，1為鼠標左鍵按下int mouseStatus = 0;void onMouse(int events, int x, int y, int flag, void* ustg);//創建馬賽克圖片void createMosaicImage(Mat inputMat, Mat& outputMat, int size);//設置馬賽克區域void setMosaic(Mat& inputMat, Rect rect);int main(void){	inputImage = imread("test2.jpg");	inputImage_clone = inputImage.clone();	createMosaicImage(inputImage, inputImage_mosaic, neightbourhood);	namedWindow("showImage", 0);	setMouseCallback("showImage", onMouse);	waitKey();	return 0;}void createMosaicImage(Mat inputMat, Mat& outputMat, int size){	RNG rng;	int height = inputMat.rows;	int width = inputMat.cols;	Mat padding;	Mat tempMat;	//為了方便后面的計算，將輸入的圖像大小擴充到寬高都是size的倍數	copyMakeBorder(inputMat, padding, 0, size - inputMat.rows % size, 0, size - inputMat.cols % size, BORDER_REPLICATE);	tempMat = padding.clone();		for (int row = 0; row < padding.rows; row += size){		for (int col = 0; col < padding.cols; col += size){			int rand_x = rng.uniform(0, size);			int rand_y = rng.uniform(0, size);			Rect rect = Rect(col, row, size, size);			Mat roi = tempMat(rect);			Scalar color = Scalar(padding.at<Vec3b>(row + rand_y, col + rand_x)[0], /				padding.at<Vec3b>(row + rand_y, col + rand_x)[1], /				padding.at<Vec3b>(row + rand_y, col + rand_x)[2]);			roi.setTo(color);		}	}	outputMat = tempMat(Rect(0, 0, width, height)).clone();}void setMosaic(Mat& inputMat, Rect rect){	Mat roi = inputMat(rect);	Mat tempRoi = inputImage_mosaic(rect);	tempRoi.copyTo(roi);}void onMouse(int events, int x, int y, int flag, void* ustg){	//當鼠標移除圖片區域的時候，不做操作	if (x < 0 || x > inputImage.cols || y < 0 || y > inputImage.rows){		return;	}	//馬賽克塊的位置信息	int x_left, x_right, y_top, y_bottom;	x - neightbourhood <= 0 ? x_left = 0 : x_left = x - neightbourhood;	x + neightbourhood > inputImage.cols ? x_right = inputImage.cols: x_right = x + neightbourhood;	y - neightbourhood <= 0 ? y_top = 0 : y_top = y - neightbourhood;	y + neightbourhood > inputImage.rows ? y_bottom = inputImage.rows: y_bottom = y + neightbourhood;	if (events == CV_EVENT_LBUTTONDOWN){		mouseStatus = 1;		setMosaic(inputImage_clone, Rect(x_left, y_top, x_right - x_left, y_bottom - y_top));	}	else if (events == CV_EVENT_MOUSEMOVE){		if (mouseStatus == 1){			setMosaic(inputImage_clone, Rect(x_left, y_top, x_right - x_left, y_bottom - y_top));		}		else{			//nothing		}	}	else if (events == CV_EVENT_LBUTTONUP){		mouseStatus = 0;	}	else {		//cout << "nothing" << endl;	}	imshow("showImage", inputImage_clone);}效果圖