// opencv實現投影變換 // 2015 - 09 - 05 create by hym // 在屏幕上依次點四個點(左上->左下->右下->右上)，再點擊屏幕上任意一點即可#include <opencv2/core/core.hpp> #include <opencv2/highgui/highgui.hpp> #include "opencv2/imgproc/imgproc.hpp" #include "opencv2/calib3d/calib3d.hpp" #include <iostream> #include <limits> #include <numeric> using namespace cv; using namespace std;// We need 4 corresponding 2D points(x,y) to calculate homography. vector<Point2f> left_image; // Stores 4 points(x,y) of the logo image. Here the four points are 4 corners of image. vector<Point2f> right_image; // stores 4 points that the user clicks(mouse left click) in the main image.// Image containers for main and logo image Mat imageMain; Mat imageLogo;// Function to add main image and transformed logo image and show final output. // Icon image replaces the pixels of main image in this implementation. void showFinal(Mat src1, Mat src2) {Mat gray, gray_inv, src1final, src2final;cvtColor(src2, gray, CV_BGR2GRAY);threshold(gray, gray, 0, 255, CV_THRESH_BINARY);//adaptiveThreshold(gray,gray,255,ADAPTIVE_THRESH_MEAN_C,THRESH_BINARY,5,4);bitwise_not(gray, gray_inv);src1.copyTo(src1final, gray_inv);src2.copyTo(src2final, gray);Mat finalImage = src1final + src2final;namedWindow("output", WINDOW_AUTOSIZE);imshow("output", finalImage);cvWaitKey(0);}// Here we get four points from the user with left mouse clicks. // On 5th click we output the overlayed image. void on_mouse(int e, int x, int y, int d, void *ptr) {if (e == EVENT_LBUTTONDOWN){if (right_image.size() < 4){right_image.push_back(Point2f(float(x), float(y)));cout << x << " " << y << endl;}else{cout << " Calculating Homography " << endl;// Deactivate callbackcv::setMouseCallback("Display window", NULL, NULL);// once we get 4 corresponding points in both images calculate homography matrixMat H = findHomography(left_image, right_image, 0);Mat logoWarped;// Warp the logo image to change its perspectivewarpPerspective(imageLogo, logoWarped, H, imageMain.size());showFinal(imageMain, logoWarped);}} }int main(int argc, char** argv) {// We need tow argumemts. "Main image" and "logo image"/*if (argc != 3){cout << " Usage: error" << endl;return -1;}*/// Load images from arguments passed.imageMain = imread("pai.jpg");imageLogo = imread("2.3.jpg");// Push the 4 corners of the logo image as the 4 points for correspondence to calculate homography.left_image.push_back(Point2f(float(0), float(0)));left_image.push_back(Point2f(float(0), float(imageLogo.rows)));left_image.push_back(Point2f(float(imageLogo.cols), float(imageLogo.rows)));left_image.push_back(Point2f(float(imageLogo.cols), float(0)));namedWindow("Display window", WINDOW_AUTOSIZE);// Create a window for display.imshow("Display window", imageMain);setMouseCallback("Display window", on_mouse, NULL);// Press "Escape button" to exitwhile (1){int key = cvWaitKey(10);if (key == 27) break;}return 0; }

效果圖如下：

總結

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