opencv4 学习 17 模板匹配算法

算法步骤：

1. 加载原始图像
2. 加载模板图像
3. 使用模板图像作为滑动窗口与原始图像相应patch计算相似度。

#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>

using namespace cv;
using namespace std;

bool use_mask = false;
Mat img, templ, mask, result;
const char* image_window = "Source Image";
const char* result_window = "Result window";

int match_method;
int max_Trackbar = 5;

void matchingMethod(int, void*){
    Mat img_display;
    img.copyTo(img_display);

    int result_cols = img.cols - templ.cols + 1;
    int result_rows = img.rows - templ.rows + 1;

    result.create(result_rows, result_cols, CV_32FC1);

    bool method_accepts_mask = (TM_SQDIFF == match_method || match_method == TM_CCORR_NORMED);
    if(use_mask && method_accepts_mask){
        matchTemplate(img, templ, result, match_method, mask);
    }else{
        matchTemplate(img, templ, result, match_method);
    }
    normalize(result, result, 0, 1, NORM_MINMAX, -1, Mat());
    double minVal, maxVal;
    Point minLoc, maxLoc;
    Point matchLoc;

    minMaxLoc(result, &minVal, &maxVal, &minLoc, &maxLoc, Mat());

    if(match_method == TM_SQDIFF || match_method == TM_SQDIFF_NORMED){
        matchLoc = minLoc;
    }else{
        matchLoc = maxLoc;
    }
    rectangle(img_display, matchLoc, Point(matchLoc.x + templ.cols, matchLoc.y + templ.rows), Scalar::all(0), 2, 8, 0);
    rectangle(result, matchLoc, Point(matchLoc.x + templ.cols, matchLoc.y + templ.rows), Scalar::all(0), 2, 8, 0);

    imshow(image_window, img_display);
    imshow(result_window, result);

    return;
}


int main(int argc, char* argv[])
{
    img = imread("./Template_Matching_Original_Image.jpg", IMREAD_COLOR);
    templ = imread("./Template_Matching_Template_Image.jpg", IMREAD_COLOR);

    if(use_mask) mask = imread("mask.jpg", IMREAD_COLOR);

    namedWindow(image_window, WINDOW_AUTOSIZE);
    namedWindow(result_window, WINDOW_AUTOSIZE);

    const char* trackbar_label = "Method: \n 0: SQDIFF \n 1: SQDIFF_NORMED \n 2: TM_CCORR \n 3: TM_CCORR_NORMED \n "
                                 "4: TM_COEFF \n 5: TM_COEFF_NORMED";
    createTrackbar(trackbar_label, image_window, &match_method, max_Trackbar, matchingMethod);
    matchingMethod(0,0);

    waitKey(0);
    return 0;
}

参考：https://docs.opencv.org/3.4/de/da9/tutorial_template_matching.html