C++ opencv模板匹配

1.模板匹配介绍

• 模板匹配就是在整个图像区域发现与给定子图像匹配的小块区域；
• 模板匹配需要首先给定一个模板图像；
• 另外需要一张待检测的图像；
• 工作方法：在待检测图像上，从左到右，从上到下计算模板图像与重叠子图像的匹配度，匹配程度越大，两者相同的可能性越大。

2.API 

matchTemplate

matchTemplate(
	InputArray image,	//原图像，必须是8-bit或者32-bit浮点数图像
	InputArray templ,	//模板图像，类型与输入图像一致
	OutputArray result,	//输出结果，必须是单通道32位浮点数，假设原图像W*H，模板图像w*h，结果必须为W-w+1，H-h+1的大小
	int method,			//使用的匹配方法
	InputArray mask=noArray()
	)
enum cv::TemplateMatchModes {
	cv::TM_SQDIFF = 0,
	cv::TM_SQDIFF_NORMED = 1,
	cv::TM_CCORR = 2,
	cv::TM_CCORR_NORMED = 3,
	cv::TM_CCOEFF = 4,
	cv::TM_CCOEFF_NORMED = 5
}

minMaxLoc(src, minVal, maxVal, minLoc, maxLoc, mask)
/*
在一个数组中找到全局最小值和全局最大值
minMaxLoc函数找到最小值和最大值元素值以及它们的位置。
*/

3.实例代码

#include 
#include 

#include 
using namespace std;
using namespace cv;

Mat src, temp, dst;
int match_method = TM_SQDIFF;
int max_track = 5;
const char* INPUT_T = "input image";
const char* OUTPUT_T = "result image";
const char* match_t = "template match-demo";
void Match_Demo(int, void*);
int main(int argc, char** argv) {
	// 待检测图像
	src = imread("D:/vcprojects/images/flower.png");
	// 模板图像
	temp = imread("D:/vcprojects/images/t2.png");
	if (src.empty() || temp.empty()) {
		printf("could not load image...\n");
		return -1;
	}
	namedWindow(INPUT_T, CV_WINDOW_AUTOSIZE);
	namedWindow(OUTPUT_T, CV_WINDOW_NORMAL);
	namedWindow(match_t, CV_WINDOW_AUTOSIZE);
	imshow(INPUT_T, temp);
	const char* trackbar_title = "Match Algo Type:";
	createTrackbar(trackbar_title, OUTPUT_T, &match_method, max_track, Match_Demo);
	Match_Demo(0, 0);

	waitKey(0);
	return 0;
}

void Match_Demo(int, void*) {
	int width = src.cols - temp.cols + 1;
	int height = src.rows - temp.rows + 1;
	Mat result(width, height, CV_32FC1);

	matchTemplate(src, temp, result, match_method, Mat());
	normalize(result, result, 0, 1, NORM_MINMAX, -1, Mat());

	Point minLoc;
	Point maxLoc;
	double min, max;
	src.copyTo(dst);
	Point temLoc;
	minMaxLoc(result, &min, &max, &minLoc, &maxLoc, Mat());
	if (match_method == TM_SQDIFF || match_method == TM_SQDIFF_NORMED) {
		temLoc = minLoc;
	} else {
		temLoc = maxLoc;
	}

	// 绘制矩形
	rectangle(dst, Rect(temLoc.x, temLoc.y, temp.cols, temp.rows), Scalar(0, 0, 255), 2, 8);
	rectangle(result, Rect(temLoc.x, temLoc.y, temp.cols, temp.rows), Scalar(0, 0, 255), 2, 8);
	
	imshow(OUTPUT_T, result);
	imshow(match_t, dst);
}