反向投影：
1 #include <opencv2/opencv.hpp> 2 #include <iostream> 3 4 using namespace cv; 5 using namespace std; 6 #define WINDOW_NAME "效果图" 7 8 Mat src, hsv, hue; 9 Mat temp, temp_hsv, temp_hue; 10 int bin = 30;//直方图组距 11 void on_BinChange(int, void*); 12 13 int main(int argc, char** argv) 14 { 15 src = imread("test.jpg"); 16 temp = imread("temp.jpg"); 17 if (src.empty()|| temp.empty()) { 18 printf("Could not load image..."); 19 return -1; 20 } 21 imshow("Input Image",src); 22 23 //转到HSV空间 24 cvtColor(src, hsv, COLOR_BGR2HSV); 25 cvtColor(temp, temp_hsv, COLOR_BGR2HSV); 26 27 //分离Hue色调通道 28 hue.create(hsv.size(),hsv.depth()); 29 temp_hue.create(temp_hsv.size(), temp_hsv.depth()); 30 int ch[]= {0,0}; 31 mixChannels(&hsv, 1, &hue, 1, ch, 1); 32 mixChannels(&temp_hsv, 1, &temp_hue, 1, ch, 1); 33 34 35 //创建Trackbar来输入bin的数目 36 namedWindow(WINDOW_NAME,WINDOW_AUTOSIZE); 37 createTrackbar("色调组距", WINDOW_NAME,&bin,180, on_BinChange); 38 39 //进行一次初始化 40 on_BinChange(0, 0); 41 42 imshow(WINDOW_NAME, src); 43 44 waitKey(0); 45 return 0; 46 } 47 48 void on_BinChange(int, void*) 49 { 50 //参数准备 51 MatND hist; 52 int histSize = max(bin, 2); 53 float hue_range[] = { 0,180 };//h通道的取值范围 54 const float* ranges = {hue_range}; 55 56 //计算直方图并归一化 57 //calcHist(&hue, 1, 0, Mat(), hist, 1, &histSize, &ranges, true, false); 58 //normalize(hist,hist,0,255,NORM_MINMAX,-1,Mat()); 59 calcHist(&temp_hue, 1, 0, Mat(), hist, 1, &histSize, &ranges, true, false); 60 normalize(hist, hist, 0, 255, NORM_MINMAX, -1, Mat()); 61 62 //计算反向投影 63 MatND backproj; 64 calcBackProject(&hue,1,0,hist,backproj,&ranges,1,true); 65 66 imshow("反向投影图", backproj); 67 68 //绘制直方图参数准备 69 int w = 400, h = 400; 70 int bin_w = cvRound((double)w/histSize); 71 Mat histImg = Mat::zeros(w,h,CV_8UC3); 72 73 //绘制直方图 74 for(int i=0;i<bin;i++) 75 { 76 rectangle(histImg, Point(i*bin_w,h),Point((i+1)*bin_w,h-cvRound(hist.at<float>(i)*h/255.0)),Scalar(100,123,255),-1); 77 } 78 79 imshow("直方图",histImg); 80 81 }
直方图反向投影可以在“输入图像”中 找到和“模板”直方图特征相似的部分。
