用光流场方法,标出前景(运动)和背景(静止)。
环境:VS2017 + OpenCV3.4.1
光流场介绍可以参见英文版学习OpenCV3的第17章Tracking
英文原版学习OpenCV3下载链接
https://download.csdn.net/download/iefenghao/11194776
视频测试
步骤
(1)打开视频
(2)转为灰度图
(3)光流检测,标出前景
#include <iostream> #include "opencv2/opencv.hpp" using namespace cv; using namespace std; #define UNKNOWN_FLOW_THRESH 1e9 void makecolorwheel(vector<Scalar> &colorwheel) { int RY = 15; int YG = 6; int GC = 4; int CB = 11; int BM = 13; int MR = 6; int i; for (i = 0; i < RY; i++) colorwheel.push_back(Scalar(255, 255 * i / RY, 0)); for (i = 0; i < YG; i++) colorwheel.push_back(Scalar(255 - 255 * i / YG, 255, 0)); for (i = 0; i < GC; i++) colorwheel.push_back(Scalar(0, 255, 255 * i / GC)); for (i = 0; i < CB; i++) colorwheel.push_back(Scalar(0, 255 - 255 * i / CB, 255)); for (i = 0; i < BM; i++) colorwheel.push_back(Scalar(255 * i / BM, 0, 255)); for (i = 0; i < MR; i++) colorwheel.push_back(Scalar(255, 0, 255 - 255 * i / MR)); } void motionToColor(Mat flow, Mat &color) { if (color.empty()) color.create(flow.rows, flow.cols, CV_8UC3); static vector<Scalar> colorwheel; //Scalar r,g,b if (colorwheel.empty()) makecolorwheel(colorwheel); // determine motion range: float maxrad = -1; // Find max flow to normalize fx and fy for (int i = 0; i < flow.rows; ++i) { for (int j = 0; j < flow.cols; ++j) { Vec2f flow_at_point = flow.at<Vec2f>(i, j); float fx = flow_at_point[0]; float fy = flow_at_point[1]; if ((fabs(fx) > UNKNOWN_FLOW_THRESH) || (fabs(fy) > UNKNOWN_FLOW_THRESH)) continue; float rad = sqrt(fx * fx + fy * fy); maxrad = maxrad > rad ? maxrad : rad; } } for (int i = 0; i < flow.rows; ++i) { for (int j = 0; j < flow.cols; ++j) { uchar *data = color.data + color.step[0] * i + color.step[1] * j; Vec2f flow_at_point = flow.at<Vec2f>(i, j); float fx = flow_at_point[0] / maxrad; float fy = flow_at_point[1] / maxrad; if ((fabs(fx) > UNKNOWN_FLOW_THRESH) || (fabs(fy) > UNKNOWN_FLOW_THRESH)) { data[0] = data[1] = data[2] = 0; continue; } float rad = sqrt(fx * fx + fy * fy); float angle = atan2(-fy, -fx) / CV_PI; float fk = (angle + 1.0) / 2.0 * (colorwheel.size() - 1); int k0 = (int)fk; int k1 = (k0 + 1) % colorwheel.size(); float f = fk - k0; //f = 0; // uncomment to see original color wheel for (int b = 0; b < 3; b++) { float col0 = colorwheel[k0][b] / 255.0; float col1 = colorwheel[k1][b] / 255.0; float col = (1 - f) * col0 + f * col1; if (rad <= 1) col = 1 - rad * (1 - col); // increase saturation with radius else col *= .75; // out of range data[2 - b] = (int)(255.0 * col); } } } } int main(int, char**) { VideoCapture cap; //cap.open(0); cap.open("srcVideo.mp4"); if (!cap.isOpened()) return -1; Mat prevgray, gray, flow, cflow, frame; Mat motion2color; for (;;) { double t = (double)cvGetTickCount(); cap >> frame; cvtColor(frame, gray, CV_BGR2GRAY); imshow("src 1210", frame); if (prevgray.data) { calcOpticalFlowFarneback(prevgray, gray, flow, 0.5, 3, 15, 3, 5, 1.2, 0); motionToColor(flow, motion2color); imshow("dst 1210", motion2color); } if (waitKey(10) >= 0) break; std::swap(prevgray, gray); t = (double)cvGetTickCount() - t; cout << "cost time: " << t / ((double)cvGetTickFrequency()*1000.) << endl; } return 0; }