利用OpenCV实现绿幕视频背景替换

	Mat bg = imread("background.jpg");  //背景图

	VideoCapture capture;  //读取待处理的绿幕视频
	capture.open("5.flv");
	if (!capture.isOpened())
	{
		cout << "Can not open video!" << endl;
		system("pause");
		return -1;
	}

	int width = capture.get(CAP_PROP_FRAME_WIDTH);
	int height = capture.get(CAP_PROP_FRAME_HEIGHT);

	resize(bg, bg, Size(width, height), 1, 1, INTER_CUBIC);  //将背景图resize成视频尺寸大小

cvtColor(frame, HSV, COLOR_BGR2HSV);   //将原图转换成HSV色彩空间

    //绿色HSV颜色分量范围
    int hmin = 35, smin = 43, vmin = 46; 
    int hmax = 77, smax = 255, vmax = 255;

        //经过inRange API处理，输出一张二值图像，即将前景从绿幕中扣出来啦
        inRange(HSV, Scalar(hmin, smin, vmin), Scalar(hmax, smax, vmax), mask);

Mat Replace_Background(Mat frame, Mat mask, Mat bg)
{
	Mat dst = Mat::zeros(frame.size(), frame.type());

	for (int i = 0; i < frame.rows; i++)
	{
		for (int j = 0; j < frame.cols; j++)
		{
			int p = mask.at<uchar>(i, j);  //传入的mask是张二值图,p为当前mask像素值

			if (p == 0)
			{   //代表mask此时为前景，将绿幕视频中的前景像素赋给dst
				dst.at<Vec3b>(i, j) = frame.at<Vec3b>(i, j);
			}
			else if (p == 255)
			{
				//代表mask此时为背景，将背景图像素赋给dst
				dst.at<Vec3b>(i, j) = bg.at<Vec3b>(i,j);
			}

		}
	}

	return dst;
}

#include<iOStream>
#include<opencv2/opencv.hpp>
using namespace std;
using namespace cv;


Mat Replace_Background(Mat frame, Mat mask, Mat bg)
{
	Mat dst = Mat::zeros(frame.size(), frame.type());

	for (int i = 0; i < frame.rows; i++)
	{
		for (int j = 0; j < frame.cols; j++)
		{
			int p = mask.at<uchar>(i, j);  //传入的mask是张二值图,p为当前mask像素值

			if (p == 0)
			{   //代表mask此时为前景，将绿幕视频中的前景像素赋给dst
				dst.at<Vec3b>(i, j) = frame.at<Vec3b>(i, j);
			}
			else if (p == 255)
			{
				//代表mask此时为背景，将背景图像素赋给dst
				dst.at<Vec3b>(i, j) = bg.at<Vec3b>(i,j);
			}

		}
	}

	return dst;
}

int main()
{

	Mat bg = imread("background.jpg");  //背景图

	VideoCapture capture;  //读取待处理的绿幕视频
	capture.open("5.flv");
	if (!capture.isOpened())
	{
		cout << "Can not open video!" << endl;
		system("pause");
		return -1;
	}

	int width = capture.get(CAP_PROP_FRAME_WIDTH);
	int height = capture.get(CAP_PROP_FRAME_HEIGHT);

	resize(bg, bg, Size(width, height), 1, 1, INTER_CUBIC);  //将背景图resize成视频尺寸大小

	Mat frame, HSV, mask, dst;
	//绿色HSV颜色分量范围
	int hmin = 35, smin = 43, vmin = 46; 
	int hmax = 77, smax = 255, vmax = 255;

	while (capture.read(frame))
	{

		cvtColor(frame, HSV, COLOR_BGR2HSV);   //将原图转换成HSV色彩空间

		//经过inRange API处理，输出一张二值图像，即将前景从绿幕中扣出来啦
		inRange(HSV, Scalar(hmin, smin, vmin), Scalar(hmax, smax, vmax), mask);

		dst = Replace_Background(frame, mask, bg);

		imshow("demo", frame);
		//imwrite("frame.jpg", frame);
		imshow("mask", mask);
		//imwrite("mask.jpg", mask);
		imshow("dst", dst);
		//imwrite("dst.jpg", dst);

		char key = waiTKEy(10);

		if (key == 27)
		{
			break;
		}
	}

	destroyAllwindows();
	capture.release();
	system("pause");
	return 0;
}