opencv图像遮掩及移动区域像素占比

#include "opencv2/opencv.hpp"
#include "opencv2/video/background_segm.hpp"

using namespace cv;
using namespace std;
int main()
{
	VideoCapture capture;
	capture.open(0);

	int frameNum = 1;
	Mat frame, mask, thresholdImage, output;
	if (!capture.isOpened())
		cout << "fail to open!" << endl;

	capture >> frame;
	Ptr bgsubtractor = createBackgroundSubtractorMOG2();
	bgsubtractor->setVarThreshold(20);

	while (true) {
		capture >> frame;
		++frameNum;

		// 视频遮挡
		//cv::Mat logo = cv::imread("mark.bmp");
		Mat logo(400, 300, CV_8UC3, Scalar(0, 0, 255));
		cv::Mat imageROI;
		int x = (frame.cols - logo.cols)/2;
		int y = frame.rows - logo.rows;
		imageROI = frame(cv::Rect(x, y, logo.cols, logo.rows));
		logo.copyTo(imageROI);
		cv::namedWindow("result");
		cv::imshow("result", frame);

		// 背景建模法提取前景mask
		//bgSubtractor(frame, mask, 0.001);
		bgsubtractor->apply(frame, mask, -1);

		// 计算黑白二值前景的非黑像素占比
		int nTotalPixel = 0;
		int nWhitePixel = 0;
		Mat_::iterator it = mask.begin();
		Mat_::iterator itend = mask.end();
		for (; it != itend; ++it)
		{
			nTotalPixel++;
			if ((*it)>0) nWhitePixel += 1;//二值化后，像素点是0或者255  
		}
		float fPercent = (nWhitePixel / (float)nTotalPixel) * 100;

		// 在图片中显示结果
		char text[64] = { 0 };
		sprintf(text, "%d/%d=%.4f", nWhitePixel, nTotalPixel, fPercent);
		cv::putText(mask, text, cv::Point(50, 60), cv::FONT_HERSHEY_SIMPLEX, 1, cv::Scalar(255, 23, 0), 2, 4);

		imshow("mask", mask);
		waitKey(10);
	}

	return 0;
}