并用128灰度表示
class WatershedSegment{
private:
	cv::Mat markers;
public:
	void setMarkers(const cv::Mat &image){
		image.convertTo(markers,CV_32S);
	}
	cv::Mat process(const cv::Mat &image) {
		// Apply watershed
		cv::watershed(image,markers);
		markers.convertTo(markers,CV_8U);
		return markers;
	}
};
int _tmain(int argc, _TCHAR* argv[])
{
	cv::Mat image = cv::imread("group.jpg");
	cv::Mat binary = cv::imread("binary.bmp",0);  //没加0害得我找好久错误的原因。即使"binary.bmp"为二值图像不加0读进来还是3通道
	//cv::threshold(image,binary,60,255,CV_THRESH_BINARY);  //阈值化操作
	//binary = 255 - binary; //让前景变为白色区域
	cv::namedWindow("binary",CV_WINDOW_AUTOSIZE);
	cv::imshow("binary",binary);
	cv::Mat fImage;
	cv::erode(binary,fImage,cv::Mat(),cv::Point(-1,-1),6); //binary = 255 - binary; //让前景变为白色区域//腐蚀去掉小的干扰物体得到前景图像
	cv::namedWindow("eroded",CV_WINDOW_AUTOSIZE);
	cv::imshow("eroded",fImage);
	cv::Mat bImage;
	cv::dilate(binary,bImage,cv::Mat(),cv::Point(-1,-1),6);
	cv::threshold(bImage,bImage,1,128,cv::THRESH_BINARY_INV);//对原始二值图像阈值化并取反,得到背景图像
	cv::namedWindow("bImage",CV_WINDOW_AUTOSIZE);
	cv::imshow("bImage",bImage);
	cv::Mat marker(binary.size(),CV_8U,cv::Scalar(0));
	marker = fImage + bImage;  //创建标记图像
	cv::namedWindow("marker",CV_WINDOW_AUTOSIZE);
	cv::imshow("marker",marker);
	WatershedSegment segmenter;
	segmenter.setMarkers(marker);
	cv::Mat segment = segmenter.process(image);
	cv::namedWindow("segmenter",CV_WINDOW_AUTOSIZE);
	cv::imshow("segmenter",segment);
	cv::waitKey(0);
	return 0;
}
原文:http://www.cnblogs.com/mengfanrong/p/5189572.html