首先，我是参考这篇文章：
https://blog.csdn.net/u010925447/article/details/80033288
但是，消息转换并不成功：

cv::Mat image = cv::imread(argv[1], CV_LOAD_IMAGE_COLOR);
sensor_msgs::ImagePtr msg = cv_bridge::CvImage(std_msgs::Header(), "bgr8", image).toImageMsg();

所以，我又改成了这样：

    // ros 消息定义
    cv_bridge::CvImagePtr frame, frame1;
    frame = boost::make_shared< cv_bridge::CvImage >();
    frame->encoding = sensor_msgs::image_encodings::MONO8;
    frame->image = RefImg;
    frame1 = boost::make_shared< cv_bridge::CvImage >();
    frame1->encoding = sensor_msgs::image_encodings::BGR8;

     // publish
     frame1->image = pesudo_img;
     if( not frame->image.empty() || not frame1->image.empty())
     {
         frame->header.stamp = ros::Time::now();
         frame1->header.stamp = ros::Time::now();
         pub.publish( frame->toImageMsg() );
         pub1.publish( frame1->toImageMsg() );
     }
        
	// 订阅图像主题：原始图和深度图
	image_transport::ImageTransport it(n);
	image_transport::Subscriber sub2 = it.subscribe("camera/image", 1, imageCallback);

通过，上面操作才完成了图像消息发布与接收。

参考：
http://docs.ros.org/diamondback/api/cv_bridge/html/c++/classcv__bridge_1_1CvImage.html