ROS Sensor_msgs/Image和OpenCV Mat互转

一、摘要

ROS 以自己的 sensor_msgs/Image 消息格式传递图像，但许多用户希望将图像与 OpenCV 结合使用。 CvBridge 是一个 ROS 库，提供 ROS 和 OpenCV 之间的接口。 CvBridge 可以在 vision_opencv 堆栈中的 cv_bridge 包中找到。

 二、干货

需要的头文件

1.  
   #include "ros/ros.h"
2.  
   #include <sensor_msgs/Image.h>
3.  
   #include <cv_bridge/cv_bridge.h>
4.  
   #include "opencv2/opencv.hpp"

A）cv::Mat 转 sensor_msgs::Image

1.  
   cv::Mat image;
2.  
   sensor_msgs::ImagePtr msg = cv_bridge::CvImage(std_msgs::Header(), "bgr8", image).toImageMsg();

B）sensor_msgs::Image 转 cv::Mat

1.  
   cv_bridge::CvImagePtr cv_ptr = cv_bridge::toCvCopy(msg, sensor_msgs::image_encodings::TYPE_8UC3);
2.  
   cv::Mat img = cv_ptr->image;

三、一个小Demo

1.  
   #include <ros/ros.h>
2.  
   #include <image_transport/image_transport.h>
3.  
   #include <cv_bridge/cv_bridge.h>
4.  
   #include <sensor_msgs/image_encodings.h>
5.  
   #include <opencv2/imgproc/imgproc.hpp>
6.  
   #include <opencv2/highgui/highgui.hpp>
7.  
    
8.  
   static const std::string OPENCV_WINDOW = "Image window";
9.  
    
10.  
    class ImageConverter
11.  
    {
12.  
    ros::NodeHandle nh_;
13.  
    image_transport::ImageTransport it_;
14.  
    image_transport::Subscriber image_sub_;
15.  
    image_transport::Publisher image_pub_;
16.  
     
17.  
    public:
18.  
    ImageConverter()
19.  
    : it_(nh_)
20.  
    {
21.  
    // Subscrive to input video feed and publish output video feed
22.  
    image_sub_ = it_.subscribe("/camera/image_raw", 1,
23.  
    &ImageConverter::imageCb, this);
24.  
    image_pub_ = it_.advertise("/image_converter/output_video", 1);
25.  
     
26.  
    cv::namedWindow(OPENCV_WINDOW);
27.  
    }
28.  
     
29.  
    ~ImageConverter()
30.  
    {
31.  
    cv::destroyWindow(OPENCV_WINDOW);
32.  
    }
33.  
     
34.  
    void imageCb(const sensor_msgs::ImageConstPtr& msg)
35.  
    {
36.  
    cv_bridge::CvImagePtr cv_ptr;
37.  
    try
38.  
    {
39.  
    cv_ptr = cv_bridge::toCvCopy(msg, sensor_msgs::image_encodings::BGR8);
40.  
    }
41.  
    catch (cv_bridge::Exception& e)
42.  
    {
43.  
    ROS_ERROR("cv_bridge exception: %s", e.what());
44.  
    return;
45.  
    }
46.  
     
47.  
    // Draw an example circle on the video stream
48.  
    if (cv_ptr->image.rows > 60 && cv_ptr->image.cols > 60)
49.  
    cv::circle(cv_ptr->image, cv::Point(50, 50), 10, CV_RGB(255,0,0));
50.  
     
51.  
    // Update GUI Window
52.  
    cv::imshow(OPENCV_WINDOW, cv_ptr->image);
53.  
    cv::waitKey(3);
54.  
     
55.  
    // Output modified video stream
56.  
    image_pub_.publish(cv_ptr->toImageMsg());
57.  
    }
58.  
    };
59.  
     
60.  
    int main(int argc, char** argv)
61.  
    {
62.  
    ros::init(argc, argv, "image_converter");
63.  
    ImageConverter ic;
64.  
    ros::spin();
65.  
    return 0;
66.  
    }

四、参考

cv_bridge/Tutorials/UsingCvBridgeToConvertBetweenROSImagesAndOpenCVImages - ROS Wiki

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