【ROS】cv_bridge使用与图像转换示例

// image_pub.cpp
#include <ros/ros.h>
#include <opencv2/opencv.hpp>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>

int main(int argc, char **argv)
{
    ros::init(argc, argv, "image_pub");
    ros::NodeHandle nh;
    image_transport::ImageTransport it(nh);
    image_transport::Publisher image_pub = it.advertise("camera/image", 1);

    // 打开视频文件
    cv::VideoCapture cap("../test.mp4");
    if (!cap.isOpened())
    {
        ROS_ERROR("Failed to open video file");
        return -1;
    }

    // 定义图像消息
    sensor_msgs::ImagePtr msg;

    ros::Rate loop_rate(30); // 发布频率为30Hz
    while (ros::ok())
    {
        cv::Mat frame;
        cap >> frame; // 读取视频帧

        if (frame.empty())
        {
            ROS_INFO("Video ended");
            break;
        }

        // 转换图像格式为ROS消息
        msg = cv_bridge::CvImage(std_msgs::Header(), "bgr8", frame).toImageMsg();

        // 发布图像消息
        image_pub.publish(msg);
        std::cout << "Published image" << std::endl;

        ros::spinOnce();
        loop_rate.sleep();
    }

    return 0;
}

cmake_minimum_required(VERSION 3.0.2)
project(image_pub)

## Compile as C++11, supported in ROS Kinetic and newer
add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS 
  roscpp 
  rospy
  std_msgs
  sensor_msgs
  image_transport
  cv_bridge
)

catkin_package(
  CATKIN_DEPENDS 
  roscpp 
  rospy 
  std_msgs 
  sensor_msgs 
  image_transport 
  cv_bridge
)

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
  include
  ${catkin_INCLUDE_DIRS}
)

add_executable(${PROJECT_NAME} src/image_pub.cpp)

## Specify libraries to link a library or executable target against
target_link_libraries(${PROJECT_NAME}
  ${catkin_LIBRARIES}
)

<?xml version="1.0"?>
<package format="2">
  <name>image_pub</name>
  <version>0.0.0</version>
  <description>The image_pub package</description>

  <!-- One maintainer tag required, multiple allowed, one person per tag -->
  <!-- Example:  -->
  <!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> -->
  <maintainer email="xxx@todo.todo">xxx</maintainer>


  <!-- One license tag required, multiple allowed, one license per tag -->
  <!-- Commonly used license strings: -->
  <!--   BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
  <license>TODO</license>

  <buildtool_depend>catkin</buildtool_depend>

  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>sensor_msgs</build_depend>
  <build_depend>image_transport</build_depend>
  <build_depend>cv_bridge</build_depend>

  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>
  <exec_depend>sensor_msgs</exec_depend>
  <exec_depend>image_transport</exec_depend>
  <exec_depend>cv_bridge</exec_depend>


  <!-- The export tag contains other, unspecified, tags -->
  <export>
    <!-- Other tools can request additional information be placed here -->

  </export>
</package>

// image_sub.cpp
#include <ros/ros.h>
#include <opencv2/opencv.hpp>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>

void imageCallback(const sensor_msgs::ImageConstPtr &msg)
{
    try
    {
        // 将ROS图像消息转换为OpenCV图像
        cv::Mat image = cv_bridge::toCvShare(msg, "bgr8")->image;

        // 显示图像
        cv::imshow("Image", image);
        cv::waitKey(1);
    }
    catch (cv_bridge::Exception &e)
    {
        ROS_ERROR("Failed to convert ROS image to OpenCV image: %s", e.what());
    }
}

int main(int argc, char **argv)
{
    ros::init(argc, argv, "image_sub");
    ros::NodeHandle nh;

    // 创建图像传输对象和订阅者
    image_transport::ImageTransport it(nh);
    image_transport::Subscriber sub = it.subscribe("camera/image", 1, imageCallback);

    // 创建opencv窗口本地显示
    cv::namedWindow("Image", cv::WINDOW_AUTOSIZE);
    
    ros::spin();

    cv::destroyAllWindows();

    return 0;
}

# 运行节点
catkin_make # 编译
source devel/setup.bash
rosrun image_pub image_pub # 发布
rosrun image_sub image_sub # 订阅