problem with cv_bridge [closed]

asked 2013-11-27 21:38:24 -0600

Hamid Didari gravatar image

updated 2013-12-21 07:36:24 -0600

tfoote gravatar image

Hi dear I tried to follow cv_bridge example for this I ran cv_camera to get image from webcam and ran the example of cv_bridge but the example couldn't subscribe any message. the example program:

#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>

static const std::string OPENCV_WINDOW = "Image window";

class ImageConverter
  ros::NodeHandle nh_;
  image_transport::ImageTransport it_;
  image_transport::Subscriber image_sub_;
  image_transport::Publisher image_pub_;

    : it_(nh_)
    // Subscrive to input video feed and publish output video feed
    image_sub_ = it_.subscribe("/camera/image_raw", 100,
      &ImageConverter::imageCb, this);
    image_pub_ = it_.advertise("/image_converter/output_video", 1);



  void imageCb(const sensor_msgs::ImageConstPtr& msg)
      cv_bridge::CvImagePtr cv_ptr;
      cv_ptr = cv_bridge::toCvCopy(msg, sensor_msgs::image_encodings::BGR8);
    catch (cv_bridge::Exception& e)
      ROS_ERROR("cv_bridge exception: %s", e.what());

    // Draw an example circle on the video stream
    if (cv_ptr->image.rows > 60 && cv_ptr->image.cols > 60)
      cv::circle(cv_ptr->image, cv::Point(50, 50), 10, CV_RGB(255,0,0));

    // Update GUI Window
    cv::imshow(OPENCV_WINDOW, cv_ptr->image);

    // Output modified video stream

int main(int argc, char** argv)
  ros::init(argc, argv, "image_converter");
  ImageConverter ic;
  return 0;

could some one help me? I'm using ubuntu 12.10 and hydro

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Closed for the following reason question is not relevant or outdated by tfoote
close date 2014-11-23 13:56:19.218749


When you run cv_camera, does the topic "/camera/image_raw" show up when you do a "$rostopic list"?

Angus gravatar image Angus  ( 2013-11-28 17:22:28 -0600 )edit

yes,I subscribe the image in rviz

Hamid Didari gravatar image Hamid Didari  ( 2013-11-29 01:47:22 -0600 )edit

Did you troubleshoot with image_view?

TFinleyosu gravatar image TFinleyosu  ( 2014-02-11 12:11:24 -0600 )edit

I can subscribe image in rviz .but this program can't subscribe the image. I do not have output from my node. I try cv_bridge in another program work very well but this program doesn't work.

Hamid Didari gravatar image Hamid Didari  ( 2014-02-11 19:57:49 -0600 )edit