Publishing an image from disk

edit

Here is my example that I got working in Hydro

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

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

    cv_bridge::CvImage cv_image;
    cv_image.image = cv::imread("/home/taylor/Pictures/face.jpg",CV_LOAD_IMAGE_COLOR);
    cv_image.encoding = "bgr8";
    sensor_msgs::Image ros_image;
    cv_image.toImageMsg(ros_image);

  ros::Publisher pub = nh.advertise<sensor_msgs::Image>("/static_image", 1);
  ros::Rate loop_rate(5);

  while (nh.ok()) 
  {
    pub.publish(ros_image);
    loop_rate.sleep();
  }
}

I've used the gscam driver to publish saved video files as a camera, and you can also use it to do snapshots, or really anything that gstreamer supports. You would be able to do what you want using this driver.

@quimnuss you can do something like

cv::Mat image; // fill in image with your image data

CvImagePtr img_ptr;

image.copyto(img_ptr->image);

link text

This takes an image file name from a command line and publishes at desired rate:

https://github.com/lucasw/vimjay/blob...

Making it take the filename from a rostopic could be nice.

#!/usr/bin/env python
# Lucas Walter
# GNU GPLv3
# Load an image from disk and publish it repeatedly

import cv2
import numpy as np
import rospy
import sys
from sensor_msgs.msg import Image

if __name__ == '__main__': 
    rospy.init_node('image_publish')

    name = sys.argv[1]
    image = cv2.imread(name)
    #cv2.imshow("im", image)
    #cv2.waitKey(5)

    hz = rospy.get_param("~rate", 1)
    rate = rospy.Rate(hz)

    pub = rospy.Publisher('image', Image, queue_size=1)

    msg = Image()
    msg.header.stamp = rospy.Time.now()
    msg.encoding = 'bgr8'
    msg.height = image.shape[0]
    msg.width = image.shape[1]
    msg.step = image.shape[1] * 3
    msg.data = image.tostring()
    pub.publish(msg)

    while not rospy.is_shutdown():
        pub.publish(msg)
        rate.sleep()