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.

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()

@quimnuss you can do something like

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

CvImagePtr img_ptr;

image.copyto(img_ptr->image);

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