The axis_camera node in the texas_drivers stack does exactly this.

https://code.ros.org/trac/wg-ros-pkg/browser/stacks/texas_drivers/trunk/axis_camera/axis.py

The relevant snippets (python code, but C++ would be almost identical):

Create the appropriate publishers ("compressed" and "camera_info"

    self.pub = rospy.Publisher("axis_camera/compressed", CompressedImage, self)
    self.caminfo_pub = rospy.Publisher("axis_camera/camera_info",
CameraInfo, self)



Populate the appropriate messages and publish:

      img = fp.read(content_length)

      msg = CompressedImage()
      msg.header.stamp = rospy.Time.now()
      msg.format = "jpeg"
      msg.data = img

      self.axis.pub.publish(msg)

      cimsg = CameraInfo()
      cimsg.header.stamp = msg.header.stamp
      cimsg.width = self.width
      cimsg.height = self.height

      self.axis.caminfo_pub.publish(cimsg)


On Tue, Mar 16, 2010 at 7:10 AM, Rene Ladan <r.c.ladan@gmail.com> wrote:
> Hi,
>
> I'm writing a node to publish images from the Surveyor stereo camera
> (see http://www.surveyor.com/stereo/ ).
> The camera publishes the images in JPEG format.  The logical thing
> would be to somehow feed them to the
> compressed_image_format node (after setting up a handmade header?) to
> publish them.  Is there any example
> code which does this?
>
> Also, if I understand correctly, the subscriber can just subscribe to
> the normal image_transport topic, but needs
> to have extra code to decompress compressed images before using them?
>
> Thanks,
> Rene
> --
> http://www.rene-ladan.nl/
>
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