[ros-users] how to publish JPEG images with compressed_image_transport ?

[Rene Ladan]

Hi,

the attached C++ file publishes a JPEG picture from disk on
/jpeg/image/compressed
(verified with rostopic list -v).  However, if I run image_view to
display the picture, I only get
a blank window. There seems to be a discrepancy:

%rostopic list  -v

Published topics:
 * /rosout [roslib/Log] 2 publishers
 * /rosout_agg [roslib/Log] 1 publisher
 * /jpeg/image/compressed [sensor_msgs/CompressedImage] 1 publisher

Subscribed topics:
 * /time [unknown type] 3 subscribers
 * /rosout [roslib/Log] 1 subscriber
 * /clock [unknown type] 3 subscribers
 * /jpeg/image [unknown type] 1 subscriber

Comands invoked:
%roscore (with ROS_IP set to public IP address and ROS_MASTER_URI to
http://localhost:11311)
%rosrun pkg-name jpeg
%rosrun image_view image_view image:=/jpeg/image image_transport:=compressed

So there is probably something wrong with the code, but the unknown
type /jpeg/image in the
subscriber list also looks suspicious?

Regards,
Rene

2010/3/16 Jeremy Leibs <leibs at willowgarage.com>:
> 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 at 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/
>>
>> GPG fingerprint = E738 5471 D185 7013 0EE0  4FC8 3C1D 6F83 12E1 84F6
>> (subkeys.pgp.net)
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
> _______________________________________________
> ros-users mailing list
> ros-users at code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: jpeg.cpp
Type: text/x-c++src
Size: 1160 bytes
Desc: not available
URL: <http://lists.ros.org/pipermail/ros-users/attachments/20100326/c5ebebc1/attachment-0005.cpp>