From sdk-wiki
It is sometimes convenient to view camera images outside of rviz.
1. cd to the ros_ws directory on the development workstation
$ cd ~/ros_ws
2. Initialize your environment
$ ./baxter.sh
For more details see Init your sdk environment
3. Run ros image_view on any available camera or image topic
$ rosrun image_view image_view image:=/cameras/left_hand_camera/image
The image:=</image/topic/here
is remapping the ~image parameter to the desired image topic.
For more information on using image_view, see the ROS wiki page.