• uvc_camera
• compressed_image_transport

These packages are initially installed in a ROS Desktop Package(ros-melodic-desktop or ros-melodic-desktop-full).

You need to install manually if you have installed ros-melodic-ros-base.

$ sudo apt install ros-melodic-uvc-camera
$ sudo apt install ros-melodic-compressed-image-transport

compressed_image_transport is required to publish compressed images. Compressed images are faster to send data through network than raw images.

NOTE: Make sure you run roscore in the other session.

The default device is /dev/video0. You can run the node with the camera /dev/video0 as follow:

$ rosrun uvc_camera uvc_camera_node

You can change the camera device with _device option.

$ rosrun uvc_camera uvc_camera_node _device:=/dev/video1

If you have installed compressed_image_transport, uvc_camera_node publishes compressed images automatically.

rqt_image_view is often used to see images published to a topic. Just run rqt_image_view.

$ rqt_image_view

• image_transport

$ sudo apt install ros-melodic-image-transport

The type of message between raw image and compressed image is different, and most nodes subscribe Image type as a source of image, so you have to republish compressed image to Image type if you utilize compressed image data.

$ rosrun image_transport republish <in_transport> <out_transport> in:=<in_base_topic> out:=<out_base_topic>

For example, suppose you are publishing images from a robot using the transport compressed and are subscribing Image type topic in another node. Your robot publishes /image_raw and /image_raw/compressed topics. The base topic of republished images must be different from /image_raw.

$ rosrun image_transport republish compressed raw in:=/image_raw out:=/image_repub

Note that <in_base_topic> must be the base topic(in this exapmle, /image_raw is a base topic), not the topic of compressed image topic itself(/image_raw/compressed).

<arg name="base_camera_image" default="/image_raw"/>
<arg name="image" default="/image_repub" />

<node name="image_republish" pkg="image_transport" type="republish" args="compressed raw">
    <remap from="in" to="$(arg base_camera_image)" />
    <remap from="out" to="$(arg image)" />
</node>