Added README.md for image_tools - [Clean] (#596)

* Added README.md for image_tools with supplementary info in README.md for easier references.

Signed-off-by: Bey Hao Yun <[email protected]>

image_tools/README.md

@@ -0,0 +1,36 @@
+## **What Is This?**
+
+This demo provides simple utilities to connect to a workstation default camera device and display it in a window like below:
+
+![](img/result.png)
+
+## **Build**
+
+```bash
+colcon build --packages-select image_tools
+```
+
+## **Run**
+
+In `image_tools` ROS 2 package, two executables are provided, namely `cam2image` and `showimage` with different functions.
+
+## **1 - cam2image**
+Running this executable connects to your workstation's default camera device's video stream and publishes the images on '/image' and '/flipimage' topics using a ROS 2 publisher.
+
+```bash
+# Open new terminal
+ros2 run image_tools cam2image
+```
+
+Note that `cam2image` provides many useful command-line options. Run `ros2 run image_tools cam2image --help` to see the list of options available.
+>
+> Eg. If a camera device is not available, run `ros2 run image_tools cam2image --ros-args -p burger_mode:=true`.
+
+## **2 - showimage**
+Running this executable creates a ROS 2 node, `showimage`, which subscribes to the `sensor_msg/msg/Image` topic, `/image` and displays the images in a window.
+
+```bash
+# Open new terminal
+# Run showimage ROS 2 node to display the cam2image sensor_msg/msg/Image messages.
+ros2 run image_tools showimage
+```