In this section, we will see an example of using cv_bridge for acquiring images from a camera driver, and converting and processing the images using OpenCV APIs. Following is how the example works:

• Subscribe the images from the camera driver from the topic /usb_cam/image_raw (sensor_msgs/Image)
• Convert the ROS images to OpenCV image type using CvBridge
• Process the OpenCV image using its APIs and find the edges on the image
• Convert the OpenCV image type of edge detection to ROS image messages and publish into the topic /edge_detector/processed_image

The step by step procedure to build this example follows: