The OpenCV library is an extensive library aimed at providing real-time computer vision processing across multiple platforms. Essentially, if you want to do any serious image processing, object recognition, or analysis, then OpenCV is a perfect place to get started.
Fortunately, the latest release of OpenCV (version 3) has added support for interfacing via Python 3. Although performing real-time video processing can often require a computer with a powerful CPU, it will run on relativity limited devices such as the original Raspberry Pi (version 1). Using the more powerful Raspberry Pi 2 is highly recommended for the following recipes.
The concepts and underlying methods behind image and video processing can get rather complicated. This first recipe shall demonstrate how to work with OpenCV and most importantly provide an easy way to visualize various stages that may be used for processing images.