Most existing authentication systems start by detecting a face and trying to recognize it by matching it to a database of known people who use the system. This subsection will take a closer look at that. We will not dive into every single parameter of the software.
If you want more information about complete face detection and the recognition pipeline for both people and cats, then take a look at one of the PacktPub books called OpenCV for Secret Agents. It looks at the complete process in more detail.
If you want a very detailed explanation of the parameters used for the face detection interface in OpenCV based on the cascade classification pipeline from Viola and Jones, then I suggest going to Chapter 5, Generic Object Detection for Industrial Applications, which discusses the interface generalized for generic object detection.