In this section, we will show you a basic approach to detect faces in an image. We will use the cascade classifier in OpenCV to detect the face location. This approach may have alignment errors. In order to obtain a precise location, we will also provide another advanced approach to find the face region using facial landmarks. In our implementation, we will only use the face region. However, many researchers use facial landmarks to extract facial components, such as eyes and mouths, and operate on these components separately.