Introduction to Face Recognition

Face recognition is one of the many wonders that AI research has brought forward to the world. It is a subject of curiosity for many techies — who would like to have a basic understanding of how things work. Let us take a dip into the subject, to see how things work.

Intuition

To understand how a machine can recognize faces, we can start with asking ourselves — how do we recognize a face? Most images of human faces have two eyes, a nose, lips, forehead, chin, ears, hair… That rarely changes. Yet, faces are different from each other. What makes them different? At the same time, face of the same person changes with emotion, expression, age… In fact just change in orientation creates a different image. How do we identify a person in spite of all that?

On a gross level, one can say that there are some components of a face are related to age, emotion and orientation. While there are some other components that are stick to the person irrespective of the age, emotion, etc. Further, we can say that these components are not orthogonal or independent. We have all seen people who look alike sideways, but very different otherwise. Or, a kid in the family reminds people of his parents at that age, etc.

So, it is not so easy to logically identify these individual components. But, one can say that there are several…