Why can't we smile in the passport photo?

You know you're not allowed to smile in the passport photo, but you're not even allowed to smile in other documents. What is the real reason?

The answer lies in international technology and security.

The main reason for stopping the smile is the introduction of software for facial recognition at airports and other border controls.

Many border points use computers instead of immigration officers to scan passports and photograph travelers.

Although people can easily recognize themselves despite facial expressions, cars need a little more help, writes Huff Post.

The algorithms don't work like us.

To match a 3D face with a passport photo 2D, they have to determine and measure facial features with accuracy.

This includes the distance between pupils, ears, nose, and mouth, the width of the eyes and the mouth, and many other characteristics.

Smile can make this more difficult because it changes the size of the face.