From Simple English Wikipedia, the free encyclopedia
Pixelation was used to hide this person's face

Pixelization is a way of hiding information from a picture. It is often used to censor pictures or movies that are inappropriate. It is also used to hide someone's face if they do not wish to be seen.

English Wiktionary
English Wiktionary
The English Wiktionary has dictionary definitions (meanings of a word) for: pixelization and pixelisation