"Machine vision" is a field of study and technology whose goal is to endow machines with the ability to perceive selective aspects of the world using visual means.

I apologize if this sounds like a circular definition. One can easily get lost in a particular concept or technology when trying to define machine vision. Perhaps it's best to start with a more ostensible definition, then. Those of us fortunate enough to have functional eyes have an incredible ability to perceive and understand the world through them. Engineers have long sought to endow machines with this same capability.

http://www.alexandria.nu/ai/machine_vision/introduction/