The ability to process human face information is important in many different software scenarios.
Well, I think that it is the 4th morning and I cannot see those veins any more.
This is typically used when the facial photo is captured off-angle and a zero-corrected fully frontal image 0 degrees pitch, yaw, and roll is required.
The greatest accuracy is possible when information is available from preserved soft tissue, from a portrait, or from a pathological condition or healed injury.