How does Hawk-Eye work?

It's every umpire's nightmare and every commentator's dream. Like it or not, Hawk-Eye is here to stay.

It first hit our screens in 2001 and has been helping to unravel the mysteries of the lbw decision ever since.

Hawk-Eye uses technology originally used for brain surgery and missile tracking.

It was invented by Dr Paul Hawkins, a former Buckinghamshire player.

It uses six specially placed cameras around the ground to track the path of the ball, from when it was released from the bowler's hand right up until when it's dead.

The images captured by the camera are then turned into a 3D image by a special computer to show how the ball will travel on an imaginary cricket pitch.

It can track any types of bounce, spin, swing and seam. And it is about 99.99% accurate.

But while TV viewers get to see the replay of an lbw decision several times, the umpires only get to see it once - and they have to make their minds up instantly.

Hawk-Eye has a couple of other useful features:

Because of the six cameras tracking the ball, Hawk-Eye picks up the exact spot where the ball pitches.

It can also create a "grouping" on a pitch to show exactly where a bowler has bowled to a batsman.

Hawk-eye also measures the speed of the ball from the bowler's hand, so it will tell you exactly how much time the batsman has to react to a ball.

The ECB has installed the Hawk-Eye system at the new Academy centre in Loughborough so both batsmen and bowlers can have their techniques analysed.