Compared with other biometrics such as fingerprints and face, iris recognition has great advanta ge in uniqueness and stableness. It is reported by NPL that iris recognition has the highest recognition rate among the biometrics.
         Iris is an inner organ visible outside, so it can be captured without touch and is proof against the outer environment. Moreover, the experiments show that iris texture is stable over decades and even the two eyes of the same person or twins are greatly different. A sample of iris images is shown in the following figure, from which we can see that iris has rich texture that incurs the uniqueness of iris patterns.

　　An iris recognition system has two main parts: iris sensor (hardware) and iris recognition algorithm (software).
        The design of iris sensors is very important for the performance of the iris recognition system. Some sensors can be found on the homepages of the corporations.
        A classic iris recognition algorithm include image preprocessing, feature extraction, pattern matching and classifier design. The flow chart of the iris recognition system is shown in the following figure.

　　Some demonstrations can be downloaded    here