Next: The 256-Byte Iris Code Up: No Title Previous: Doubly Dimensionless Projected Polar
Next: The 256-Byte Iris Code Up: No Title Previous: Doubly Dimensionless Projected Polar
An uncompressed code length of 256 bytes was chosen because this is roughly the capacity of the three-channel magnetic stripe affixed to the reverse side of the standard IS-7811 credit/debit card [3]. But this absolute code length only establishes an upper bound on the information capacity of an iris code, and it is important to know its actual inherent capacity. This capacity is reduced by intrinsic correlations, if any, among the coding primitives themselves. It is then also important to know the ``source entropy" associated with the typical human iris signal, which will be much less than the upper bound determined by the resolution of imaging, because of inherent correlations (especially radial) within the iris. These reduced entropies directly influence the confidence levels associated with any decision strategy. In the methods to be described here, irises are efficiently recognized by executing a statistical test of independence on their codes. In effect, this examines whether the degree to which one iris code predicts another iris code, is compatible with the hypothesis that they arise from independent random processes. Such a test of statistical independence is passed almost certainly for two iris codes from different eyes, but the same test is failed almost certainly when the compared signatures originate from the same eye.