Biometric entropy of iris and retina

eyeimaging, entropy, iris,  retina,biometrics, human recognition, security

Paper will be describing determination of the amount of entropy in biometriciris and retina for biometric purposes. In other words, it is a combination ofall possible occurrences minutia. Based on other experimental findings, formulais further modified and made it more precise.

Biometric identification systems have become a usual part ofrequirements for increasing security needs, also in strictly protected areassuch as nuclear plants, military facilities, and scientific laboratories;however they are used in common life as well. Iris or retina recognition is nota new idea but if we consider this as a multimodal system this gives us atotally different view to the security and reliability.

Biometric entropy describes the inherent variability in biometricsamples in the population. It can also be understood as the information contentof biometric samples is related to many questions in biometric technology. Forexample, one of the most common biometric questions is that of uniqueness. Sucha measure is important for the performance of biometric system, as a measure ofthe strength of biometric cryptosystems and for privacy measures. It also isrelevant for applications such as biometric fusion, where one would like toquantify the biometric information in each system individually, and the potentialgain from fusing the systems.

In our case the computation of the iris and retina biometric entropy isperformed in several ways, similar to fingerprints. We studied every pixel ofthe retinal image and checked whether there can be a split point of the vessels(bifurcation) or their termination (end point). Theoretically, we could saythat it can occur anywhere in each pixel. As we know from images and physics ofthe retinal blood vessels, it is not possible practically. So, if we assumethat in one pixel a bifurcation occurs, the next bifurcation can't be locatedin its close surroundings. Using this assumption, we can predict total numberof minutiae in one particular retinal image. For each occurrence, we rememberits properties (position in the image, the angle of the blood vessels, theminutiae type and the thickness of the blood vessels).

Practical calculation of the entropy from properties of the eye issimilar to the theoretical way. It is needed to find out the average occurrenceof features in the retina. That means bifurcations, vessels crossing andtermination. It will also depend on the image resolution and the quality of imagingsystems.