
237Survey on Techniques Used in Iris Recognition Systems
where:
I(x, y) is the image of iris region
(x, y) are the Cartesian coordinates of origin
(r, θ) are the polar coordinates corresponding to standardized x
p
, y
p
x
1
, y
1
are the coordinates of the pupil and iris boundaries along the θ direction
The rubber sheet model takes account of pupil dilation and inconsistencies in size to
produce a normalized representation with constant dimensions.
In this way, the iris region is modeled by a exible rubber sheet anchored at the iris
boundary with the pupil center as the reference point. The normalized iris is shown in
Figure13.10.
Although the rubber sh ...