Advantages of the Iris for Identification
- Highly protected, internal organ of the eye
- Externally visible; patterns imaged from a distance
- Iris patterns possess a high degree of randomness
- variability: 244 degrees-of-freedom
- entropy: 3.2 bits per square-millimeter
- uniqueness: set by combinatorial complexity
- Changing pupil size confirms natural physiology
- Pre-natal morphogenesis (7th month of gestation)
- Limited genetic penetrance of iris patterns
- Patterns apparently stable throughout life
- Encoding and decision-making are tractable
- image analysis and encoding time: 30 milliseconds
- decidability index (d-prime): d' = 6 to 8 typically
- search speed: 1 million IrisCodes per second, with a 3 GHz CPU
Disadvantages of the Iris for Identification
- Small target (1 cm) to acquire from a distance (1 m)
- Moving target ...within another... on yet another
- Located behind a curved, wet, reflecting surface
- Obscured by eyelashes, lenses, reflections
- Partially occluded by eyelids, often drooping
- Deforms non-elastically as pupil changes size
- Illumination should not be visible or bright
- Some negative (Orwellian) connotations
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