Iris Authentication Using Pupil Diameter Ratio for Accuracy

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Solution Overview

Problem

Iris recognition systems face challenges in maintaining accuracy under varying pupil diameters and increased database capacity and authentication time due to changes in light conditions and eyelid or lash concealment.

Innovation Solution

A personal authentication method using iris images that involves acquiring and registering feature data with a pupil opening degree index, allowing for accurate authentication regardless of pupil state through data retrieval and comparison, reducing false rejection rates and authentication time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the pupil diameter is adjusted by illumination before comparison, then the authentication accuracy is improved, but the authentication time increases

Engineering Contradiction:

Improveauthentication accuracyVSAvoidauthentication time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary extraction of iris feature amounts and creation of a reference database during the registration phase, before actual authentication occurs. This preliminary preparation allows the authentication phase to proceed quickly by simply comparing extracted features against pre-stored reference data, eliminating the need for time-consuming real-time pupil diameter adjustment and illumination control during authentication.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If multiple iris images with different pupil diameters are captured and registered, then the authentication accuracy under varying light conditions is improved, but the database capacity and authentication process time increase

Engineering Contradiction:

Improveauthentication accuracy under varying light conditionsVSAvoiddatabase capacity and process time

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system extracts and stores only the essential iris feature amounts (such as radial frequency components, angular frequency components, and their combinations) rather than storing multiple complete iris images with different pupil diameters. This extraction approach reduces database capacity requirements while maintaining the ability to authenticate accurately under varying light conditions, as the extracted features capture the essential iris patterns independent of pupil size.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses parameter transformations to convert iris images with different pupil diameters into a standardized feature representation space. By extracting features and normalizing them to account for pupil diameter variations, the system can compare iris images captured under different lighting conditions without requiring multiple separate registration databases, thus reducing complexity while maintaining adaptability.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If the iris pattern is expressed in polar coordinate system, then the authentication accuracy is maintained despite pupil diameter changes, but the false rejection rate increases slightly due to minor iris pattern changes

Engineering Contradiction:

Improveiris pattern stabilityVSAvoidfalse rejection rate

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The system combines multiple types of feature extraction methods (radial frequency components, angular frequency components, and their combinations) to create a comprehensive feature representation that is robust to both pupil diameter changes and minor iris pattern variations. This composite approach leverages the strengths of each individual feature extraction method while compensating for their individual weaknesses, thereby maintaining high authentication accuracy and reducing false rejection rates.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method provides robust and efficient iris authentication by accurately comparing feature data across varying pupil diameters, reducing false rejections and processing time, while maintaining a compact database.

Implementation Method 1

the iris expands and contracts in response to light in order to adjust the dimensions of the pupil

Methodology Applied

Scientific EffectPupil response to light: Photochromism

Data Source

PatentUS7796784B2Personal authentication method for certificating individual iris

Publication Date: 2010.09.14 PANASONIC HOLDINGS CORP

AI summary

A plurality of iris codes are registered for each registrant in an iris database (12) together with pupil diameter-iris diameter ratio R. At the time of authentication, an iris code is obtained from a captured iris image by feature extraction while pupil diameter-iris diameter ratio R is obtained. Ratio R obtained at the time of registration and ratio R obtained at the time of authentication are compared to specify an appropriate iris code from the iris database (12) as an item to be collated before authentication.