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Iris Recognition Anders Hur COEN 150 Holliday 2-22-05 The attacks of September 11th, 2001 demonstrated the immediate need for improved security in our society. People around the world realized that what they thought was safe and secure was in fact vulnerable and in danger. At no other time in history has there been such a desperate call for security. In the scramble to implement better security came the realization of new solutions. One such solution was biometrics. Biometrics is the recognition of a person based on physiological or behavioral characteristics1. The most commonly known biometric is the fingerprint. It was perceived as a method of identification in the1800’s and has since been the main biometric used in modern society. Other biometrics include voice patterns, facial recognition, and retinal and iris scanning. Of these, iris scanning, also known as iris recognition, has become accepted by many as a superior method of identification. History One of the first applications of iris analysis was Iridology. Starting in the 1800’s, Iridology was the belief that parts of the body were represented by corresponding areas in the iris. According to this belief, analysis of the color and texture of the iris could lead to diagnosis of a person’s health and diseases. Iridology also implies that the iris changes over time depending on the health of a person. However, all these beliefs have been proven groundless. Multiple studies have shown that iridologists cannot accurately diagnose a person’s well- 1 findBiometrics.com. “What are Biometrics?” 18 February 2005 <http://www.findbiometrics.com/Pages/guide1.html>. being2. Nevertheless, iridologists still practice and people still consult with them about health. Alphonse Bertillon was the first to study eye color as a means of identification. Frank Burch expanded this claim at a meeting of the American Academy of Ophthalmology in 1936. He claimed that the complex patterns in the iris could be used as an optical fingerprint. This idea became accepted in the field but was not realized for decades until two ophthalmologists named Leonard Flom and Aran Safir patented it in 1987. They then went to John Daugman for help with the algorithm and mathematical theory necessary for automated iris recognition. In 1994 Daugman patented a method for iris reading, analysis, and comparison3. These patents are held by Iriscan Inc. which is now Iridian Technologies. Another major contributor to iris recognition is Richard Wildes. His method of iris reading, analysis and matching differ from that of Daugman’s. Anatomy of the Iris The iris is the colored part of the eye. The function of the iris is to control the amount of light that enters the eye. It has tiny muscles that allow it to dilate and constrict the size of the pupil for light regulation. It is flat and separates the front and back of the eye4. It is protected in the front of the eye by the cornea. 2 Barrett, Stephen. “Iridology is Nonsense.” Quackwatch. 10 September 2004. 18 February 2005 <http://www.quackwatch.org/01QuackeryRelatedTopics/iridology.html>. 3 Daugman, John. “Iris Recognition.” August 2004. 18 February 2005 <http://www.securimetrics.com/articles/gfx/Iris_PDF_file.pdf>. 4 “Iris.” StLukesEye.com. 18 February 2005 <http://www.stlukeseye.com/anatomy/Iris.asp>. The basic structure of the iris is genetically determined. However, the exact composition of the iris is based on the conditions in the embryo during development and is thus very unique. In rare cases, the iris develops abnormally. Some parts of the iris are defined at birth but other parts do not solidify until about two years of age. In addition, the iris size and coloring continue to develop until adolescence. The iris changes very little after adolescence with the exception of depigmentation and a decrease in size of the pupil in advanced age5. It is necessary to delve into the structure of the iris in order to realize its uniqueness. It is made up of four different layers. The back layer is heavily pigmented and makes the iris opaque so that light only reaches the eye through the pupil. The next layer out contains the sphincter and dilator muscles that allow for constriction and dilation. The third layer is the stromal layer which, “consists of collagenous connective tissue in arch-like processes6.” In this layer are corkscrew-like blood vessels that span out radially. The exterior layer is called the “anterior border layer” and is denser than the previous layer with more pigmentation. The color of the iris is created by different levels of light absorption in the anterior border layer. Little pigmentation in this layer results in a blue appearance because light reflects from the back layer of the iris. The more 5 Wildes, Richard P. “Iris Recognition: An Emerging Biometric Technology.” 18 February 2005 <http://www.cs.yorku.ca/~wildes/wildesPIEEE1997.pdf>, 1349. 6 Ibid. 1348. pigmentation a person has in the anterior border layer, the darker their iris is. The overall visual appearance of the iris is due to its multi-layered structure7. Why Iris Recognition? There are many different biometrics to use for identification. What makes iris recognition better than other biometrics? To begin with, the iris is an internal organ of the eye. This means that the iris is protected from the external environment because it is situated behind the cornea and aqueous humor. Although the iris is an internal organ, it is still externally visible and can be read at reasonable distances. The irises of a person are also very unique. The basic structure and color of the iris is determined genetically, but the minute details of the iris are created based on conditions in the embryo8. The chances of similar irises are 1 in 1078 9. Even identical twins have different irises because of the randomness of creation in the embryo10. In fact, the left and right irises of the same person are different. Iris patterns have also been shown to be stable for the life of an individual (the exceptions being preadolescence and advanced age). This means that only one initial enrollment reading needs to be taken. Thereafter, no more readings are necessary because of the stability of the iris. This eliminates extra time spent updating that is often required for other biometrics. 7 Ibid. 1348. 8 Ibid. 1349. 9 LG Electronics. “How it Compares.” Iris Technology Division. 18 February 2005 <http://www.lgiris.com/iris/compares.html>. 10 Daugman, John. “Genetic penetrance and iris recognition.” 18 February 2005 <http://www.cl.cam.ac.uk/users/jgd1000/genetics.html>. The nature of the iris also helps in detecting frauds. It is impossible to surgically modify the iris without unacceptable risk to vision because it is located behind the cornea and aqueous humor. The iris’s physiological response to light also prevents the use of paper imitations or even removed eyes11. A simple addition or reduction of light to the eye can determine if an iris is living or not. These two characteristics of the eye and iris make iris recognition very hard to falsify or change. How Iris Recognition Works The basic procedure for iris recognition is the same for most products. The first phase is enrollment. A person is taken to a controlled and monitored environment in which their identity is manually confirmed. Once their identity is confirmed one or both of their irises are recorded, depending on the system used. During the image acquisition stage irises are recorded using black and white video cameras (they are not “scanned” as the common term “iris scan” suggests). The recorded image then goes through iris localization. In this stage a computer takes the recorded image and filters out everything but the iris. The localization process is done through complex algorithms which eliminates eyebrows, eyelashes, and the sclera (the white part of the eyes). Once the pictures are localized they are stored in a binary format. 11 Daugman, John. “High Confidence Visual Recognition of Persons by Test of Statistical Independence.” 18 February 2005 <http://www.cl.cam.ac.uk/users/jgd1000/PAMI93.pdf>. The last stage of iris recognition occurs after the enrollment process. Once a person has been enrolled they can proceed to an iris recognition unit. At the recognition unit, the iris is recorded and the two steps from enrollment are processed. An additional pattern matching step is required in the recognition phase. In the pattern matching stage the localized iris picture is compared with other irises in the database. If a match is found a desired outcome such as opening a door or granting access to a computer is achieved. Challenges and Solutions in Iris Recognition Although the steps of iris recognition sound straight forward, the actual details of how each step is achieved is very complex. This section details the challenges in iris recognition and then provides the solutions that two main iris recognition technologies use. The first of these iris recognition technologies was created by John Daugman in 1994. The other was by Richard Wildes in 199812. The Daugman technology is the more widely used of the two. The first challenge of iris recognition is to get a high-resolution image of an iris while at the same time being noninvasive. This is a challenge because the iris is small (about 1cm in diameter) and dark, combined with the fact that human users are sensitive to intense light. There needs to be enough light in order to get a high quality reading with enough detail and contrast. However, iris recognition methods cannot shine too much light on the iris because humans are sensitive to light. 12 LG Electronics. “How it Works.” 18 February 2005 <http://publib.upol.cz/~obd/fulltext/Physica%2039/Physica%2039_07.pdf>. The Daugman system solves the resolution problem by getting video images of the iris that have 100 to 200 pixels in diameter from a distance of 15- 46 cm. It also solves the light issue by using a LED light source and a normal video camera. This method results in a compact design and also allows for the use of glasses because the LED does not reflect on the glasses. However, because the LED is located below the user, a refection is captured on the lower portion of the iris. This means that a portion of the lower iris must be omitted during matching because it is affected by glare13. The Wildes system uses a low-light camera to capture about 256 pixels for the diameter of the iris from 20cm away. It uses a more complex method of lighting but in the process reduces glare. This is done by using circular polarization which blocks reflecting light but allows normal (diffused) light to penetrate the polarization. The reduced glare in this method allows for more detail to be recorded and compared which results in a higher level of security14. Another problem in image acquisition is to get the iris in the right position so that it can be recorded without requiring invasive contact (such as a eye piece or chin rest). The Daugman system allows for this by using a small LCD screen to show the user what is being captured. The LCD is placed directly behind a mirror that captures the iris image. In this way, the user can see exactly what the camera sees and adjust accordingly. While the user is adjusting the video camera takes continuous footage until a sufficient image is obtained15. 13 Wildes, 1353. 14 Ibid. 1353. 15 Ibid. 1353. The Wildes system uses a more low-tech method of positioning the iris. In this system, a square outline is centered around the camera lens. Another smaller square outline is also suspended in front of the lens. These squares are situated so that a user is in the right position when the squares overlap. Once the user overlaps the squares, he or she pushes a button to have the camera take a picture. One disadvantage of the Wildes system is that it uses a still camera for image acquisition and thus may require multiple recordings in order to obtain a good image16. The iris localization stage also creates problems for iris recognition technologies. Localization is the term used for editing an image to contain information only pertaining to the iris. Localization is needed because an image taken by an iris recognition unit contains not only the iris but also the areas surrounding it. These extra parts include the pupil, eyelashes, eyelids and the sclera (the white of the eyes). Difficulties arise when trying to separate these parts from the iris. The sclera is the easiest part to differentiate because of the distinct difference between the white sclera and the darker iris. It becomes much more difficult to distinguish between the pupil and the iris, especially when the iris is a very dark brown. It is can also be hard to distinguish between the eyelid and the iris because of both skin tone and the irregularity of the eyelid border due to eyelashes. The Daugman and Wildes systems use similar methods in distinguishing the iris from its surrounding area. The first way that these systems separate the 16 Ibid. 1353. regions is by using first derivatives. The derivatives are used to find the change in color between two points. The greater the change, the more likely that there is a line between two different parts of the eye17. The second way that these systems distinguish regions is through modeling. Both systems use modeling but in slightly different ways. The Daugman system eliminates the upper and lower part of the image where eyelids are expected to be. It also eliminates part of the iris portion where a glare is expected to be from the LED. In contrast, the Wildes system explicitly models the top and bottom portions of the image with parabolic curves so as to include as much of the iris as possible. The exact mathematical differences in the modeling are beyond the scope of this paper. The Wildes method ends up produces a more complete image of the eye for better pattern matching but at the same time requires more computation to achieve its result18. The third and final stage of iris recognition is pattern mapping. Within pattern mapping are four subcategories; alignment, representation, goodness of match, and decision. Alignment is the process in which an image of an iris is put into spatial alignment so that it can be compared to other iris images. Representation is the way in which iris patterns are represented in order to allow for distinction between irises. The differences between the Daugman and Wildes systems for the above two subcategories cannot be expressed in this paper because of the complexity of the mathematics involved. Goodness of match is the method in which irises are compared. The Daugman system compares irises 17 Ibid. 1354. 18 Ibid. 1354-1355. by taking the binary representation of the iris and XOR’s the bits with corresponding bits of the comparing iris. The Wildes system once uses complex mathematical calculations to compare irises. The final subcategory is the decision of whether two irises are from the same person or not. This again involves mathematics that are beyond the scope of this paper and thus cannot be compared19. Both the Daugman and Wildes systems have been tested. The Daugman system takes under 1 second to complete both the enrolment and verification processes. The Daugman system also has an identification mode which allows for a comparison to the complete database (as opposed to verification which only compares to a specified database). The identification mode of Daugman’s system takes 1 second for every 4000 entries compared20. The Daugman system was tested twice. The first test involved 592 recorded irises from 323 people (each person’s iris was recorded more than once). In this test, the crossover rate for false accepts and false rejects was 1 in 131,000. A conditional false reject rate of 1 in 109.6 was found and a conditional false accept probability was 1 in 1031. No false accepts or false rejects were experienced in the first test21. In the second study up to 122 people were compared to a database of 403. There were some false rejects in this test but most people were accepted on retries and the remaining were explained to be errors in use such as position or in eyeglass difficulties due to glare. This test showed no false accepts. These 19 Ibid. 1358-1359. 20 Ibid 1361-1362. 21 Ibid 1361-1362 two tests, while valid, need to be accepted with care because of the small sample size22. More test of the Daugman systems have probably occurred but results could not be found. The Wildes system takes 10 seconds for both enrollment and verification and does not have an identification mode. The only test that this system had was of 60 irises from 40 different people. Twins were included in this test population. There were no false positives or false negatives in this test. Like the other tests, this test did not have a large enough sample population to be considered conclusive. Even though the tests of both the Daugman and Wildes systems did not have ideal sample populations, the results do present a positive outlook for iris recognition technology23. Possible Improvements Even though current methods of iris recognition technology are sufficient for today’s needs, improvements to the technology could always be made. One of the first improvements would be the use of color cameras for image acquisition. The use of color would create an additional level of security. Not only would the patterns of the irises have to match (as is currently tested), but the color would also have to match. Color would also give an additional way to index images for better searching through databases24. With color indexing, only 22 Ibid 1361-1362 23 Ibid 1361-1362 24 Wildes, 1353. images that have similar coloration would be considered for comparing instead of the whole database. Another improvement would in the area of iris acquisition. Even though iris recognition technology is mostly non-invasive, it still requires a certain amount of user cooperation in order to be successful. A person has to walk up to an iris recognition unit and intentionally position themselves to be read. An improvement would be a system in which an iris recognition unit could record an image of an iris with little user input. This could be done by taking a picture from a meter or more away rather than the 15-50cm that is currently required. It would also require the camera to distinguish between the face and the rest of the body. Once recognized, the camera could zoom into the face and take a picture containing the iris. This improved acquisition would allow for much more relaxed iris recognition and could result in a more widespread application of the technology25. Current Applications There are many current applications of iris recognition technologies. The predominate use of iris recognition technology today is at airports. The technology was first tested in July 2000 at Charlotte/Douglas International Airport in North Carolina and by EyeTicket Corporation26. Since then many more airports have tested or embraced iris recognition technology as a means of 25 Wildes, 1353 26 Mehan, Michael. “Iris Scans take off at airports.” 17 July 2000. 18 February 2005 <http://www.computerworld.com/securitytopics/security/story/0,10801,47202,00.html>. identification. Amsterdam Airport Schiphol began using the technology in conjunction with a smart card in October 200127. The United States Homeland Security Chief Tom Ridge recently announced that iris recognition technology will be used at New York’s John F. Kennedy Airport as result of the success in Amsterdam. The technology will be used at the JFK airport to speed up the customs process for frequent travelers28. Other current applications of iris recognition technology include correctional facility identification A.T.M., verification, pharmaceutical dispensing, and border control. One of the first uses of the technology was in 1996 when Lancaster County Prison in Pennsylvania used it to verify the identity of prisoners to be released. In 1998 Nationwide Building Society bank in England started using iris recognition instead of PIN numbers for their A.T.M.s29. Argus Solutions of Australia created a system which uses iris recognition to dispense drugs to verified patients30. More recently, the governments of Singapore and the United Arab Emirates have used iris scan technology for board control. The technology is used in Singapore at its border with Malaysia31. The United Arab Emirates uses it to check if a person entering the country is one of the 544,000 people that were expelled from the nation32. As iris recognition technology is applied to an 27 Henahan, Sean. “The Eyes Have It.” 17 June 2002. 18 February 2005 <http://www.accessexcellence.org/WN/SU/irisscan.html>. 28 Bishop, Ian. “Eye Flight: Iris Scan for JFK Passengers.” 14 January 2005. 18 February 2005 <http://www.nypost.com/news/regionalnews/38159.htm>. 29 Henahan 30 Argus Solutions. “Dispense True Identity.” 18 February 2005 <http://www.argus- solutions.com/true_dispense.htm#>. 31 Iternational Biometric Group. “Typical Iris Recognition Applications.” 18 February 2005 <http://www.biometricgroup.com/reports/public/reports/iris-scan_applications.html>. 32 Daugman, John. “Largest Current Deployment of Iris Recognition.” 18 febr 2005 <http://www.cl.cam.ac.uk/users/jgd1000/deployments.html>. increasing number of situations and as the technology gets better more people will embrace its methods. Companies There are many companies that are involved with iris recognition technology. LG Electronics is one of the largest manufacturers of iris recognition technology with over 1000 systems in six continents33. Their system is called IrisAccess 3000 and involves three main components. Two separate iris readers are used, one for enrollment into the database and one for iris image acquisition. A control unit is used in conjunction with the acquisition unit to verify a person’s identity and then perform the desired operation upon verification. LG’s system provides both audio and visual cues to help a person use the system. An additional feature of their system is that the iris images are stored on the control unit and not the iris readers. IrisGuard Incorporated focuses on large scale uses of iris recognition such as border crossings, airport security, and law enforcement. Their technology, called Iris Farm Architecture (IFA), allows for the splitting of one Iris database between an unlimited number of database storage units. It also supports slow speed communications between databases and image acquisition units, allowing recognition to occur even when communications are slow. Not only does it allow for slow connection, but is also has become, “the fastest and most scalable server architecture that exists today for large-scale IrisCode database 33 LG Electronics. “Overview.” 18 February 2005 <http://www.lgiris.com/products/index.html>. searches34.” One aspect that distinguishes IrisGuard’s product, the H100, from others is the variety of configurations in which it can be used. It can be placed on a tripod, attached to a swinging metallic arm, or even operated by hand, in addition to being used in the standard wall mounted position. Oki Electric Industries produces two models for iris recognition. The IRISPASS-H is a small hand-held device that is used with a personal computer to identify a user. Oki’s more comprehensive unit is the IRISPASS-WG. It is wall mounted and can be used in conjunction with 126 other units to maintain security at a site. The IRISPASS-WG includes a feature that automatically detects the location of the iris, meaning that users only have to stand in front of the unit to get identified and not peer into a small recognition unit35. EyeTicket Corporation focuses on travel processing and access control using iris recognition. Its two lines of products are EyePass and JetStream. The EyePass line has a standard iris recognition unit called EP-1 but also has two more complex units, the EP-2 and EP-3. The EP-2 provides “piggyback” prevention, meaning that no one else can get through the access point other than the verified scanned user. This is achieved with a two door system and a pressure sensitive floor in between. The unit identifies the user, opens the first door, and allows the user to walk into the middle chamber. This chamber then uses a pressure sensitive floor to verify that only one person has walked through. Once this condition is met, the second door is opened and the user is allowed to 34 Daugman, Deployments. 35 Oki Electric Industries. “Oki Introduces the IRISPASS®-WG Iris Recognition System with Automatic Iris Scanning Function.” 12 June 2002. 18 February 2005 <http://www.oki.com/en/press/2002/z02011e.html>. pass. EyeTicket’s second line of products is JetStream. Jetstream is a system in which users can be positively identified and quickly processed for applications such as airline, hotel, rail, passport and visa36. Iridian Technologies is the leading producer of iris recognition technology. They research and develop iris recognition technology and hold U.S. and international patents on the fundamental concepts and technologies behind iris recognition37. Iridian’s technology is realized in two ways. The first is by their PrivateID software that is used in iris recognition cameras made by companies such as Oki and Panasonic. The second way that Iridian’s techonology is used is through their Proof Positive product certification. This certification assures that iris recognition products meet specified standards. Additional companies that deal with iris recognition technology include Panasonic, IBM, and SecuriMetrics. Panasonic has multiple iris recognition products that are used in a number of applications. IBM supplies databases and servers for iris recognition. SecuriMetrics produces Portable Iris Enrollment and Recognition (PIER) devices. These units are primarily used for military and law enforcement and have been used in Iraq and worldwide. 36 EyeTicket Corporation. “Index.” 18 February 2005 <http://www.eyeticket.com/index.html>. 37 iridian technologies. “About Iridian.” 18 February 2005 <http://www.iridiantech.com/about.php>. Conclusion The demand for security technology increases as the world becomes more dangerous. Many emerging technologies such as facial recognition and vocal patterns have tried to gain a share of the industry. However, iris recognition technology has stood at the forefront. The benefits of the technology include speed, reliability, and ease of use. Its implementation in diverse settings has proved it to be a successful method of identification. No other technology can offer the features and benefits of iris recognition. Expansion and continued development of iris recognition technologies provides a promising look at a safer and more secure future.
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