11General interestRetinal recognitionBiometric technology in practice by Ravi DasWhile considered invasive and expensive,retinal recognition is still the mostreliable and stable means of biometricidentification. Although the advantages ofretinal recognition currently outweigh thedisadvantages, its widespread use is heldback by public acceptance. As Ravi Dasexplains, there is every reason to believethat this may well change.This article focuses on a unique biometric technology: in the front of the eye, while the retina is located at Ravi Das is a Consultantretinal recognition. Unlike other biometric technologies, the back. Because of its position within the eye, the for HTG Solutions. Heincluding fingerprint recognition, facial recognition, retina is not exposed to the external environment. As a has been involved iniris recognition, hand geometry recognition, voice biometric, it is therefore very stable. the IT industry for 10recognition, keystroke recognition, and signature years and launchedrecognition, retinal recognition is not widely deployed Figure 2 shows a front view of the blood vessel pattern HTG’s security solutionsin commercial applications. within the retina. The red lines represent the actual division in January blood vessels; the yellow section indicates the position 2003. This divisionThe anatomy and the uniqueness of the of the optic disc (the place where the optic nerve offers a completeretina joins the retina). It is from here that information is security solutions transmitted to and received from the brain. The circle in package and usesWhen talking about the eye, especially in relation to the diagram indicates the area that is typically captured biometric technologybiometrics, the iris and the retina are often confused. by a retinal scanning device. It contains a unique as its main productWhile they may both be categorised as ‘eye biometrics’, pattern of blood vessels. offering. Ravi holdstheir respective functions are completely different. The a Master of Scienceiris is the coloured region between the pupil and the There are two famous studies that have confirmed the Degree in Agribusinesswhite of the eye (also known as the sclera). The primary uniqueness of the blood vessel pattern found in the Economics frompurpose of the iris is to dilate and constrict the size of retina. The first was published by Dr Carleton Simon Southern Illinoisthe pupil. In this sense, the iris is analogous with the and Dr Isodore Goldstein in 1935, and describes how University and aaperture of a camera. every retina contains a unique blood vessel pattern. Master of Business In a later paper, they even suggest using photographs AdministrationIt is said that the retina “is to the eye as film is to a of these patterns as a means of identification. The (specialising incamera.”1 The retina consists of multiple layers of second study was conducted in the 1950s by Dr Paul Managementsensory tissue and millions of photoreceptors whose Tower. He discovered that - even among identical twins Information Systems)function is to transform light rays into electrical - the blood vessel patterns of the retina are unique and from Bowling Greenimpulses. These impulses subsequently travel to the different. State University.brain via the optic nerve, where they are convertedto images. Two distinct types of photoreceptors exist The technology behind retinal recognitionwithin the retina: the rods and the cones. While thecones (of which each eye contains approximately The first company to become involved in the6 million) help us to see different colours, the rods research, development and manufacture of retinal(which number 125 million per eye) facilitate night and scanning devices was EyeDentify Inc. The companyperipheral vision. It is the blood vessel pattern in the was established in 1976 and its first retina capturingretina that forms the foundation for retinal recognition devices were known as ‘fundus cameras’. Whileas a science and technology. intended for use by opthamologists, modified versions of the camera were used to obtain retina images. TheFigure 1 shows a side view of the eye - the iris is located device had several shortcomings, however. First, the Keesing Journal of Documents & Identity, issue 22, 2007 12 General interest Figure 1 Side view of the eye.equipment was considered very expensive and difficult company is working on a prototype device that will beto operate. Second, the light used to illuminate the much easier to implement in commercial applications.retina was considered too bright and too discomforting It will also be much more user friendly. Based onfor the user. a scientific study whitepaper written by Retinal Technologies, it appears that the methods used forFurther research and development yielded the first true testing their device reveal “huge potential.”2prototype scanning device, which was unveiled in 1981.The device used infrared light to illuminate the blood The overall retinal scanning process may be brokenvessel pattern of the retina. The advantage of infrared down into three sub-processes3:light is that the blood vessel pattern in the retina can‘absorb’ such light much faster than other parts of the 1. Image/signal acquisition and processing ‑ this sub-eye tissue. The reflected light is subsequently captured process involves capturing an image of the retina andby the scanning device for processing. In addition to converting it to a digital format.a scanner, several algorithms were developed for theextraction of unique features. Further research and 2. M atching: a computer system is used to verifydevelopment gave birth to the first true retinal scanning and identify the user (as is the case with thedevice to reach the market: the EyeDentification other biometric technologies reviewed in previousSystem 7.5. The device utilised a complex system of articles).scanning optics, mirrors, and targeting systems tocapture the blood vessel pattern of the retina. Ongoing 3. Representation: the unique features of the retina aredevelopment resulted in devices with much simpler presented as a template.designs. Later scanners consisted of integrated retinalscanning optics, which sharply reduced manufacturing The process for enrolling and verifying/identifying acosts (compared to the EyeDentification System 7.5.). retinal scan is the same as the process applied to other biometric technologies (acquisition and processing ofThe last retinal scanner to be manufactured by images; unique feature extraction; template creation).EyeDentify was the ICAM 2001, a device capable of The image acquisition and processing phase is thestoring up to 3,000 templates and 3,300 transactions. most complicated. The speed and easy with which thisThe product was eventually withdrawn from the market sub-process may be completed largely depends on useron account of its price as well as user concerns. As cooperation. To obtain a scan, the user must positionfar as the author is aware, only a single company is his/her eye very close to the lens. To safeguard thecurrently in the process of creating a retinal scanning quality of the captured image, the user must alsodevice: Retinal Technologies, LLC. It is believed that the remain perfectly still at this point. Moreover, glasses must be removed to avoid signal interference (after all, lenses are designed to reflect). On looking into theKeesing Journal of Documents & Identity, issue 22, 2007 13General interest scanner, the user sees a green light against a white 1. L ack of cooperation on the part of the user - as background. Once the scanner is activated, the green indicated, the user must remain very still throughout light moves in a complete circle (360 degrees). The the entire process, especially when the image is blood vessel pattern of the retina is captured during being acquired. Any movement can seriously affect this process. Generally speaking, three to five images lens alignment. are captured at this stage. Depending on the level of user cooperation, the capturing phase can take as long 2. T he distance between the eye and the lens is as one minute. This is a very long time compared to incorrect and/or fluctuates - for a high quality scan other biometric techniques. to be captured, the user must place his or her eye in very close proximity to the lens. In this sense, iris The next stage involves data extraction. One very scanning technology is much more user friendly; a considerable advantage of retinal recognition becomes quality scan can be captured at a distance of up to evident at this stage. As genetic factors do not dictate three feet from the lens. the pattern of the blood vessels, the retina contains a diversity of unique features. This allows up to 400 3. A dirty lens on the retinal scanning device. This will unique data points to be obtained from the retina. For obviously interfere with the scanning process. other biometrics, such as fingerprints, only 30-40 data points (the minutiae) are available. 4. Other types of light interference from an external source. During the third and final stage of the process, the unique retina pattern is converted to an enrolment 5. T he size of the user’s pupil. A small pupil reduces the template. At only 96 bytes, the retina template is amount of light that travels to (and from) the retina. considered one of the smallest biometric templates. This problem is exacerbated if the pupil constricts as a result of bright lighting conditions, which can result Causes of problems (errors) and biometric in a higher False Reject rate. performance standards All biometric technologies are rated against a set of As is the case with other biometric technologies, the performance standards. As far as retinal recognition is performance of the retinal scanning device may be concerned, there are two performance standards: the affected by a number of variables, which could prevent False Reject Rate, and the Ability To Verify Rate. Both an accurate scan from being captured. Poor quality are described below. scans may be attributable to: False Reject Rate (also known as Type 1 Errors) Describes the probability of a legitimate user being denied authorisation by the retinal scanning system.Figure 2Front view of the bloodvessel pattern within theretina. Keesing Journal of Documents & Identity, issue 22, 2007 14 General interestRetinal recognition is most affected by the False Reject geometry recognition, facial recognition, and, to someRate. This is because the factors described above have extent, iris recognition).a tangible impact on the quality of the retinal scan,causing a legitimate user to be rejected. To date, retinal recognition has primarily been used in combination with access control systems at highAbility to Verify Rate security facilities. This includes military installations,Describes the probability of an entire user group being nuclear facilities, and laboratories. One of the best-verified on a given day. For retinal recognition, the documented applications involves the State of Illinois,relevant percentage has been as low as 85%. This is which used retinal recognition to reduce welfare fraudprimarily attributable to user-related concerns and the by identifying welfare recipients (thus preventingneed to place one’s eye in very close proximity to the multiple benefit payments). This project also madescanner lens. use of fingerprint recognition. Retinal recognition was first introduced in Granite City and East AltonThe strengths and weaknesses of retinal recognition (southern Illinois) towards mid-1996. Once theJust like all other biometric technologies, retinal fingerprint recognition programme had been initiated,recognition has its own unique strengths and the authorities drew up a comparison betweenweaknesses. The strengths may be summed up as fingerprint and retinal recognition, concluding thatfollows: “retinal scanning is not client or staff friendly and requires considerable time to secure biometric records.1. T he blood vessel pattern of the retina rarely changes Based on these factors, retinal scanning technology is during a person’s life (unless he or she is afflicted by not yet ready for state-wide adaptation to the Illinois an eye disease such as glaucoma, cataracts, etc). welfare department…”4. As a result, the use of retinal recognition systems was stopped.2. T he size of the actual template is only 96 bytes, which is very small by any standards. In turn, To conclude verification and identification processing times are much shorter than they are for larger files. In view of the rich and unique blood vessel patterns in the retina, there is no doubt that retinal recognition is3. The rich, unique structure of the blood vessel pattern the ‘ultimate’ biometric. Its high cost and user-related of the retina allows up to 400 data points to be drawbacks have prevented it from making a commercial created. impact. However, as technology continues to advance, it seems likely that retinal recognition will one day be4. As the retina is located inside the eye, it is widely accepted and used. not exposed to (threats posed by) the external environment. For other biometrics, such as 1 “Retina Identification”, Robert “Buzz” Hill. Article is from fingerprints, hand geometry, etc., the opposite holds the book: “Biometrics: Personal Identification in Networked true. Society”, by Anil Jain, Ruud Bolle, and Sharath Pankati ‑ p.124 2 “Retinal Identification System: Performance Analysis”The most relevant weaknesses of retinal recognition Scientific whitepaper provided by Retinal Technologies, LLCare: 3 “Retina Identification”, Robert “Buzz” Hill. Article is from the book: “Biometrics: Personal Identification in Networked1. T he public perceives retinal scanning to be a health Society”, by Anil Jain, Ruud Bolle, and Sharath Pankati - p.126. threat; some people believe that a retinal scan 4 www.dss.state.ct.us/digital/illinois.htm damages the eye.2. U ser unease about the need to position the eye in such close proximity of the scanner lens.3. User motivation: of all biometric technologies, successful retinal scanning demands the highest level of user motivation and patience.4. R etinal scanning technology cannot accommodate people wearing glasses (which must be removed prior to scanning).5. A t this stage, retinal scanning devices are very expensive to procure and implement.Retinal recognition applicationsAs retinal recognition systems are user invasive as wellas expensive to install and maintain, retinal recognitionhas not been as widely deployed as other biometrictechnologies (particularly fingerprint recognition, handKeesing Journal of Documents & Identity, issue 22, 2007
General interest Retinal recognition - Biometric News
Description: Keesing Journal of Documents & Identity, issue 22, 2007 This article focuses on a unique biometric technology: retinal recognition. Unlike other biometric technologies,