An introduction to Vein Pattern Recognition Technology

Vein Pattern Recognition (VPR) is an automated, physical biometric that identifies us by the unique pattern of veins in our palms or fingertips. Today, as people around the world prioritize hygiene to prevent the spread of COVID-19, many organizations have begun adopting VPR technology because it requires no direct, physical contact to make an accurate identification. 

Thanks to a helpful feature of the proteins in our blood, VPR scanners can accurately detect vein patterns with the user’s hand hovered over or within a sensor. The scanners work by illuminating the hemoglobin (a protein that carries oxygen through the bloodstream) in our veins with NIR (near-infrared) light. The scanners create an image of the vein pattern by capturing either the reflected light or the light that passes through the target.

Why use Veins for Recognition

Just like our eyes and fingerprints, our vein patterns develop before birth and retain unique features with which biometric tools can distinguish us from others.

Some may wonder why we scan for veins instead of arteries. We use veins because they have the following features that allow us to scan them more easily than arteries: 

• Veins are much larger than arteries.
• Veins lie closer to the surface of the skin.
• The veins absorb much more NIR light than arteries and, thus, appear much darker and more defined when scanned.  

An example of a vein pattern captured with NIR light can be seen below:

Source

The Components Of Vein Pattern Recognition

A VPR system consists of four major components:

1. A sensor with NIR LED lights to illuminate the hemoglobin in our veins.

2. A high-resolution Charged Couple Device (CCD) camera.

3. A processing unit to extract the unique pattern of blood vessels from captured images and produce templates containing an individual’s identifiable features for enrollment and verification.

4. A database to store the enrollment and verification templates, as well as a log of all transactions.

How Vein Pattern Recognition Works

To use a VPR system, the user only needs to place their palm or fingertips into a scanner. Some scanners have guides to help the user properly position their hand. Although, the guides require direct physical contact. Without guides, the sensor remains completely contactless.

After the user properly positions their palm or fingertip, the system illuminates the unique pattern of blood vessels by one of two techniques:

Diffused Illumination

Located on the same side of the VPR system as the NIR light source, the VPR sensor captures the NIR light reflected from the palm or the fingertips.  With diffused illumination, the thickness of the skin does not affect the raw image of the veins.

Direct Illumination 

Direct illumination involves flashing NIR light directly through the palm or fingertips and capturing the light from the opposite side of the target. The thickness of the skin may affect the light’s ability to shine through the target onto the sensor.  The system can flash the NIR light from above, below, or the opposite sides of the VPR scanner. Each scanner position has its own advantages and disadvantages:

• Top lighting results in the clearest raw image of the vein patterns, but these lighting units can be large and collect dust quickly.

• Side lighting requires more NIR lighting power than other methods, as well as more processing power to capture the raw image of the vein pattern.

• Bottom lighting—the cheapest option—is much more sensitive to NIR light, and this sensitivity may cause inaccuracies in identification.

Once the system captures raw images of the veins, specialized software normalizes the raw images and removes any obstructions, such as hair on the surface of the skin.  

The extraction algorithms then determine the unique features of the vein pattern and create the enrollment template, storing it in a database to compare with the verification templates of future transactions.

The graphic below illustrates an example of a VPR system:

Source

Vein Pattern Recognition Advantages & Disadvantages

We can evaluate VPR’s advantages and disadvantages compared to other biometrics using the following criteria:

1. Uniqueness:  

Vein patterns are truly unique. Scientific studies have shown that every individual has a one-of-a-kind vein structure; even identical twins have different vein patterns.

2. Universality:  

Because VPR can identify people using a few different body parts, such as the palms, fingertips, or a combination of both, the technology is very versatile and accessible to nearly everyone.

3. Permanence:  

Researchers remain unsure whether our vein patterns change over our lifetimes. If vein patterns do change, VPR systems may need to re-enroll people periodically to avoid identification errors.

4. Collectability:  

Organizations can use, manage, and deploy VPR technology with ease. Collecting verification templates takes less than a second, and, since this is a contactless technology, dirt, cuts, bruises, and moisture on the skin’s surface do not affect raw image collection.  The thickness of the skin remains the only variable that can affect the quality of raw images.

5. Performance:  

VPR possesses two distinct advantages in performance compared to traditional biometric technologies.

1. VPR matching algorithms are simple and require less processing power and storage space.

2. Due to great advancements in sensor technology, VPR systems have decreased in size and become better suited for small-scale applications like smartphone security.

However, VPR performance suffers the disadvantage of being susceptible to ambient light interference during raw image collection.

6. Acceptability:  

Because VPR technology requires no direct contact, many organizations value it as a hygienic method of user authentication. VPR also does not evoke any privacy rights issues because, unlike our faces and voices, an individual’s vascular pattern remains invisible to the outside world.

7. Resistance to circumvention:  

VPR systems prove incredibly difficult to spoof because capturing images of the veins requires active blood flow in the palm or fingertips used for recognition.

Conclusion

Vein pattern recognition technology satisfies many organizations’ need for an accurate, hygienic, and universal biometric tool to use for rapid authentication. Consisting of only four components—a camera, an NIR light, a processor, and a database—VPR systems accurately identify us with our one-of-a-kind vein patterns and, therefore, prove extremely resistant to circumvention.

Due to VPR’s versatility and because of current COVID-19 hygiene protocols, vein pattern recognition systems remain excellent tools for organizations hoping to efficiently and safely identify clients and employees.