Windows Hello – What's the difference between an iris scanner and 3D facial recognition?

After posting our report earlier on Microsoft's October plans a bit of confusion cropped up in comments. Why would I worry that a Windows Hello camera cannot fit into a 12-inch Surface, but it can in a phone?

The answer is simple but requires a bit of explanation. The shorter answer is there are two different technologies for Windows Hello (three, when you add in fingerprints).

Facial Recognition

Facial recognition right now is being accomplished with the Intel RealSense F200 reference camera reference design. Some laptops are already using it (see here), and more will be in the coming year. That is the camera we have demonstrated on video as a development device that you can order from Intel.

The F200 is not tiny (Note: the F200 is front-facing; R200 is world-facing). For instance, it has three cameras, not just one. Those cameras are:

  1. Infrared
  2. 3D
  3. Traditional RGB (aka webcam)

Moreover, the F200 is more than just facial analysis as it can also be used for hand/finger tracking, speech recognition, augmented reality, and background segmentation.

The F200 is more like a full-blown Kinect camera. It also happens to be Windows Hello ready so that you can use your face to unlock your computer. It is chunky too, which is why it is harder to jam into a small bezel display.

3D facial recognition is good because it works at a distance (0.2 – 1.2-meter range). That makes it ideal for PCs and laptops since the user is pushed back further from the display.

Iris scanner

When it comes to the eyes, there are two methods: iris and retina scanning. Retina scanner scans the blood vessel patterns at the back of the eye and is a very reliable and foolproof system. Iris scanning just scans the patterns on the colored part of the eye in front. Iris scanning can be done with a camera. Retina scanning, well, is more complicated.

Iris scanning is what we are talking about when it comes to Windows Phone. You only need existing camera technology to make it work. There should be no "extra" hardware, unlike 3D facial recognition. Besides the camera, you usually need a light-emitting diode and a light-receiving sensor. These light up the eye usually with an invisible light (near-IR) so that the camera can scan the iris. The scanner works in low light (even dark rooms) and works with clear contact lenses, eyeglasses, and non-mirrored sunglasses.

Iris scanners are much cheaper to implement than fingerprint scanners (extra hardware) and much smaller than 3D facial recognition (two fewer cameras).

Iris scanners need to be much closer to the face to pick up the details of the iris (think arm's length, maybe a bit less). Because of its smaller size, cheaper components and ability to work close to the face, it is ideal for phones. This is why the Lumia 950 and Lumia 950 XL are going to feature this type of technology.

Sure, a 3D facial recognition camera system would be great for phones too, but the price and size of the hardware is just too massive for a mobile. Maybe someday.


When it comes to Windows Hello, Microsoft, and their partners have three options:

  • 3D Facial Recognition
  • Iris Scanning
  • Fingerprint Scanning

It is also very likely that any biometric system can hook into the Windows Hello system as the technology comes online. Each one has advantages and disadvantages, including range, accuracy, costs, and size. One downside of fingerprint scanning is you cannot wear gloves with it, so it's bad in the winter, and you need your finger ideally placed. Fingerprints can also be lifted since we leave prints all around although "fooling" a scanner with them is not so easy either.

When it comes to Windows Hello, expect the larger, more robust facial recognition for PCs and the smaller, more cost efficient iris scanner for phones. Got it? Great, now go forth and spread the word!

Daniel Rubino

Daniel Rubino is the Editor-in-chief of Windows Central, head reviewer, podcast co-host, and analyst. He has been covering Microsoft since 2007 when this site was called WMExperts (and later Windows Phone Central). His interests include Windows, laptops, next-gen computing, and for some reason, watches. Before all this tech stuff, he worked on a Ph.D. in linguistics, watched people sleep (for medical purposes!), and ran the projectors at movie theaters because it was fun.

  • Great summary Daniel! Thanks
  • I still expect someone to say this -
    " Iris scanner wont be supported in my Lumia 520 when i upgrade to W10M ?.. Now there is not even one good reason to stay in WP.. I'm going to buy an iPhone instead...bye MS.." /s*5 :D
  • Very informative article, Daniel.
  • So true.
  • You complain about the cheapest possible Win phone and say you are going to an expensive iphone.  Make some sense.  If you were complaining about a 1520 maybe then you would have a point.
  • Calfee20, I guess you haven't read some of the ignorant comts posted on WC by some users. The sad part is, iJUNK cost only $75 to $110 to make depending on its storage, However, since CrApple adds a HUGE price tag on it, just to make people think its so........(but still is a cheap crap phn), people think they are getting something so special. in any case, people just want the world from MS, even if its $30 item, but NOTHING whatsoever from CrApple with their overrated trash that is 4 years behind technology of others. You NEVER see or hear an iSHEEP, BoooHoooing and saying"""I paid a ridiculous price of $1000+ for this iJUNK phn and I want it to have 1080p screen, 20 Pix cam, MicroSD slot, much higher capacity battery........................"""". Now on other hand, some of WP users say""""I paid $30 for this phn and it does not wipe my butt, it does not make me a sandwich, it does not chew it for me, it does not wash my car,...........I am sick of it, I'm switching to iJUNK, I'm done"""""
  • I hope you're not serious because, well, read the comment.
  • So I can still brag about next level tech in my phone when it's just a camera and TV remote (essentially) :P
  • Just like, by the same level of abstraction, your computer is just a calculator.
  • When you show people how it works, just explain it to them with big words. Infrared Wave Refraction. Something like that. They'll think it's awesome. Also, I guess it's time to replace all my sunglasses with non-mirrored versions.
  • Great article. And fast. Can't let bad info spread... Remember the active listening "Hey Cortana" debacle? Lol
  • Good to know that it works with contacts. I was worried about that.
  • And glasses! If users had to remove their glasses each time, it wouldn't be functional at all.
  • Can't speak for the Iris scanners that they will have in mobile devices but the 6 year old Iris Scanners I've used in the past worked when I as wearing glasses and even sunglasses.
  • Article says it works with glasses
  • And how do these scanners compare when it comes to security? How easy can the iris scanner be fooled (e.g. with a photo??
  • It's very good as you would ideally need a very high-resolution image of someone's eye to fool it. I think it can be fooled in the right circumstance, but these are rather rare. We'll have to wait until MS details how their tech works, howeve.
  • Haha... Imagine the irony if the only phone camera capable of producing images detailed enough to fool this system was the 1020. Lol. :)
  • Iris scanners are very accurate and very hard to fool. Your eyes are as unique as a finger print. I've visited many secure datacenters in the past that used Iris Scanners to grant access. It's just a question of how will it would work in a mobile devices. If it works with normal use then it will be amazing, if you have to move your eye in position then it becomes more of a gimmic than practical for regular consumer use. The concern is the Iris scanners I've used (albiet older technology) required me to be at a specific range from the device for it to work.
  • Paranoia from both sides of the coin
  • Awesone now i understand thanks Daniel
  • If I have to hold the phone 5cm from my eye, the fun is gone.
  • It's not like that. It's a camera, not a macro lens. I think a retina scanner needs to be very close since it is scanning the back of the eye.
  • The Iris scanner has to focus on the back of your eyeball.  So the camera needs to look through the lens of your eye and manage this focal length.  This is much more difficult than taking a picture of your eye.  Remember that many cameras have the "red eye" filter.  The "red eye" is caused by the camera flash reflecting off your retina and returning to the camera.  The camera software probably looks for an aspect in the exposure (a certain wave length in a small defined location) and turns it black.  Clearly, developing the software to isolate the eye and then the iris on a person face is fairly simple.  The only question left is can the camera see your eye?  Once it sees your face and isolates your eye, then it is simply compares the pattern to a pattern in memory.  What I don't know is if the system converts the iris to a grey scale image to match the iris in memory.  I would think it does because the color variation is not as critical as the variation in wavelength.  For instance, in bright light, my eyes appear more green.  However, in low light, my eyes appear brown.  If you convert the iris to a grey scale image then the variation in wavelength is not impacted by the ambient light conditions.
  • The only thing I'm worried about with regards to the Iris Scanner in 950 and 950XL is if you have to hold the phone all the way up to your eye for it to scan. If this is required, it completely destroys the chances of people actually using it and demotes it to a gimmick feature, albiet one that probably works really well. Remember, the Touch ID system on the iPhone 5S and higher gained popularity because there was literally no effort required to use it, but was more secure then a PIN code. Same thing with desktop Windows Hello face recognition, All you have to do is look at it, and it unlocks your PC/Tablet. It requires no effort whatsoever. If the Iris Scanner actually does require you to hold the phone up to your face, not only does it look weird, but it also requires effort, so not many people will use it. I'd rather they have used a Fingerprint Sensor instead.
  • Focal points on FF cameras are not very good. We are not talking about macro imaging, just a regular camera photo e.g. selfie style, holding the camera in front of you.
  • Well in that case, I guess it should be fine then lol
  • Yeah, I think the confusion is with a retina scanner, which I believe does need to be much closer to read the blood vessels at the back of the eye. More accurate, more secure, less convenient.
  • Dan, First- big fan. Second, I find​ it funny there was any speculation regarding putting realsense into an sp4, but there's NO speculation of using an Iris Scanner there? Forgive me if other commenters have already mentioned it, but certainly the expected use case of an sp4 would put it an an adequete distance for using an sp4. Lastly- when can I buy a realsense camera for my desktop?? I still run an i7 920- which doesn't fit the hardware reqrements of the F200, but I have a hard time believing my CPU couldn't handle it. There still aren't any cortana/hello enaled consumer webcams on the market. What gives? I've got a tricked out custom gaming rig. My webcam "works" with cortana, but hey cortana is spotty at best. You're my trusted source, buddy.      
  •   The 3D real sense camera has much more real world use cases other than facial recognition.  For instance, a R200 can scan a box and accurately detemine its dimensions.  Intel demostrated a tablet that look at several boxes, determined each box's dimensions.  Then the user entered the number of each box.  the software then showed the user how to stck the boxes to take up the least amount of room.  Think of a warehouse situation.  But you can apply this to many other things. If the iris scanner is good enough for Hello, then the R200 would be best for the SP4.
  • Touch ID is a bit gimmicky. I know a few people that have iPhones that don't use it because it doesn't always work. We will see how the iris scanning compares.
  • I dont think so.. Almost everyone i know uses the touch ID on their iPhones..some may disagree.. But Its not a gimmicky anyways.. It has its own cons..
  • Samsung and Apple both have good FP systems; I use both and like them a lot. Way easier than a PIN. TBH, I kind of wish MS would use FP as it is more well known; we'll have to wait and see how the sell iris scanning, however.
  • Rather than calling it just an Iris scanning feature.. MS should name it in a fancy way.. Like apple do with their 'iSight' camera.. And their force touch.. Oopppzz.. "3d touch" ... You know what I mean ;)
  • Windows Hello isn't flashy?
  • It's just a gimmick any way you look at it. It is currently too slow to be practical. You are much faster swiping up the keypad and typing pin than waiting for iris scanner to catch up, especially in bad lighting conditions/ with glasses on. It's like Hey Cortana. It's nice but I found myself not using it just because it is so unreliable. And it usually does not work at all at the moment you want to demo it to someone else... Go figure
  • Great report Daniel, thanks! Also, is it weird I heard your voice in my head when I read the article?
  • You should consult a doctor :p
  • "You only need existing camera technology to make it work.​" Hm, Can I use a existing camera for Iris Scanner on my PC?
  • Read further.. He talks about a LED and LRS ... So nope... You cant use an existing camera for Iris scanner on any device without a LED and LRS on it..
  • Sounds easily to copy. Nice blown up picture of an eye. Pin it is for me for security.
  • You just pick up the Lumia 950 (XL) phone and it'll scan your iris and unlocks the phone. It's THAT simple! :-)
  • I hope it is..
  • Although iris is cool, it still would've been nice for a fingerprint scanner to be incorporated into the power button on the side of the upcoming flagships. Maybe we'll be surprised, but it's highly doubtful.
  • Not likely..
  • Yes, it is doubtful. Maybe a third party OEM will make this a reality for us. If not, perhaps the metal Microsoft-designed phone will include something along these lines.
  • Great article. Well explained, thanks a lot.
  • Great article, as always, WC is the best for Microsoft news.
  • Hmm, I wonder how well that iris scanner is going to work with the gas permeable lens on my eyeball.
  • nice article, hope to see a cheaper 3D facial recognition camera... 99$ is a bit expensive juste to use the hello fonction...
  • This is great tech BUT .... the only concern with any biometric information used as log ins, is how is the information stored on the PC, how is it encrypted and how it is protected against theft or other misuse if your PC is stolen or compromised, for example. Because its one thing to have your password stolen, you just replace it with a different one, but its not like you can replace your face, eyes, or fingers, if someone steals the information that these cameras and sensors read and store about you for match comparison when loging in.  
  • Are you kidding? You're just supposed to trust Microsoft that they have encrypted it properly and that no one will ever be able to 1) access it and 2) find a way to use the underlying graphical data to circumvent other biometric systems in the future by feeding your old biometric data directly into those systems! /s But in seriousness, this is the largest risk to using these things - at the end of the day, no matter how complex the algorithims are for doing the compares, they are comparing data vs data and, as you say, a password is not eternal. Nor is stored data completely safe. I think the hope has to be that any future login for anything important (banks, work, healthcare, etc) will require biometric plus password to have the best of both worlds (because, frankly, there are probably loads of pictures with names on Facebook that would allow for a decent enough iris graph). I suspect the belief with W10 is that at this stage in the biometric game, it's just not important enough to have multiple credentials and it would certainly hinder the 'wow' factor of people being able to unlock their device with their face or eye or finger. Right now, Microsoft needs all the 'wow' it can get. 
  • I think the fingerprint is definitely a bigger security risk. I highly doubt the average person is posting pictures of their eyes which are detailed enough to be use to fool a scanner, and additionally, you'd have to find a way to reproduce a picture that reacts to infrared realistically. As far as data safety goes, all this stuff is stored locally and protected on the machine. If you lose your device, lock or reset it. If you lose your device, or someone gains access to your browser data, you're at much higher risk of someone grabbing CC or SSN numbers.
  • I think you missed the point of these two comments, which was a discussion that goes beyond W10's specific use of biometrics for a computer or phone. It was that future biometric use outside of your personal device should not just use biometrics-only but a mix of bio and variable credentials since biometrics can be collected but cannot (easily) be changed as passwords can. It's not necessary for someone to post pictures of their eyes specifically if the resolution is good enough for software to focus in on the patter of the iris - which, needless to say, would be an awful biometric for anything important like a bank for that specfic reason. And of course, keep in mind this isn't refering to someone trying to fool a scanner (someone holding a picture of a big roomy eye in front of someone's phone), but about feeding the underlying biometric map to the backend to gain access (again, not talking about phones here). The discussion was simply on biometrics beyond Windows Hello since its been pretty clearly stated how Windows Hello will use and store the data.
  • They can fit a real sense camera in to a Dell Venue 8 7000​ tablet that is only 6 mm thick so why would they not be able to put one in a much bigger surface pro 4?
  • Why not just include a fingerprint scanner, like everyone else...If I have to hold my phone up to my face to unlock it, I won't use it.
  • He said "arm's length" so you won't have to hold it up to your face. You'll just have to hold it, and the screen will have to roughly point at your eyes. That doesn't sound so bad, does it? I'm sure they'll have fingerprint readers too, in the future. But of course those will require you take off gloves and put the right finger in the right place, so everything has a downside.
  • Cool!
  • Thanks for the write up Dan ;)
  • Does Lumia 930 will have this iris scanner feature when windows 10 mobile comes out ???
  • No. Unless you wish to switch on the lights at night everytime to use your phone.
  • There's a joke in there somewhere... Can't say facial around me without getting a giggle... Posted via the Windows Central App for Android
  • Face unlock got really good on android lollipop but you still had to activate your device and get to the lock screen before it would see your face and unlock.
    I'm hoping that the iris scanner is ( by user option) always on and so you just need to pick up your 950(xl) look at it and it unlocks to start screen......that would be a great step forward and give WM10 a unique feature.
  • I'm afraid that would not be fesible, you'd have to have CPU running all the time, which would mean 4-8 hour battery life, or less. With this, you should just have to turn the screen on for it to work. The advantage over Android's face recognition is that this won't mistake a picture or twin for you, and it will work in the dark, or when you're wearing glasses or your hair looks different. Android needed good lighting, lining your face up. getting the right angle, no hats or new hairstyles, etc.
  • Android needed the Lumia 550's front facing flash! ;-) Although I'm sure there are front-flash android phones. I wonder if the light from the phone's screen will be sufficient for iris scanner to work in pitch dark.
  • Very well explained, easy to read. Thanks.