Owners of the last generation of flagship devices often wonder how to make the most of biometric protection in their gadgets. Xiaomi Mi8 was one of the first devices of the brand to receive full support for face unlock, implemented through an infrared sensor, not just through the front camera. This provides not only speed, but also security, allowing you to use the function even in complete darkness when ordinary cameras are blind.
However, the standard activation path through the settings menu is not always obvious to all users, and some hidden features are left out of the limelight. In this guide, we will detail the scanner switching on algorithm, IR diagnostics, and the nuances of how MIUI works with biometrics. You will learn why the function may not be available in some cases and how to check the health of the complex sensor module at the top of the screen.
Getting Face Unlock right makes smartphone use a comfortable experience where the screen lights up instantly as soon as you pick up the device. We'll look at the technical aspects of the IR dot projector that creates a three-dimensional map of your face, and explain the difference between standard unlocking and advanced security modes. Get ready to dive into a world of settings that many people don't even know about.
Technical features of the unlock module
Unlike most modern budget models that use software emulation through a conventional camera, Xiaomi is a very popular model. Mi8 It's equipped with a complete hardware system, and in the top bang of the display, there's an IR proximity sensor, an IR camera, and a point projector. 3D-a user's face relief map, making the system resistant to deception with photos or screens from other phones.
The module doesn't depend on external lighting, because it generates the required infrared field. When you press the screen, the projector emits thousands of invisible dots that are read by the sensor. The neural network algorithms instantly compare the resulting cast to a reference that is stored in a protected area of the processor, which provides a response rate comparable to that of a fingerprint scanner, but without the need for physical touch.
⚠️ Warning: Do not try to seal the top of the screen ("bangs") with tight protective glasses with a black frame that overlaps the sensors. This will cause the IR lighting to reflect off the sticker, and the system will cease to see the face even under ideal lighting conditions.
It’s important to understand that the hardware implementation in the Mi8 is more reliable than its software counterparts, but it requires greater accuracy in positioning the smartphone relative to the face. If it is unlocked from any angle under normal conditions, the IR module has a limited field of view, which is a compromise for the sake of increased data security.
Why is an IR sensor better than a regular camera?
Step-by-step instructions for activating Face Unlock
The process of enabling facial unlock in the MIUI shell is standardized, but requires care during the biometric input phase. First, go to the main system settings menu, find the Password and Security section, which is usually located at the top of the list or in the System Applications and Settings group.
Next, select Face Unlock. The system will request confirmation of action, warning that this method is less safe than PIN, but easier to use. Press Add Face Data. You will be asked to hold the phone at a distance of 20-40 cm from your face and slowly turn your head so that the camera can read different angles.
☑️ Pre-activation check
After a successful scan, the system will suggest setting additional settings, where you can activate the option “Unlock when lifting the phone” or “Stay in unlock mode while I look at the screen.” Also in this menu is the Use Face ID switch, which should be in the active position to operate the function on the locked screen.
If the process is successful, you will see a notification, and now when you click on the lock screen or raise the smartphone, the device will instantly go to the desktop. In the event of a scan error more than three times in a row, the system will require you to enter a pattern lock or a digital password to confirm the identity of the owner.
Diagnostics and verification of IR sensors
Sometimes users are faced with a situation where the function is turned on but not working, in which case you need to diagnose the hardware. In Xiaomi Mi8, there is an engineering menu available through a set of special code in the Phone application. Enter the combination ##6484## to go to CIT testing mode.
In the list of tests, find the item associated with Infrared or Face ID. Once you run the test, you can see if the sensor reacts to your presence. The engineering menu also allows you to check the work of the dot projector: in the dark, through the camera of another phone (which sees the IR spectrum), you can see a purple glow in the “bangs” area when the screen is activated.
| Component | Function | Sign of malfunction |
|---|---|---|
| IR camera | Image reading | Mistake "I failed to recognize the face" |
| Point projector | Construction 3D-map | Unlocking only in bright light |
| Light sensor | Brightness adjustment | The screen does not go out in the ear when ringing. |
| Dynamicspiece | Sound output | The interviewer can't hear you. |
If the engineering menu doesn't pass the tests, the problem is probably physical damage to the plume or the module itself. In the Mi8, this node is integrated into the top of the display module, and replacing it requires skill, and software resetting rarely helps restore the hardware sensors to work.
Hidden settings and additional features
The MIUI shell hides a few useful features that are not obvious when you first meet them, such as the ability to configure notification behavior on a locked screen in conjunction with Face ID. If the feature “Show the contents of notifications” is activated, the text of messages will be hidden until the camera recognizes your face.
You should also pay attention to your app security settings, and in the Application Protection section, you can choose the method of unlocking for specific programs, and by choosing Facebook ID, you can open a banking app or gallery with a photo at a glance without entering a password every time, which greatly speeds up the work with sensitive data.
⚠️ Attention: Unlocking applications via Face ID Xiaomi Mi8 This can be slower than unlocking the screen itself, due to Android security priorities, which require additional authorization to access app data.
Another interesting feature is the possibility of using a person for authorization in payment systems, although in the case of a person with a certain number of users, Mi8 It's a very limited process. Some banks allow Face to be used. ID to enter the application, but require input PIN-It's a trade-off between convenience and financial security.
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Use Guest Mode in your face settings if you want to give someone a phone to call, which will limit access to the call feature, hiding the rest of the data.
Solving recognition problems
The most common problem is that the system fails to recognize the wearer in glasses or when you change your hairstyle. MIUI algorithms are adaptive, but they take time to learn. If you change your image, it's recommended that you delete old facial data from your memory and write down a new profile, which is especially true for users wearing thick-rimmed or polarized lenses.
Another common situation is a slow reaction or “blinking” of the screen when trying to unlock, which may indicate a lack of CPU resources in the background or a conflict with established design themes. Try to temporarily switch to a standard theme and check the work of the face scanner. If the problem disappears, then the third-party theme contained errors in the code of the screen locker.
In rare cases, after updating the firmware, the biometrics settings may get lost. If the function is missing from the menu or becomes inactive (gray), perform a full reset of the phone settings. Before that, make sure to back up the data, as this step will remove all information from the device, but return the system to a factory state with the correct drivers.
- 👓 Glasses: Sunglasses can block IR radiation, making unlocking impossible.
- 🌑 Darkness: Unlike conventional cameras, an IR sensor Mi8 It works in complete darkness without restrictions.
- 📸 Masks: Medical masks cover key facial points, so the system will require a password.
- 🔄 Updates: After resetting or flashing, always re-enter face data for calibration.
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Deleting and re-recording facial data solves 90% of software recognition errors, especially after changing appearance or accessories.
Comparison of data protection methods
Users often argue about whether the face or fingerprint is more reliable. In the case of the Xiaomi Mi8, we are dealing with a unique situation where full-fledged IR unlock is implemented, which puts it above conventional software counterparts.
Face ID wins in scenarios where your hands are busy or dirty. You don't have to wipe your fingers or look for a button, just look at the screen. On the other hand, in a stressful situation or in poor light (if the IR sensor is contaminated), the finger can work more reliably. The ideal option is to use combined protection.
From a security perspective, an IR scanner Mi8 protects better than 2D-The cameras are inferior to the ultrasonic fingerprint scanners built into the screen of the new flagships, but for everyday use and protection from accidental access by unauthorized persons, the level of protection is not limited to the security of the new flagship. Mi8 more than enough.