Scanner in Xiaomi Redmi: how it works, how it works and how to configure

Biometric scanners in Xiaomi Redmi smartphones are no longer a luxury — today it is a security standard that combines convenience and reliability. But how exactly does this mechanism work? Why sometimes a print is not read the first time and facial recognition fails in the dark? In this article, we will discuss the technical principles of scanners at Redmi, from optical and ultrasonic sensors to machine learning algorithms that analyze your biometric data.

You will learn what types of scanners are used in different Xiaomi models (from the budget Redmi Note to the flagship Redmi K), how they are integrated into hardware and software, and get practical tips on how to adjust and fix typical problems.

Types of scanners in Xiaomi Redmi smartphones: a comparison of technologies

Xiaomi Redmi uses three main types of fingerprint scanners and two types of facial recognition systems, and the choice of technology depends on the model and its price segment.

• 🔍 The optical scanner is the most common in budget models (like the Redmi 10A or the Redmi Note 11) and works by taking a backlit photograph of the fingerprint, then the algorithm compares the image to the stored pattern.
• 📡 Capacity scanner -- used in the middle segment (like the Redmi Note 12 Pro) -- reads the electrical charge of the skin to form a 3D- map of papillary patterns, more accurate than the optical, but sensitive to moisture.
• 🌊 Ultrasonic scanner — found in flagships (e.g., Redmi K60 Ultra) Uses sound waves to create a three-dimensional image of a fingerprint, even working with wet or dirty fingers.
• 👤 Face recognition 2D/3D — budget models use 2D- scanning (photo analysis), premium models use 3D- scanning with infrared illumination (for example, in Redmi K50 Pro).

Every technology has its pros and cons. For example, optical scanners are cheaper but less reliable in bright light or with damaged fingers; ultrasonic scanners are more accurate but consume more power; and facial recognition systems in budget models can be fooled by photography, whereas 3D- scanners will not allow this.

⚠️ Warning: In Redmi models with AMOLED- screens (e.g., the Redmi Note 12 Pro+), the optical scanner is often embedded under the display. Such sensors require more careful handling - scratches on the screen can impair the reading of the fingerprint.

How a fingerprint scanner works: from reading to recognition

The process of fingerprint recognition in Xiaomi Redmi can be divided into three stages: read, process and compare. Let's break down each of them.

In the reading phase, the sensor captures a unique pattern of papillary lines. In optical scanners, this is done by LED backlighting that illuminates the finger, and the sensor captures reflected light. In capacitive scanners, the sensor analyzes the change in electric field when you touch the skin. Ultrasound scanners send sound waves that bounce off different layers of skin, creating a 3D- image.

The data is then transferred to a secure enclave (a special chip isolated from the main system), where the algorithm converts raw data into a mathematical template. Importantly, Xiaomi does not store the image of the fingerprint itself, only its encrypted version. With each new scan, the system compares the current template with the stored data.

If the match exceeds the threshold (usually 70-90%), the smartphone will unlock, otherwise you will see an error message. Interestingly, in some models (for example, the Redmi K40) you can adjust the sensitivity of the scanner, which is useful if you have thin or damaged skin.

Face recognition in Redmi: how a smartphone sets you apart from a photo

Xiaomi Redmi's facial recognition systems are divided into two types: 2D (flat image analysis) and 3D (building a three-dimensional model), the former used in budget models and vulnerable to photo cheating, the latter, like the Redmi K50 Pro, use infrared backlight and deep sensors, making them more reliable.

The algorithm of the 3D- face scanner:

1. The infrared projector creates a grid of 30,000 points on the user’s face.
2. The infrared camera reads distortions of this grid caused by the relief of the face.
3. The system builds a 3D- model and compares it to the saved template.
4. If the match is sufficient (usually 80-95%), the smartphone will be unlocked.

An important nuance: Xiaomi uses liveness detection technology. The algorithm analyzes facial micro-movements (blinking, expression change) to distinguish a live person from a photograph or mask. However, in cheap models, this feature is simplified, so they can be fooled by a quality 3D- layout.

⚠️ Warning: If you use facial recognition in Redmi with a 2D- scanner, avoid storing photos of your face in the public domain (social media, clouds).

Where is biometric information stored and how secure is it?

Many Xiaomi Redmi users worry about the security of their biometrics. Unlike passwords, fingerprints or facial features can't be changed if they're compromised. Let's look at how Xiaomi protects that information.

All biometric data is stored in TrustZone, an isolated area of the processor that is not accessible to the main operating system and applications, and even if a hacker gains root access to the smartphone, he will not be able to extract the fingerprint in its original form.

• 🔐 Hardware encryption – data is encrypted using a unique key tied to a chip.
• 🛡️ Interception protection – biometric data is never transmitted over the network (even when synchronized with Mi Account).
• 🔄 Dynamic patterns – algorithms periodically update mathematical fingerprint models to make it harder to copy them.

However, biometric authentication is not completely reliable. For example, in 2022, researchers proved that some optical scanners in budget Redmis can be fooled by high-quality imprint casting, so it is better to use a PIN or password for critical operations (bank payments, access to corporate data).

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If you sell or transfer your Xiaomi Redmi to another person, be sure to delete all biometrics from the Settings menu → Passwords & Security → Delete biometrics.

Typical scanner problems in Redmi and how to fix them

Even the most reliable scanners sometimes fail, and let’s look at the most common problems in Xiaomi Redmi and how to solve them.

1. The fingerprint scanner doesn't recognize the finger.

Reasons:

• 🧴 Dirt or fat on the sensor/finger.
• 💧 Wet hands or sweating.
• 🩹 Skin damage (cuts, calluses).
• 🔋 Battery discharge (some scanners are turned off when the charge is low).

Decisions:

Wipe the sensor and finger with a dry wipe.|Reboot your smartphone|Remove and re-add the print|Check your sensitivity settings (if available)-->

2 Facial recognition is not stable

If your smartphone doesn’t always recognize your face, try:

• 🌞 Adjust lighting — 2D- scanners don't work well in the dark.
• 👓 Remove glasses or headgear (they may distort facial features).
• 🔄 Add an alternative look (in some models, multiple face angles can be saved).

3.The scanner under the screen is slow to respond

In models with a subscreen scanner (e.g. Redmi K50), delays can be associated with:

• 📱 Damaged oleophobic screen covering (scratches, chips).
• 🔋 Energy savings (turn off battery mode in settings).
• 📲 Outdated firmware (update MIUI via Settings → About Phone → System Update).

⚠️ Warning: If the scanner stopped working after falling or getting moisture, don't try to disassemble the smartphone yourself. At Xiaomi Redmi, sensors are often integrated into the display or back panel, and their replacement requires special equipment.

How to improve the scanner: tips and hidden features MIUI

Many users are unaware that MIUI has hidden settings that optimize biometric sensors, and here are some useful tips:

1. Adjust the sensitivity of the fingerprint scanner

In some models (for example, Redmi Note 12 Pro+) you can change the sensitivity of the sensor:

1. Go to Settings → Passwords and Security → Fingerprint.
2. Select the saved print and tap on the scanner settings (if the option is available).
3. Try to reduce sensitivity if the scanner is too easy (the risk of false positives), or increase if the finger is not recognized the first time.

2. Addition of alternative fingerprints

If you have trouble recognizing one finger (for example, because of a scar), add the same finger at a different angle or another finger.

3. Accelerating facial recognition

In models with 3D- face scanner (for example, Redmi K60) you can enable the option to unlock when lifting:

• Go to Settings → Lock screen → Face recognition.
• Activate the option to raise to unlock.
• The smartphone will automatically scan your face when you lift it.

4. Biometric data dumping

If the scanner is not working properly, try a full reset:

1. Delete all fingerprints and facial data in Settings → Passwords and Security.
2. Reboot your smartphone.
3. Add the biometrics again.

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Regularly update MIUI – in new versions of the firmware Xiaomi improves recognition algorithms and corrects scanner errors.

The future of biometrics in Xiaomi: what to expect in the new models of Redmi

Xiaomi is investing heavily in biometrics, and the following innovations are expected in the upcoming Redmi models:

• 👁️ The iris scanner is already being tested in prototypes, more specifically facial recognition, and it works in total darkness.
• 🧬 Palm venous analysis is a technology that reads the unique pattern of veins under the skin. It's almost impossible to fake.
• 🤖 AI optimization – neural networks will analyze user habits (e.g., typical unlock time) and adapt the sensitivity of the scanners.
• 🔋 Energy-efficient sensors – new scanners will consume 30-40% less power, which is important for low-end models.

Xiaomi is also working on integrating biometrics with Mi Pay and other payment systems, which can be confirmed with fingerprints in some regions, but will become the standard for all Redmi models in the future.

Another area is multimodal authentication, where the smartphone will combine multiple biometric data (face + fingerprint + voice) to improve security without compromising convenience.

FAQ: Frequent questions about scanners in Xiaomi Redmi