Xiaomi MIX 4 with my own eyes: a sub-screen front camera that you really can't see

By: Alex Chub | 29.10.2021, 15:31
Xiaomi MIX 4 with my own eyes: a sub-screen front camera that you really can't see

Time flies very fast and it has already been five years since Xiaomi Mi MIX was announced. The first representative of the MIX line, which has always been famous for experimentation. The first model was interesting with virtually no frames on the top and sides of the screen. The front camera was tucked under the screen, and a piezo speaker in the screen was used instead of the classic conversation speaker. We cannot say that Xiaomi Mi MIX became the "ancestor" of frameless smartphones (Sharp produced similar models before, but they hardly ever went outside Japan), but it was definitely a kind of popularizer. Xiaomi Mi MIX 3 was interesting design-slider with a hidden front, Xiaomi Mi MIX Alpha and even got a screen that wraps around the body. The current Xiaomi MIX 4 is not as experimental, but it also has a number of interesting features. In particular, the updated flagship Qualcomm Snapdragon 888+ processor, ultra-fast 120W charging (which we've already seen in action in the Xiaomi 11T Pro) and a ceramic body. But the most interesting feature was the sub-screen front camera. This is the first time Xiaomi uses it in its smartphones. And in general, there are only a few such smartphones on the market so far, and the implementation is not the best. Notable examples are the ZTE Axon 30 5G and the Samsung and Galaxy Z Fold3. Xiaomi MIX 4 will not be sold in our country, but the editorial gg managed to get a sample and get to know it better. First of all, with its sub-screen camera, which is particularly interesting.

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There is not much sense in the full-fledged review both because of the difficulty of purchasing the smartphone and because we have had a sample with a crude version of the firmware. But there is a lot to tell.

Quick link:

  1. What is interesting about the front camera of Xiaomi MIX 4?
  2. How visible and how does this camera shoot?
  3. What does the smartphone itself look like?
  4. What are the specs of Xiaomi MIX 4?
  5. What is the main camera interesting?
  6. In a nutshell

What is interesting about the front camera of Xiaomi MIX 4?

The main difference between the implementation of the sub-screen front camera in Xiaomi MIX 4 from the competitors is that the pixel density is the same as the rest of the display: 400 pixels per inch, using semi-transparent sub-pixels. That said, the area with the front camera is, of course, translucent for shooting and it's slightly enlarged to capture more light. The pixels in the camera area itself are turned off during filming. According to Xiaomi, all these features have made the camera virtually invisible. Xiaomi calls its technology very obviously: Camera Under Panel or simply CUP. It took around 5 years to develop and a lot of patents were taken out. This is already the 3rd generation of Xiaomi's proprietary Camera Under Panel. Apparently, the previous generations were not too successful. The resolution of the camera is 20 megapixels.

The reverse side of the coin the technology also has. Despite the fact that the Xiaomi MIX 4 is essentially a flagship, albeit not for everyone, the display resolution is FullHD. With a 2K display, the pixel density above the front camera would be significantly lower and it would be more noticeable. And the second point, which during the presentation the company itself said: the Xiaomi MIX 4 is not a smartphone for those who like to take a lot of selfies. In other words, the company admitted that the quality of pictures on the sub-screen camera is not the best. Let's take a look at what the result is.

How visible and how does this camera shoot?

Marketing by marketing, but the average user cares more about how it works in reality. And to give credit to Xiaomi's engineers, this is currently the best implementation of a sub-screen camera that we've seen. And probably the best implementation of any commercial smartphone available right now. The camera when the screen is active really isn't visible most of the time.

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For the most part, the front camera area is visible thanks to the factory protective film, which has a hole in the appropriate place. Otherwise, the front can only be seen except at a certain angle in bright light. In a word, the realization is impressive. Aesthetes, whose sense of beauty is hurt by holes in the screen, will definitely be pleased. It seems that in a couple of years the technology will allow for truly invisible under-screen cameras with decent image quality and we will see them not as an isolated case but en masse as happened with under-screen fingerprint scanners.

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As for the shooting quality of the front camera, Xiaomi told the truth. It really does shoot far from perfect. For fans of posting tons of selfies on Instagram is clearly not suitable. But for video calls and video conferencing it will definitely be enough.

What does the smartphone look like?

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The main thing that catches the eye when you first look at the smartphone is the same front camera. Or rather its absence and the screen without any cutouts or openings. Otherwise, Xiaomi MIX 4 looks like a typical modern flagship smartphone. The screen in the entire front panel with minimal bezels and small curves on the sides. The rear panel of the smartphone is ceramic. This is probably one of the reasons that the smartphone turned out to be quite weighty: 225 g. The tactile ceramic is very pleasant and different in feel from glass. The color is interesting: it is not quite white and under different lighting goes slightly to gray or blue shades. It is glossy, but prints are almost invisible.

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The functional elements on the ends of the smartphone are placed as usual. On the right side there are the power and volume control buttons, while at the bottom there is a tray for two SIM cards, a microphone, a speaker and the Type-C connector for charging. On the top end there are a stereo speaker hole, microphone, IR port and the logo of harman/kardon, which is somehow involved in the sound of the smartphone.

The main camera of the smartphone is also interesting in terms of features. In particular, there is a periscopic telephoto module. But as a result, the rear camera module itself is quite massive and protrudes noticeably above the body of the smartphone. This is partially solved with a case. And in general, all top-of-the-range camera phones suffer from this. But the solution with the module in the full width of the body, as in Xiaomi Mi 11 Ultra seemed more aesthetically pleasing to me.

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The smartphone looks aesthetically pleasing and feels expensive. Only one complaint: in fact, Xiaomi MIX 4 belongs to the flagship class of devices. But the protection received only IP53. In this case, the competitors' flagships, and the aforementioned Xiaomi Mi 11 Ultra have IP68 protection.

And what about the characteristics of Xiaomi MIX 4?

The smartphone has a 6.67-inch AMOLED screen with a resolution of 2400x1080 (aspect ratio 20:9) and a pixel density of 395 ppi. It supports a refresh rate of 120 Hz. Claimed maximum brightness of 800 cd/m2, the screen supports HDR10 +, Dolby Vision. Visually the screen is very good, brightness is enough for comfortable use in the sun, colors are saturated.

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In terms of internals, the Xiaomi MIX 4 is all right. The processor is the updated flagship Qualcomm Snapdragon 888+ processor with increased frequencies. To be precise, the main difference from the Snapdragon 888 is the increased maximum frequency of the most productive Cortex X1 core from 2.84GHz to 2.995GHz, so the overall performance has increased from 26 to 32 TOPS (trillion operations per second). Otherwise, it's business as usual. It's a 5nm octa-core with Kryo 680 cores: 1x2.995GHz, 3x2.42GHz and 4x1.8GHz. The Adreno 660 accelerator is responsible for the graphics. There can be 8GB or 12GB of RAM and 128GB, 256GB or 512GB of UFS 3.1 type built-in memory. So that the smartphone has no problems with performance.

In terms of communication capabilities. There's dual-band Wi-Fi with support for the new Wi-Fi 6e standard, Bluetooth 5.2 with aptxHD codec support, NFC, UWB and an infrared port to control electronics. The smartphone produces a pretty loud mi clear stereo sound. For navigation there is support for A-GPS, GLONASS, GALILEO, BDS, QZSS and NavIC. Powered Smartphone from a relatively small battery of 4500 mAh. It supports the proprietary 120W fast charging, as in Xiaomi 11T Pro. The smartphone can be fully charged in 15 minutes. There is also support for the branded 50W wireless charging. As the OS is installed Android 11 with the MIUI 12.5.7 shell. Of course, the version for China without Google Play and generally Google services as such.

What is interesting about the main camera?

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The rear camera includes three modules. The main one - 108 megapixels ISOCELL Bright HMX size 1/1.33", 1.6 microns, aperture f/1.9, there is optical stabilization, laser and phase autofocus Dual Pixel PDAF. The periscopic telephoto camera has a resolution of 8 MP, has autofocus and optical stabilization. It provides 5x zoom. The ultra-wide-angle module has a resolution of 13 MP, an aperture of f/2.2, a viewing angle of 123 °. We had a sample in which (apparently) is rather crude firmware and the camera worked a little strange, especially it concerns the night mode of shooting. But anyway, you can check out some examples of the camera's work below. Main camera:

Ultra wide-angle:

5x zoom:

In summary

Getting to know the Xiaomi MIX 4 cannot be called a complete experience. Both because of the modest timing, and because of the Chinese firmware, with which in our realities to use the smartphone as a primary is extremely difficult. But it's safe to say that the smartphone turned out to be very interesting. Including thanks to the finally almost invisible front camera under the screen. The technology is very promising and, I suppose, in a couple of years we will see similar cameras in more mainstream models. Otherwise, the smartphone also didn't disappoint: top specs, great display, nice design with a ceramic back cover, decent main camera and incredibly fast wired charging. Unfortunately, Xiaomi decided not to take the risk and limited the geography of sales Xiaomi MIX 4. In Ukraine it will not be, although the audience would definitely be found.


Specifications Xiaomi MIX 4
Display OLED, 6.67 inches, 2400x1080 (aspect ratio 20:9), 395 ppi, 120 Hz, HDR10+
Case dimensions: 162.6x75.4x8 mm, weight: 225g
Processor 64-bit octa-core 5nm Qualcomm Snapdragon 888+: 1x2.995GHz Kryo 680 + 3x2.42GHz Kryo 680 + 4x1.80GHz Kryo 680, Adreno 660 graphics
RAM 8/12GB
Flash memory 128/256/512GB UFS 3.1
Camera Main: 108 MP, f/1.9, 1/1.33", 0.8µm, Dual Pixel PDAF, Laser AF, OIS; ultra-wide angle: 13 MP, f/2.2, 123˚; periscopic telephoto: 8 MP, f/4.1, PDAF, OIS, 5x zoom; Video: 8K@24; Front camera: 20 MP sub-screen
Wireless technologies Wi-Fi 802.11 a/b/g/n/ac/6e (dual band, 2.4 and 5 GHz), Bluetooth 5.2 LE, aptX HD, NFC, UWB, IR port
Battery 4500 mAh, non-removable; 120W fast charging, 50W wireless fast charging
Operating system Android 11 + MIUI 12.5
Sim card 2xNanoSIM
Optional dust and moisture protection IP53, under-screen fingerprint scanner

For those who want to know more