It's hard to hide the front shot! What's so hard about the under-screen camera?

In the matter of "killing" the front camera, mobile phone manufacturers have made many attempts to achieve the art of "a complete screen". OPPO Find X, OnePlus 7 Pro, etc., using a lifting structure to hide the front camera; ZTE Axon 20, Xiaomi Mi MIX 4, etc., choose the under-screen camera solution; Of course, there are also dual-screen versions such as Nubia X and vivo NEX that use dual-screen designs, which physically remove the front camera.

The ideal is very full, the reality is very skinny, or heavy, or fragile, or inconvenient, and the under-screen camera solution has become the final effort of manufacturers to hide the front camera. However, after the difficult consumption winter, no one dares to take any more risks, and only ZTE is left in 2023 that will still use the under-screen camera solution design. From the favored competition to release the concept machine under the screen, to the recognition of reality and the return to the digging screen design, in the game of trade-offs of the under-screen camera solution, what is difficult for mobile phone manufacturers to hide?

Hidden camera "sad to climb to the sky"

Admittedly, at the moment, the under-display camera solution is the only solution that can strike a balance in all aspects and still provide the most perfect look, but the development of this technology does not seem to be as fast as we think.

The author has long used the "true full screen" mobile phone OnePlus 7 Pro with a lifting camera solution, and its QHD+ resolution, combined with the look and feel experience of no digging holes and no bangs, makes it difficult for the author to give up. But the mobile phone has to be replaced after all, the old performance, the mechanical structure caused by the inability to waterproof, etc., make the author feel a lot of inconvenience in daily use.

(OnePlus 7 Pro with "true full screen" mobile phone with lifting camera solution)

At that time, many manufacturers had launched the concept of using the under-screen camera solution, which made the author feel that the future was in front of me at that time, and it seemed that as long as more time was given, mobile phone manufacturers could launch a perfect mobile phone with QHD+ resolution and completely hidden under-screen camera.

But until today, most mass-produced mobile phones that use under-screen cameras will "show their stuffing" as soon as the screen is lit, and some of the poor effects even make many people feel that it is better to use a digging screen. Even ZTE, which is still insisting on it, can only maintain the resolution at FHD+, and it has to hide the camera more perfectly in some cases.

(ZTE's Nubia Z50 Ultra front hidden effect under the screen from Up master Zhong Wenze)

Again, the rationale for this programme is the rationale.

First of all, the under-screen camera scheme is to hide the front camera, definitely not to make the front camera unavailable, even if many people say that it is possible to make a mobile phone without a front camera, but more people still need a front camera with good imaging effect for selfies, video calls, etc.

And good imaging results, need light, need a lot of light. But at this time, a screen was blocked in front of the camera.

At present, the vast majority of mobile phones on the market use OLED screens, which benefit from its many new features and gradually eliminate the previous LCD screens. However, the OLED screen itself is opaque. At this time, it is necessary to let the light pass through the OLED screen and let the camera get the light.

(Schematic)

In 2020, ZTE launched the world's first under-screen camera mass production mobile phone Axon 20, which adopts Visionox's "InV see" solution, which can be regarded as the beginning of the under-screen camera mobile phone. Another representative under-screen camera solution mobile phone is Xiaomi's MIX 4 launched in 2021, which uses TCL Huaxing's solution.

The basic principle of both schemes is to redesign the pixel arrangement and driver circuit of the screen corresponding to the photosensitive area of the front camera under the screen. Visionox uses two arrangements: "small delta + delta", and TCL Huaxing is "small pearl arrangement + pearl arrangement". This change allows the original pixel area to be reduced in a certain proportion, and part of the original pixel position becomes a blank part that is not displayed, so that part of the light can pass through and reach the camera.

(Visionox Solution and TCL Huaxing Solution)

However, the change of pixel arrangement, and the change in pixel area caused by such a change, will really affect the effect of screen display. The pixel area is reduced, resulting in a blurry look and feel in that area, and the brightness is not as high as the normal screen, so it needs to be brightened separately, and individual brightening brings a variety of problems, such as burn-in screen. This is a pixel residual image phenomenon caused by the long-term use of OLED at high brightness, which cannot be avoided. Not only that, the high brightness of small areas also brings problems such as uneven brightness and color in terms of perception.

(Under-screen front effect on Samsung Galaxy Z Fold4)

At the same time, the high requirements for the number and area of pixels mean that QHD+ resolution screens with more pixels are basically not related to under-screen cameras.

Tossing so much also brings more derivative problems, which is really not worth the loss.

In 2023, the Z50 Ultra launched by ZTE's brand Nubia uses the Visionox under-screen camera solution, which has been iterated to the fourth generation. Its actual look and feel has achieved that most of the display content is not perceived by the under-screen camera, but its screen resolution is only just over FHD+, and it is not even "1.5K".

And, even if I don't care about resolution, is it enough to be perceptible on the display?

"Comes with Holy Light Special Effects"

In fact, before choosing the OnePlus 9 Pro I use now, I first chose the Xiaomi Mi MIX 4 and used it for about a week. Because the author once naively felt that with his "persistence" that the mobile phone must be "true full screen", he could overcome many problems of Xiaomi Mi MIX 4, such as the lack of QHD+ resolution and the looming camera under the screen. But the author thought too simply.

Many people have suggested that manufacturers launch a mobile phone without a front camera, so that it can easily achieve a true full screen. Even if a person does not take selfies or video calls, government affairs and financial services are always needed. At a time when many government affairs and banking services require face verification, I believe that some people may not be able to say things like "no front camera" again.

The main reason why the author later returned the Xiaomi Mi MIX 4 and chose the OnePlus 9 Pro digging screen mobile phone was that the front camera imaging effect on the MIX 4 at that time was simply too poor. How bad is it? Just look at the real picture.

(The author used the Xiaomi Mi MIX 4 front shooting effect at that time, the front image was very blurry and flooded badly)

This is a very "fatal" problem.

OLED's improved light transmittance is only 5%-20%, far less than 90% of the digging screen mobile phone. Even in very good light, there is very little light that can enter the front camera. Without enough light, the photographic effect will be full of noise and smearing, and when the shooting environment is dark, the imaging effect of the front camera under the screen is even more "unbearable".

Secondly, there is a phenomenon of "diffraction" of light in physics. Simply put, light will bend to varying degrees after passing through obstacles such as slits, holes or discs.

(Schematic)

The front scheme under the screen changes the pixel arrangement, reduces the pixel area, although the light can pass through, but the gap between the pixels on the screen is very small, and countless grids are formed between pixels, which means that diffraction will occur. Moreover, the light produces more rays after being divided by the grid, and the light is divided again, producing more diffraction, which leads to the use of the front camera under the screen will find itself with a layer of "halo" and "hazy" feeling, which was jokingly called "holy light" when the under-screen camera mobile phone first emerged. It is even more serious if shooting in the case of backlighting.

(Netizens measured the backlit shooting effect of the camera on the screen)

All kinds of problems are limitations brought about by the laws of physics, and it is difficult to change.

From the first generation to the current fourth generation of the program, ZTE has switched to sensors with stronger and stronger photosensitivity in its own products, and has also developed a "front camera penetration algorithm" specifically for the problem of "foggy" and "holy light" under the screen, through AI to reduce the noise of imaging, real-time calibration of the picture in different light environments, intelligent de-fogging, intelligent anti-glare, to improve imaging clarity and transparency.

But again, the laws of physics are difficult to break through.

(ZTE official website pre-algorithm introduction page)

Is "front under the screen" really the optimal solution?

In fact, having said so much, the display effect and the imaging effect are ultimately a contradiction between "fish and bear's paw". Just as many people want a small size and a small screen mobile phone, but want a long battery life and a large battery is so contradictory, under the current development of science and technology, it can only be done to give up one thing in exchange for another thing.

Strong as Samsung, after using a short generation of "front under the screen", it returned to the digging screen; Apple even began to use Liu Haiping from the iPhone X to 2022 to switch to the digging hole "Spirit Island", during which it did not consider the "front under the screen" solution; At present, only ZTE is struggling to insist on domestic manufacturers. Not only have manufacturers abandoned it, but the essential problems such as the sharp increase in the cost of the "pre-screen solution" and the bottom yield rate will still exist in 2023. In my opinion, this is definitely not the optimal solution. 

Sometimes compromise is often a better choice, just like the author from obsessing with the "true full screen" to buying a cut-out screen mobile phone, since now you can't make the front lens disappear, then make the front lens smaller by reducing the area of the hole, adopt a folding screen design, turn over, and use the rear lens to take a selfie. Sometimes compromises often create new outlets. 

But whether it is a manufacturer or a user, in fact, everyone feels that the digging screen will definitely be eliminated, but the time has not come. But what kind of new form of mobile phone is eliminated? Or is there a major breakthrough in "under-screen camera" technology? This can only be answered by time.