E4 material, HDR 10+, 8192 level dimming…how much do you know about the phone screen parameters?

The screen is the main window for human-computer interaction. The quality of the screen almost determines the experience of using a mobile phone.

Fortunately, since the iPhone 4 started the "retina screen" trend, more and more manufacturers have begun to pay attention to the user's visual experience. The screen size is bigger, the frame is narrower, the bangs are smaller… These are not enough. At the new machine launch conference in the past two years, manufacturers have begun to emphasize parameters such as screen material, contrast, and color.

For example, the Xiaomi Mi 11 series, known as the "2021 flagship goalkeeper", has put a lot of effort in the promotion of screen quality: Samsung E4 material, 5000000:1 contrast, 1500nit maximum brightness, 2K+120Hz and so on. Lei Jun stated that this is "the most expensive and best screen ever made on Xiaomi phones."

▲ Mi 11 screen poster

In the iOS camp, the super retina XDR screen on the iPhone 12 series supports playback of Dolby Vision video and HDR display, refreshing the iPhone’s look and feel. Apple calls this screen "an ocean of pixels" on its official website.

Although the manufacturers are very active in publicity, but for ordinary users, these numbers and proper nouns are still a bit difficult to understand. We tried to use easy-to-understand language to analyze the screen parameters of these two "benchmark phones" together, whether it is a gimmick or a real skill.

Screen parameters, not so difficult to understand

Integrating the official Weibo and official website of Xiaomi mobile phones, as well as the publicity of Apple's press conference and official website, we can see that the two main points of promotion of the screen quality are as follows.

First look at "luminescent materials". One of the characteristics of OLED screens is that each pixel can emit light independently without a backlight. Therefore, the luminescent material greatly affects the power consumption and display effect of the screen.

The E4 used in Xiaomi Mi 11 is Samsung's latest OLED light-emitting material. Compared with the previous generation of E3 materials, the main upgrade points of E4 are peak brightness, contrast and power consumption. For example, the local peak brightness of Mi 11 soared to 1500nit, the contrast was upgraded to 5000000:1, and the power consumption was reduced by 15%.

Although the iPhone 12 also uses OLED screens in all series, there is no official information about its luminescent materials.

Then we look at "resolution" and "pixel density". The resolution of the screen refers to the number of pixels displayed on the screen, generally expressed as the number of horizontal pixels × the number of vertical pixels. Under the same size, the higher the resolution, the more delicate the look and feel, which involves the pixel density.

Jobs first proposed the Retina screen at the iPhone 4 conference, indicating that the iPhone 4's screen pixel density is 326ppi, which exceeds the 300ppi limit of human eye recognition.

However, this definition is conditional, that is, the user's vision is 1.0 and the viewing screen distance is 20-30cm. In fact, the vision of some people may be higher than 1.0, and the screen will be closer to the human eye. According to the data of GuoKai.com, the actual resolution of most people's eyes should be as high as 450ppi or more.

The pixel density of Xiaomi Mi 11 and iPhone 12 Pro Max is higher than 450ppi. If you don't look at it with a magnifying glass, it is difficult for the human eye to perceive the difference in delicacy between the two.

▲ Picture from: eizoglobal

"Contrast" and "Peak Brightness" , we raised a mouth when talking about the luminescent material of the screen above. The so-called "contrast ratio" is actually the "light and dark expressiveness" of the screen. The common expression is xxxx:1, such as 2000000:1. The larger the previous value, the higher the contrast.

Higher contrast means you can see more dark and bright details on this screen. For example, the following two pictures are typical contrast test pictures. The better the contrast of the screen, the clearer the squares behind it can be seen. If the contrast is not high enough, it may be pitch black or pale.

▲ White test. Picture from: glennmessersmith

▲ Black test. Picture from: glennmessersmith

So what does " peak brightness " mean? It refers to how bright the screen can be under extreme conditions, the unit is nit (nit). It should be noted that, like the 1500nit peak brightness of Xiaomi 11 and the 1200nit peak brightness of iPhone 12 Pro Max, they refer to the peak brightness of the entire screen, not the entire screen.

It is also necessary to understand that the peak brightness is equivalent to a 100-meter sprint and will not be maintained for a long time. In addition, there are more activation conditions. The higher the value, the more helpful it is to restore HDR scenes.

This has to mention " high dynamic range ". Mi 11 supports HDR10+ dynamic range, while all iPhone 12 series support Dolby Vision video playback and HDR display.

▲ The top is Mi 11, which can only open "HDR Color Vision" at the highest; the bottom is iPhone 12 Pro Max, which supports "Dolby Vision"

Earlier we had an article dedicated to introducing what Dolby Vision is and its advantages over HDR10 and HDR10+. To put it simply, Dolby Vision is the HDR video standard with the highest requirements for parameter indicators on the market, and requires a significant license fee. HDR10+ is an open specification and the current mainstream choice.

The main impact of this on ordinary users is the experience of watching videos. Some platforms such as iQiyi and Tencent Video already support videos in Dolby Vision format. When watching such videos, the iPhone 12 Pro Max experience will take a step forward.

▲ Below is the effect of turning on "Dolby Vision" for iPhone 12 Pro Max, with richer picture levels

The " refresh rate " and " touch sampling rate " to be discussed below are no strangers to everyone. The mainstream smartphone screen refresh rates are 60Hz, 90Hz, and 120Hz, which can be understood as how many frames of screen the mobile phone screen can display in one second.

The larger the number, the smoother the visual experience in dynamic pictures, especially when sliding pages. Of course, the price is that the screen power consumption is greater, and the battery life of the phone will be affected.

The current more advanced solution is to use an LTPO (Low Temperature Polycrystalline Oxide) panel to implement several levels of variable refresh rate on hardware, or to set several levels of variable refresh rate through software optimization. However, the hardware of Mi 11 does not support LTPO, and you can only choose 60Hz or 120Hz in the settings; iPhone 12 Pro Max only supports 60Hz.

▲ Mi 11 screen refresh rate options

The " touch sampling rate " is the number of times the screen can perceive your finger movement in one second. The higher the value, the more sensitive and responsive the screen will be. For game lovers, especially audio game lovers, this value is more important.

In the publicity column of Xiaomi Mi 11, " 8192-level dimming " is also an important parameter, which we have seen on OnePlus 8T. Compared with "4096-level dimming", 8192 level means that the brightness adjustment of the screen has a richer range. Especially in the automatic brightness mode, the brightness change of the mobile phone screen will be more delicate and smooth.

But this is only analyzed in theory. In fact, the brightness change of the screen has a great relationship with the sensitivity of the mobile phone's light sensor and the optimization of the algorithm. The numbers are for reference only, the actual experience is not determined by them.

▲ Screen comparison between iPhone 12 Pro Max (left) and Xiaomi 11 (right)

The screen parameters frequently mentioned by mobile phone manufacturers include color gamut, color accuracy and color depth.

To put it simply, the color gamut refers to the range of colors that the screen can display. The current mainstream color gamut is P3 and sRGB. For example, the default settings of iPhone 12 Pro Max and the adaptive mode of Xiaomi 11 are both P3 color gamut. Xiaomi also provides two other modes: sRGB color gamut in primary color mode, and NTSC color gamut in vivid mode.

At present, mainstream flagship phones have excellent coverage of color gamut. The data tested by WHYLAB shows that Mi 11 covers more than 100% of P3, NTSC, and sRGB color gamut. The iPhone 12's default P3 color gamut also exceeds 100%.

▲ The wider the color gamut, the richer the color. Picture from: viewsonic

Compared to color gamut, color accuracy may affect our perception more. Color accuracy refers to color accuracy. The "professional primary color screen" mentioned by Xiaomi Mi 11 means that this screen is very accurate in color restoration.

Xiaomi also gave specific values ​​on its official website: JNCD≈0.38; Delte E≈0.41. Although the relevant parameters of iPhone 12 Pro Max are not marked, according to the data of displaymate, the average color error is 0.9 JNCD, which is also a very good level.

Regarding the algorithms of JNCD and Delte E, we don't have to go into details, we just need to know that these two parameters refer to "the difference between the two colors that the human eye can perceive." The smaller the value behind, the better, indicating that the screen can restore the color more accurately.

▲Under P3 color gamut, iPhone 12 Pro Max (left) and Xiaomi 11 (right) have different color trends

Finally, let's look at the color depth . To put it simply, color depth refers to how many colors can be called under the same architecture, and the unit is expressed in bits. The larger the color depth, the better. For example, 8bit has more colors than 6bit, and 10bit is better than 8bit.

It can be understood as follows: From big red to deep red, the greater the color depth, the greater the number of transition colors between these two colors. When we look at photos and videos, we feel that the color transition of the screen is more natural.

▲ 10bit vs. 8bit color depth. Picture from: Jack Forest

Durability is the foundation of a good screen

In addition to the screen parameters frequently mentioned by the manufacturers above, the Mi 11 and iPhone 12 series also specifically emphasized the glass material.

Mi 11 uses Corning Gorilla's seventh-generation glass Victus . Corning said that this generation of glass has improved both drop resistance and scratch resistance. The drop resistance is 1.5 times that of the previous generation, and the scratch resistance is increased by 2 times.

In fact, this generation of glass named Victus first appeared in Samsung note 20 ultra. According to a test conducted by YouTube blogger Zack Nelson, the Samsung note 20 ultra's screen began to show scratches at level 6 Mohs hardness, and deeper grooves appeared at level 7 hardness.

▲Scratch resistance test of Note 20 ultra. Picture from: Zack Nelson

With the same glass of Xiaomi Mi 11, the anti-scratch performance should be equal to that of Samsung Note 20 ultra. However, the Xiaomi Mi 11 that we "run naked" already has some scratches. Friends who mind, it is best to put a layer of tempered film.

iPhone 12 uses a " super-ceramic crystal glass panel ." Apple said it has cooperated with Corning to combine nano-scale ceramic crystals and glass through a "dual ion exchange process." The hardness of nano-scale ceramic crystals is higher than that of most metals, so the hardness of super-ceramic panels greatly surpasses the previous glass panels, and the drop resistance is increased by 4 times.

▲ Propaganda slogan for iPhone 12 Pro Max

The dual ion exchange process also contributes to the scratch resistance and scratch resistance of the glass. However, with YouTube blogger Zack Nelson's "splendid hand", the iPhone 12 Pro's screen also began to show scratches at level 6 Mohs hardness, and the scratches deepened at level 7 hardness, which seemed to match Victus's performance.

▲ Anti-scratch ability test of iPhone 12 Pro Max. Picture from: Zack Nelson

For many users, whether the screen is durable may be more meaningful than pursuing parameters such as contrast and dimming level. After all, the cost of changing a screen is getting higher day by day, and wear resistance and drop resistance are king.

The new trend of mobile screen

Through the screens of the Mi 11 and iPhone 12 series, we can also speculate on the development direction of the flagship phone in 2021.

In terms of hardware, E4 will replace E3 luminescent materials and be applied to more flagship phones. This brings higher screen brightness and a better outdoor experience. The screen resolution will be 2K as the benchmark. If the flagship phone still uses a 1080P screen, there is a high probability that people will complain.

In 2020, the refresh rate of the screen has become a competitive selling point for flagship phones. And this year may pay more attention to the promotion of touch sampling rate.

The automatic adjustment of screen brightness may also become the next strength. Earlier when we mentioned automatic brightness, we would praise the iPhone's screen. However, with the attention of Android manufacturers, iPhone's achievements in this area will usher in more challenges.

The screen is getting better and better, and the maintenance cost is getting higher and higher. Changing the screen can cost one to two thousand at every turn, which makes consumers expect the durability of the screen to be enhanced. And Corning Gorilla's seventh-generation glass Victus may be one of the best solutions for the current Android camp.

And slogans such as Xiaomi Mi 11 "Professional Primary Color Screen" also let us see the flagship machine's efforts in "color accuracy". In the past, we took photos of different brands of mobile phones, or the same brand but different devices, there will be visible differences, mainly reflected in the difference in color.

▲ The look and feel difference between iPhone 12 Pro Max (left) and Xiaomi 11 (right) under default settings

This is not only because of the difference in screen hardware quality, but also because of the absence of the color management system .

Currently only Apple has a relatively complete color management system. As early as 1993 on System 7.1 Mac, the "ColorSync" technology has been applied. Starting early and paying attention, created the uniformity of Apple's device colors.

In the Android camp, OPPO is also about to apply the "full-link color management system" for the first time on the Find X3 series, which is also Android's first full-link color management system.

It can be expected that the screen of the flagship machine will be in full swing in 2021. And if you have mastered the meaning of the above parameters, you can happily "eat melons and watch the show."

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