The Higher The Resolution, The Clearer? This Article Takes You To Reveal The Portrait Of Dongyu Zhou On The Screen Pixels Of Huawei P40

- Apr 10, 2020-

On March 26, Huawei held a global online conference and released three new Huawei P40 series products including Huawei P40, Huawei P40 Pro and Huawei P40 Pro +. P40 is equipped with a 6.1-inch, 2340x1080 resolution flat OLED screen, P40 Pro and P40 Pro + are equipped with 6.58-inch, 2640x1200 resolution four-curved OLED screen, the higher the resolution, the better the display effect? In addition, P40 series mobile phone pixel pixels There are many arrangements, such as BOE's "Zhou Dongyu" arrangement, LG's diamond arrangement and so on. Let's talk about the resolution and pixel arrangement of mobile phone screens.


1. Mobile phone resolution and PPI


Our mainstream mobile phone screen resolution is 1080P, and now there are many mobile phone resolutions up to 2K, which is the 2K screen that manufacturers say. The resolution of 1080P is actually 1920px * 1080px, which can be understood as 1920 pixels in the vertical direction of the mobile phone and 1080 pixels in the horizontal direction. Similarly, the number of pixels on a 2K screen is 2560px * 1440px. Generally speaking, the higher the resolution of the mobile phone screen of the same size, the clearer and more delicate the display effect of the screen. But with the same resolution screen, different screen sizes and resolutions are different. 40-inch 1080P resolution TV and 6-inch 1080P resolution mobile phone, 6-inch 1080P mobile phone resolution will be much better. Therefore, the resolution parameter is only comparable if the screen size is the same.


So, how do you compare clarity between screens of different sizes?


The display of the mobile phone screen is completed by extremely small color blocks. These small color blocks are called pixels. Simply speaking, the more pixels, the more clear and delicate the mobile phone screen display. Pixel density (PPI) can compare the sharpness of screens of different sizes. Pixel density (PPI) refers to the number of pixels on the diagonal of the screen per inch, so that the two variables of resolution and screen size are considered in the calculation process.


Therefore, mobile phone screens of different sizes have a unified indicator. The higher the PPI, the clearer and finer the mobile phone screen. This may be more accurate than looking at the resolution.


Apple ’s official website lists the PPI parameters after comparing the resolutions of various models. In this way, the clarity of each model can be explained more accurately.


But this is not far from all-because different materials, or even the same material comes from the screens of different manufacturers. Due to the different pixel arrangement, even if their PPI values are the same, there are still differences in the display effect.


2. Standard RGB arrangement


Each pixel of the display is actually composed of three sub-pixels of red, green and blue. such as:


This is the current mainstream liquid crystal display and the arrangement of pixels on the LCD mobile phone screen (such as the current iPhone 11). Because the cones of the human eye are most sensitive to the three colors of red, green, and blue, we can get different colors by adjusting the brightness of these three colors. This is also the "RGB three-color model" currently used in the screen industry.


The LCD panel emits light through the backlight module, and then passes through polarizing plates and alignment films to control the brightness of each color. In order to achieve the purpose of displaying different colors, the arrangement of sub-pixels and the principle of light emission of the standard RGB of the LCD panel have been developed for nearly two decades, and are very mature today.


3. The birth of OLED and the arrangement of PenTile


The OLED screen has the characteristics of no need of a backlight layer and a liquid crystal layer, and a single sub-pixel emits light. Therefore, the screen can be made lighter and thinner. In addition, the OLED screen is superior to the traditional LCD screen in terms of contrast, viewing angle, and maximum brightness. In recent years, with the development trend of mobile phone screens, OLED screens have become mainstream.


The advantages of OLED screens are very prominent, but there is an obvious disadvantage-short life. Early Samsung tried to use the standard RGB arrangement on the OLED screen (such as the well-known Note2), but it did not persist due to life problems (OLED screens from four to five years ago were particularly easy to burn).


So Samsung developed this sub-pixel arrangement called "PenTile".


We see that PenTile increases the blue and red areas (the number of pixels decreases accordingly), only the green pixels are completely retained, and the adjacent two pixels share a green pixel. Calculated, the total number of sub-pixels at the same resolution is reduced by about one third.


Green is in the middle of the visible spectrum and is the most sensitive color of the human eye. When the screen is displayed, the problem with green is the most easily noticed by the human eye. For the red and blue at the edge of the spectrum, the human eye is relatively less sensitive.


The blue pixels on the OLED screen are the most deadly. Because the luminous efficiency of blue pixels is much lower than that of red and green. Therefore, to make blue achieve the brightness of the other two colors, it is necessary to increase the current, which makes the blue pixels decay faster than other pixels, which affects the life and color accuracy of the entire screen. After increasing the light-emitting area of the blue pixel, the current through the blue pixel can be reduced while ensuring the relative brightness. Thereby increasing the screen life.


Although red pixels will not have this problem, the human eye is also not sensitive to it. For the sake of color balance and calibration, it also expanded its pixel area.


With this sub-pixel arrangement and the optimization of later software algorithms, the problem of short OLED screen life has been significantly improved in recent years. But this arrangement also has side effects: the most important issue is that the actual resolution is reduced. Although it is consistent with standard RGB in the number of pixels, after all, the effective sub-pixels are about one-third less. A 1080P resolution screen arranged by PenTile, the equivalent standard RGB PPI value is probably 720P, and the display effect is equivalent to the 720P resolution on the LCD screen.


In order to make up for the problem of reduced resolution, Samsung began to adopt a special sub-pixel arrangement. OLED screen sub-pixels are no longer in the traditional vertical column form, but are arranged in a diamond shape, so it is also called a diamond arrangement. In this way, the arrangement between the sub-pixels can be made closer, which makes up for the loss of resolution caused by the "PenTile arrangement" in a certain sense.


But even with the upgraded diamond arrangement, the actual resolution is only about 80% of standard RGB. The actual resolution of OLED screens is still lower than traditional LCD screens. This is why Samsung wants to use a 2K screen on its flagship model. The 2K resolution on the OLED screen is basically the display effect equivalent to the 1080P resolution on the LCD screen.


4. Delta and "Zhou Dongyu Arrangement"


Explain clearly "PenTile arrangement". The problem of "Zhou Dongyu Arrangement" is easy to explain. The general situation is this, because the PenTile arrangement and the diamond arrangement have been patented by Samsung. Therefore, domestic manufacturers must find another way to solve the problem of sub-pixel life. So there are two self-made arrangements:


One is the Delta arrangement


Another variant of Delta, the design is from BOE. Split a green pixel into two sub-pixels. It looks like a duck, which is kindly called "Zhou Dongyu Arrangement" by netizens.


At present, the principle of these two arrangements is the same as the PenTile arrangement: by extending the area of the blue and red sub-pixels to extend the life of the screen.


Of course, the arrangement of pixels on a screen is only the basis for the quality of a mobile phone screen. Also include specific software adjustment methods such as color gamut, color accuracy, etc. The same mobile phone screen, the final effect will vary from manufacturer to manufacturer.


In summary, through the above analysis, with the same screen size, the higher the resolution, the higher the clarity. The resolution of screens of different sizes is compared by pixel density (PPI). The higher the pixel density, the higher the resolution.