Display Technologies of Xiaomi 12 Pro
The Xiaomi 12 Pro comes with a flagship 2K 120Hz screen, but strong parameters are not the whole story of the product, a good experience is more important. Today, Xiaomi introduced the two exclusive core technologies of Xiaomi 12 Pro: sliding variable speed screen and natural eye protection mode.
Android’s first sliding variable speed screen
Low-temperature polycrystalline oxide (LTPO) material allows the screen to actively reduce the refresh rate to save power when needed – a hardware capability, but also requires software cooperation – Xiaomi intelligent dynamic refresh rate technology. How to determine the most appropriate current refresh rate from the software layer?
Xiaomi uses three options for cross-judgment:
- List sliding speed
Ideally, the optimal refresh rate for a sliding list is to set “displacement/frame” as a constant, i.e., the farther the sliding distance, the more frames are needed.
In practice, to ensure no visual lag, the Xiaomi 12 Pro’s sliding variable speed screen raises the frame rate to 120Hz the moment the user’s finger touches the screen and then slows down the refresh rate in steps as the list sliding speed decreases until the list stops at 10Hz. Xiaomi 12 Pro is also the only model in the Android market with the sliding slowdown capability.
To achieve such a feature, we need to refactor the ScrollView and ListView of Android native controls to increase the ability to judge the sliding speed. In this process, Xiaomi needs to grasp the node of switching frame rate, if it intervenes too early, it will lead to visual lag; if it intervenes too late, it will not be able to save power.
- Intelligent judgment of scenes
After researching user behavior, Xiaomi knows that some scenes do not need a very high refresh rate, such as low frame rate animation, low frame rate video, and input method scenes. When the system detects these scenes, it can actively reduce the screen refresh rate to save power.
- Idle judgment
In browsing and reading scenarios, the screen is often stationary, so the device can reduce the refresh rate to 10Hz or even 1Hz to save power significantly.
Eye protection mode without color shift
Humans rely on daylight to regulate their biological clock, blue light with wavelengths between 415nm – 455nm will image melatonin secretion, to reduce the blue light emitted from the screen at night, cell phones are generally equipped with “eye protection mode” to reduce the amount of blue light.
The color of the screen is composed of RGB, when the blue light (B) component is reduced, the screen color is only red and green (RG), it will be overall yellowing, resulting in color distortion. The Xiaomi 12 series is equipped with a smarter screen eye protection mode, which no longer takes a “one-size-fits-all” approach, but makes different adjustments for different colors.
Take the CIE color space as an example, the color with the bluest light component is the area between pure blue (0,0,255) and pure white (255,255,255), while other colors also have blue light component, but the proportion is low.
Therefore, it needs to do different treatments for different colors to reduce most of the harmful blue light without affecting the hue of other colors. This is the natural eye protection mode of the Xiaomi 12 series.
On top of that, Xiaomi 12 series retains traditional features such as primary color screen, Dolby Vision, and 10,000-level dimming, and supports HDR video with a peak of over 1000nit, escorting flagship screen experience. “Hard strength determines the lower limit, soft strength determines the upper limit, this is the high-end flagship,” said Xiaomi.