Xiaomi Mi 10 Flicker Sensor
Today Xiaomi phone on weibo published a detailed article about strobes. Which explains uses of Xiaomi Mi 10 Flicker Sensor in day to day life and also explained why annoying strobes come when taking pictures and how to eliminate it.
Why are there always annoying strobes when taking pictures?
I believe that everyone has encountered the following awkward scenes when taking photos with mobile phones:
- Scene 1: During a meeting, there is an important PPT content on the projector. I want to record it with my mobile phone and find that there are some stripes on how to shoot.
- Scene 2: When there is a class in school, the teacher’s courseware always has a lot of points. I want to use my mobile phone to take down the PPT courseware, but I find that the photos have a lot of stripes blocking the key content;
- Scene 3: On the way home at night, there are rows of yellow street lights in the heavy snow, and I am going to take out my mobile phone to record the beauty of this moment. When I open the photo, I find stripes in the picture. At this time, my mood is not so good.
These stripes not only affect the picture effect, some even block the content we are going to shoot, and it is difficult to remove even after the use.
Where do these stripes come from? Why can Xiaomi 10 better “avoid” these stripes? This starts with the strobe phenomenon.
What is a strobe?
Strobe streaking is when we observe the screen of another electrical appliance from the screen of the mobile phone. In the shooting picture of the mobile phone, there will be a bright line from the bottom of the screen to the top, and it will appear from the bottom of the screen.
Why do strobes occur?
There are two conditions to produce strobe fringes:
- l AC light sources: such as those from televisions, computer screens, and home appliances. Our national household electrical standard is 220V 50Hz, the fluctuation of light intensity is 100Hz, and the period is 10ms. If you use a mobile phone to take photos indoors, the light source emitted by the indoor TV or computer screen is like a wave, and their energy is changing every moment.
- l Electronic rolling shutter exposure: As the name suggests, the electronic rolling shutter is realized by controlling the chip progressively. It does not have a shutter in the actual sense, but controls the sensor by energizing it, making different parts of it sensitive to light at different times. Degrees are different, and exposure is performed line by line until all pixels are exposed.
At this time, if we are using an “electronic rolling exposure camera”, we shoot with a shorter exposure time. Because the exposure time of each line is different, the energy obtained may also be different; then the light energy received on different photosensitive surfaces is different, which results in stroboscopic streaks on the image.
How to eliminate pesky strobes?
Now that we understand the cause of streaks, we can “remedy the situation” by detecting the frequency of the light source, obtaining the period of the light source, and then calculating the exposure time of the camera, thereby completely eliminating the occurrence of streaks.
Why do ordinary mobile phones have a strobe phenomenon?
They lack effective light source detection hardware. Traditional anti-flicker is based on screen content detection. The disadvantages are:
- l Only support 50/60Hz detection, can not adapt to AC power frequency in different countries;
- l Low detection accuracy and easy calculation error.
How can Xiaomi 10 completely eliminate strobes?
In order to eliminate flicker more accurately, Xiaomi Mi 10 independently uses a flicker sensor, which is a sensor that samples ambient light.
Xiaomi Mi 10 Flicker Sensor’s unique features are:
- Higher detection accuracy : It is more suitable for the camera’s anti-flicker setting to automatic, accurate detection of 50/60Hz power, convenient for countries to travel and roam.
- Wider detection range : In addition to 50/60Hz AC power, 60/90Hz display, even theoretically 1 ~ 500Hz light source can detect.
- More detection uses : By identifying artificial light sources and frequencies, using a custom exposure strategy, while suppressing stroboscopic streaks, it does not affect the exposure of other scenes.
Knowing the frequency of the light source knows the period. We can adjust the exposure time to be an integer multiple of the light source detection period to “synchronize” the exposure speed with the light source.
Now we turn on the camera of Xiaomi Mi 10 Pro, click “Settings”-“Anti-flicker”-“Auto”, the anti-flicker function will take effect.
I took another shot of the streaks, and the “strobe streaks” completely disappeared.
Let’s look at the comparison chart before and after the switch is anti-flicker: