We all like to take pictures when we see something beautiful, but when you take a picture of an LED screen with your cell phone, you may get some ripples. Many people who don’t know much about LED displays will think it’s the poor quality of LED displays, but it’s not. This article will tell you why this happens and what you can do about it.
1. Moire effect
- The principle ofthe Moire effect
The Moire effect, with digital products on the LED display, when shooting, some irregular ripples are the Moire effect. This phenomenon can not be seen by the naked eye because it is a visual perception, a superposition generated, that needs to be observed through a third-party perspective can be observed.
Just like, when you open the window to see the scenery outside, it is very clear, but when you look through the screen window to see the scenery outside, you will find patterns like water waves.
This is because when you look through the screen window, the viewing angle and spacing provided by the screen window are different from when you look at it yourself, so this phenomenon occurs. The reason for water ripples appearing on LED display screens through digital products is similar. However, another factor is frequency, as the display frequency of digital products and LED displays can also cause this situation.
- The process of generating the Moire effect
Water ripples are caused by the overlapping of two different spatial frequencies. As shown in the figure below:
At first glance, the black lines look the same, but the more you look to the right, the more asymmetrical the lines become. These two black lines represent the spatial frequencies of digital products and LED displays, and we will find that they are increasingly out of sync.
When you put these two black lines together, you can see a lot of overlap, overlapping produces shadows, and non-overlapping produces white lines. This happens when you shoot an LED screen with a digital device and two spatial frequencies overlap. There is a black line and a white line, and the spatial frequency is not uniform, resulting in the Moire effect
At the beginning of the overlap of the two black lines have not completely overlapped, there will be a slight ripple phenomenon. After a while, when the two black lines completely overlap, a typical resulting Moire effect will appear.
This is the whole process of the Moire effect.
2. What are the effects of the Moire effect
Moire effect is invisible to the naked eye; it must pass digital products to be able to see, so this will affect the digital products for the LED screen shooting.
For example, at concerts or places where people might use digital photography, if you can’t get rid of the ripples well, then the photos and videos they take will be very ugly because they shoot when the LED display and digital products respond to the phenomenon of Moire effect in photos and videos affect the aesthetic.
3.Method to eliminate the Moire effect phenomenon
After reading the content above, we know that the Moire effect has a great influence on taking photos and videos, and eliminating water ripples is crucial; here are ways to eliminate the Moire effect. Let’s take a look
- In terms of camera equipment
1). Changing the angle and position of the camera: As we said above, Moire effects occur in part because of viewing angles and positions, so changing the angle of the camera, some Moire effects can be eliminated by rotating the camera, and some Moire effects can also be eliminated by moving the camera up and down.
2). Change of focus: Both the phone and the camera will have a focus when shooting, changing the sharpness of that focus and the resolution of the entire picture; adjusting the resolution of the camera and the LED display to a similar resolution can also remove the Moire effect.
3). Change shutter speed: Shutter speed is to the photo refresh rate; shutter speed, the photo refresh rate is high; shutter speed is low, the photo refresh rate is low. Lower the shutter speed, reduce the refresh rate, and help ease the LED display brought by the Moire effect phenomenon.
4). Use Filters: Filters are very common filter lens props; the filter directly installed in front of the lens can effectively filter out some unnecessary light, make its exposure conditions meet the spatial frequency, achieve the same frequency lens and LED display, and reduce the occurrence of Moire effect phenomenon.
- Post-processing aspect
If you’ve done all of the above and still can’t avoid some of the Moire effects, then there is a final method, and that is post-image processing. Today’s photo editing software is very developed; they are simple and fast in operation, such as Photoshop; through editing, they can eliminate the Moire effect in photos.
For many photography enthusiasts of the LED display, the Moire effect is a pain, but it is not a screen or phone problem. This point is also clearly explained in the article.
Under the current technical conditions, many LED displays have high refresh rates. Due to their extremely high refresh rates, some of the Moire effect phenomena can be well avoided from the LED display itself, but the price will be higher; we can choose according to our budget.
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