When led displays are used in control rooms, TV studios and other places, moire sometimes occurs. This article will introduce the causes and solutions of moire.
LED displays have gradually become the mainstream display equipment in control rooms and TV studios. However, during use, it will be found that when the camera lens is aimed at the led display, occasionally there will be stripes like water waves and strange colors (as shown in Figure 1), which is often referred to as the Moire pattern.
Figure 1
How do moire patterns come about?
When two patterns with spatial frequencies overlap, another new pattern is usually created, which is usually called moire (as shown in Figure 2).
Figure 2
The traditional LED display is composed of independent light-emitting pixels, and there are obvious non-light-emitting areas between the pixels. At the same time, the photosensitive elements of digital cameras also have obvious weak photosensitive areas when they are sensitive. Moire was born when digital display and digital photography co-existed.
How to eliminate or reduce Moire?
Since the interaction between the grid structure of the LED display screen and the grid structure of the camera CCD forms a Moire, changing the relative value and grid structure of the grid structure of the camera CCD and the grid structure of the LED display screen can theoretically eliminate or reduce Moire.
How to change the grid structure of camera CCD and LED display?
In the process of recording images on film, there are no regularly distributed pixels, so there is no fixed spatial frequency and no moire.
Therefore, the moire phenomenon is a problem brought about by the digitalization of TV cameras. To eliminate moire, the resolution of the LED display image captured in the lens should be much smaller than the spatial frequency of the photosensitive element. When this condition is satisfied, it is impossible for stripes similar to the photosensitive element to appear in the image, and there will be no moire.
In order to reduce moire, some digital cameras are equipped with a low-pass filter to filter out higher spatial frequency parts in the image, but this will reduce the sharpness of the image. Some digital cameras use sensors with higher spatial frequencies.
How to change the relative value of the grid structure of the camera CCD and the LED display screen?
1. Change the camera angle. Moire can be eliminated or reduced by rotating the camera and slightly changing the angle of the camera.
2. Change the camera shooting position. Moire can be eliminated or reduced by moving the camera side to side or up and down.
3. Change the focus setting on the camera. Too sharp focus and high detail on detailed patterns can cause moire, and changing the focus setting slightly can change the sharpness and help eliminate moire.
4. Change the focal length of the lens. Different lens or focal length settings can be used to eliminate or reduce moire.
Post time: Nov-15-2022