LED display eliminate or reduce moiré
When the LED display screen is used in the control room, TV studio and other places, it will sometimes cause moiré interference to the camera screen. This article introduces the causes and solutions of moiré, focusing on how to choose an LED display to reduce or eliminate moiré.
LED displays have gradually become the mainstream display equipment in control rooms and TV studios. However, in the long-term use process, it will be found that when the camera lens is aimed at the LED display, occasionally there will be stripes and strange colors like water waves, which is often referred to as the moiré phenomenon.
How does moiré come about?
When two patterns with spatial frequencies overlap, another new pattern is usually created, which is usually called moiré.
The traditional LED display is composed of independent light-emitting pixels, and there are obvious non-light-emitting black areas between the pixels. At the same time, the photosensitive elements of digital cameras also have obvious weak photosensitive areas when they are sensitive.
Since the CCD (image sensor) target surface (photosensitive surface) of the camera is similar to the image in the middle, and the traditional LED display is similar to the image on the left, it is composed of dot-matrix light-emitting tubes arranged in a consistent manner. A grid-like pattern is formed, and the two overlap to form a similar moiré pattern.
How to eliminate or lighten moiré?
Since the interaction between the grid structure of the LED display screen and the grid structure of the camera CCD forms the moire pattern, 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 the moire pattern. Moiré.
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 moiré.
Therefore, the moiré phenomenon is a problem brought about by the digitization of TV cameras. To eliminate the moiré, 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 moiré.
In some digital cameras, in order to reduce moiré, a low-pass filter is installed 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. Moiré can be eliminated or reduced by rotating the camera and slightly changing the angle of the camera.
2. Change the camera shooting position. Moiré 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 moiré, and changing the focus setting slightly can change the sharpness, which in turn helps eliminate moiré.
4. Change the focal length of the lens. Different lens or focal length settings can be used to eliminate or reduce moiré.
The LED display screen is composed of independent light-emitting pixels, and there is an obvious non-light-emitting black area between the pixels. Find a way to turn the non-light-emitting black area into a light-emitting area, and reduce the brightness difference with the independent light-emitting pixels, which can naturally reduce or even eliminate the moiré.
Is there a way for the LED display to turn the non-luminous black area into a lighted area?
LED display with COB packaging process, it is easy to do this. If we have the opportunity to put COB’s LED display and SMD’s LED display together, we can easily find that: COB’s LED display emits softly like a surface light source, while SMD’s LED display clearly feels that the luminous particles are one by one. Independent glow point. As can be seen from Figure 3, the sealing method of COB package is significantly different from that of SMD. The sealing method of the COB package is the overall light-emitting surface of many light-emitting pixels. The sealing method of the SMD package is a single light-emitting pixel, which is an independent light-emitting point.
Summary: How to eliminate or reduce the moiré pattern of LED display?
1. Adjust the camera shooting angle, position, focus setting and lens focal length.
2. Use a traditional film camera, a digital camera with a higher spatial frequency sensor, or a digital camera with a low-pass filter.
3. Select the LED display screen in COB package form.
