How to eliminate the water ripple (moore pattern) on the LED display?

Date: 2019-11-18

• We often encounter customers who use their mobile phones or cameras to take a led display and find water ripples and scan lines on the photos, which makes customers worry about the quality of the led display. However, these phenomena are not caused by the LED display itself, but by the angle and focal length when shooting with a camera or mobile phone. Then let's spread the knowledge about water ripples (moore lines) today.
  

  There are often people who mistakenly think that the water ripple is the scan line, which is a big mistake.

  
  

  First, the difference between water ripple and scanning line phenomenon
  
  Water ripples generally exhibit a random arcuate diffusion state. The scan line is a horizontal black stripe line, mainly due to the lower display refresh rate, captured by the camera!
  
  

  Second, the "water ripple" scientific name "Moire effect" (Moireeffect)

  Shooting scenes with a digital camera, if there is a dense texture, there are often inexplicable water ripples. Simply put, moiré is a manifestation of the beat principle. Mathematically, an equal amplitude sine wave with two frequencies close to each other, the amplitude of the composite signal will vary according to the difference between the two frequencies.

  
  

  Third, the process of moiré generation

  1. Two strips with slightly different spatial frequencies have the same black line at the left end. Due to the different spacing, the lines to the right cannot overlap.
  
  2. The result of the overlap of the two stripes, the black line coincides on the left, so the white line can be seen. The right side is gradually misplaced, the white line is facing the black line, and the overlapping result becomes completely black. There are white lines and all black variations that make up the moiré.
  
  
  3. The two sets of stripes in Figure 2 are completely coincident, and the typical moiré can be seen.
  
  
  Fourth, the display produces a moiré phenomenon process
  
  As shown in the figure above: the led display is composed of rgb tri-color units, which are evenly distributed on the display.
  Note: If the pixel display density of the led display is just between the ccd distinguishable spaces, it is inevitable that the digital camera will still interpret some of the identifiable results, but it will also add an unrecognizable grayscale zone. The sum of the people will form a regular pattern, and the reaction is visually periodic ripples.
  
  Fifth，Methods for mitigating and eliminating moiré
  1. Change the focal length of the lens. Different lens or focal length settings can be used to change or eliminate moiré.
  2. Change the camera position. In addition, the moiré can be reduced by changing the angular relationship by moving left and right or up and down.
  3. Change the focus. Too sharp focus and high detail on the detailed pattern can lead to moiré, and a slight change in focus can change the sharpness, helping to eliminate moiré.
  4. Change the camera angle. Since the angle of the camera to the object causes a moiré, slightly changing the angle of the camera (by rotating the camera) can eliminate or alter any moiré present.
  5. Use the pre-mirror filter directly on the front of the ccd to make the exposure conditions meet the spatial frequency, thoroughly filter the high spatial frequency part of the image, and reduce the chance of moiré, but this will also reduce the sharpness of the image.
  6, the later processing with software. Use photoshop software, etc., to eliminate any moiré that appears on the final image.
  7, Jinghui intelligent photoelectric high refresh rate full color LED display can effectively reduce and eliminate moiré. Www.dmgled.cn
  

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