How to avoid the LED display water ripple
Oct 19, 2018
When using the mobile phone or the camera to take the LED display, water ripples and scan lines appear on the photo, which makes the customer worry about the quality of the LED screen. In fact, these phenomena are not caused by the LED display itself. They are caused by the angle and focal length when taking pictures with mobile phones and cameras. You can understand this after reading this article.
"Water ripple" scientific name "Moiré effect"
When shooting a scene with a digital camera, if there is a dense texture, there are often inexplicable water-like stripes.
Simply put, moiré is a manifestation of the principle of beat. 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.
Moiré process
1. Two strips with slightly different spatial frequencies have the same black line at the left end. Because of the different spacing, the lines gradually overlap to the right.
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.
The display produces a moiré phenomenon
Method of eliminating moiré
1. Change the camera angle. Since the camera's angle to the object can cause moiré, slightly changing the angle of the camera (by rotating the camera) can eliminate or alter any moiré present.
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 and help eliminate the moiré.
4. Change the lens focal length. Different lens or focal length settings can be used to change or eliminate moiré.
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, with software processing. Eliminate any moiré that appears on the final image, such as Nikon Capture or Photoshop plug-ins.
