When customers use their mobile phones or cameras to take LED displays, they often find water ripples and scanning lines on the photos, which makes customers worried about the quality of LED displays. 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. Let’s popularize the knowledge of water ripple (molar pattern) today.
1. Difference between water ripple and scanning line phenomenon
People often mistakenly think that the water ripple is the scanning line, which is a big mistake.
Water ripple generally presents an irregular arc diffusion state. The scanning line is a horizontal black stripe line, which is mainly caused by the low refresh of the display screen and is captured and presented by the camera!
2. The scientific name of “water ripple” is “Moir é effect”
If there is a dense texture in the scene taken with a digital camera, inexplicable water wave like stripes often appear. In short, the moire pattern is a manifestation of the beat difference principle. Mathematically speaking, when two equal amplitude sine waves with similar frequencies are superimposed, the amplitude of the synthetic signal will change according to the difference between the two frequencies.
3. The process of molar striation
a. Two stripes with slightly different spatial frequencies have the same black line position at the left end. Due to the same spacing, the lines gradually to the right can coincide.
b. As a result of the overlapping of the two stripes, the white line can be seen on the left because the black line coincides. The right side is gradually misaligned, the white line faces the black line, and the overlapping result becomes completely black. There are white lines and all black changes, forming molar patterns.
c. When the two groups of stripes coincide completely, you can see the typical molar pattern.
4. Process of moire phenomenon on display screen
The LED display screen is composed of RGB three-color units, which are evenly distributed on the display screen.
Note: if the pixel distribution density of LED display screen is just between the intervals that can be distinguished by CCD, it is inevitable that the digital camera will still interpret some recognizable results, but it will also add unrecognizable gray-scale areas. The sum of the two will form regular lines, which is visually periodic ripples.