I believe many people have had this experience, that is, when shooting full-color LED displays at work, irregular water ripples appear on the LED display screen, which are physically called "moir é patterns".

Moir é pattern is a high-frequency interference that occurs in the photosensitive components of digital cameras or scanners, causing color high-frequency stripes in images. Simply put, moir é pattern is a manifestation of the principle of differential photography. Mathematically speaking, when two sine waves with similar frequencies are superimposed, the amplitude of the synthesized signal will vary according to the difference between the two frequencies. Due to the irregularity of the Moir é pattern, there is no clear shape regularity.

 

This phenomenon may occur in both images captured with advanced digital cameras and scanned images. This phenomenon can occur when the intricate patterns on an object, such as woven patterns on fabrics or parallel lines very close to a building, overlap with the patterns on imaging elements. If two patterns overlap, it usually produces another new pattern.

When we take photos with a camera, sometimes in addition to moir é patterns, we also see scanning lines. So what is the difference between moir é patterns and scanning lines?

 

The difference between water ripple and scanning line phenomenon

1. Water ripple: generally presents an irregular arc-shaped diffusion state!

2. Scanning line: Horizontal black striped straight lines, mainly due to the low refresh rate of LED display products being captured and presented by the camera!

 

The process of generating moir é patterns

1. Two stripes with slightly different spatial frequencies have the same black line position on the left end. Due to the different intervals, the stripes gradually move to the right and cannot overlap.

2. Two stripes overlap, and on the left side, a white line can be seen due to the black line overlapping. And the right side gradually shifts, with the white line facing the black line, resulting in a completely black overlap. There are white lines and full black variations, forming a moir é pattern.

 

The process of moir é phenomenon in full-color LED display screens

The pixel distribution density of a full-color LED display screen is exactly within the range that CCD can distinguish. It is inevitable that digital cameras will still interpret some recognizable results, but also add unrecognizable grayscale areas. The sum of the two will form regular patterns, which are visually reflected as periodic ripples.