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- What is ‘water ripple’? What’s the difference between high and low refresh rate?
What is ‘water ripple’ of LED Display? What’s the difference between high and low refresh rate?
Content
- What is refresh rate?
- Visual perception of the human eye
- Latency rate of high refresh rate screens
- Capturing motion footage
- What is stroboscopic effect?
- Visible stroboscopic effect
- Stroboscopic effect
- Conclusion
What are those ‘water ripple’ patterns on the LED display? Their scientific name is “Moiré patterns.” When photographing objects with a digital camera, intricate textures often produce inexplicable water-like stripes, these are Moiré patterns. Simply put, Moiré patterns are a manifestation of the principle of interference.
1. What is refresh rate?
When we were children, we all watched animated movies. In fact, it is the effect of high-speed playback of many pictures. One action is divided into many actions, each action is a frame, and there is a progressive relationship between each frame. When these pictures are played at high speed, due to the visual residual of the human eye, they will feel that these pictures are integrated.
The more frames an animation is split into, the finer the detail becomes. The faster the rate at which each frame transitions, the smoother the visual continuity. Refresh rate refers to the scanning speed of these frames, so a faster scanning speed results in a more stable image. The unit of measurement for this speed is Hz (Hertz). Hz is the unit of frequency in the International System of Units (SI), representing the number of periodic cycles per second. A higher number indicates a higher refresh rate.
2. Visual perception of the human eye.
In fact, for motion scenes, a high refresh rate only delivers noticeable clarity when synchronized with a high frame rate.
The effect of a 24-frame movie on a 60Hz screen in the above picture — even slowing it down doesn’t help.
The image above shows the effect of a 120Hz LED screen displaying a 120fps movie. Slowing down the footage makes the effect even more noticeable.
3. Latency rate of high refresh rate LED displays.
A 60Hz LED display has a response time of 16.67ms. For a 120Hz screen, it’s 1000ms ÷ 60Hz, which is approximately 8.33ms, a 50% reduction.
Above is a delay map of the mouse’s movement trajectory, with the advantage being smoother screen performance. Simultaneously, swiping the screen yields the experience shown below, where motion blur is noticeably reduced. Slow-motion playback effect:
4. Capturing motion footage.
In theory, high refresh rate LED screens refresh more images per unit time than regular screens. Therefore, for motion images, more trajectory images of object movement can be observed.
5. What is stroboscopic effect?
LED displays create images by refreshing the screen through the lighting and extinguishing of LED lights. As LED lights illuminate and extinguish row by row, each row of light-emitting diodes alternates repeatedly between a lit state and a dark state. At lower frequencies, this rapid switching between light and dark becomes clearly perceptible to the naked eye, causing the screen to appear to flicker abnormally. This phenomenon is known as flicker. While flicker is an inherent characteristic of LED display operation, flicker at different frequencies can cause varying degrees of harm to the human eye!
6. Visible stroboscopic effect.
The human eye is an extremely complex system with significant individual variation. The vast majority of people can detect light flickering below 80Hz, at which frequency the eye clearly perceives changes in brightness. Flicker frequencies below 80Hz are also referred to as visible flicker. Visible flicker is unacceptable in both general lighting and display applications.
7. Stroboscopic effect.
For flicker frequencies above 80Hz, the human eye is less likely to perceive it, yet it significantly impacts spatial perception. For instance, moving objects may appear as a series of static images—the flicker effect. Due to this phenomenon, people may experience illusions, perceiving rapidly operating equipment as moving slowly or even stationary, creating a highly hazardous situation.
A high refresh ≥3840Hz rate perfectly aligns with the human eye’s tolerance range while substantially enhancing frame transition stability. It boosts dynamic visual effects, delivers smooth playback without stuttering or flickering, effectively prevents eye strain, minimizes motion blur during high-frame-rate video playback, reduces water ripple effects when filming with phones or cameras, and produces crisp, detailed imagery with vivid, highly accurate colors.
7. Conclusion.
In summary, high refresh rate LED screens do deliver a more comfortable viewing experience for the eyes in specific scenarios, with the reduction in screen flicker being particularly noticeable.
Of course, higher quality comes with higher costs, so clients should also consider their actual needs when making a choice to purchase an LED display.
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