What is the refresh rate of a monitor screen and how does it affect perception

The refresh rate of the screen is one of the most controversial parameters of the monitor. Some argue that the higher it is, the better, and a low frequency reduces image quality and harms vision. Others are sure that a high frequency is for those who have nowhere to go for money, and that the eye still does not distinguish frequencies above 25 Hz. The truth, as always, is somewhere in the middle.

What is the refresh rate of the screen?
Regardless of what we see on the screen – a static picture or a dynamic video – the monitor constantly displays a series of images on the screen. It’s just that in the first case, all frames will be more or less the same, and in the second, the arrangement of details on the screen will change from frame to frame, creating the illusion of movement. The frame rate is the “screen refresh rate”.

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EX294 Practice Questions

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Just like in the movies, so many people remember the standard 24 frames per second for movies, i.e. 24 Hz. If no one in the theater complains about “low refresh rates,” so why do you need more on the monitor?

There is a persistent myth that 24 Hz is the maximum frequency perceived by the human eye. And that is why such a standard was chosen for cinema, and a higher frame rate simply does not make sense.

Dispelling this myth is very simple – just run some game on your computer that allows you to set the frame rate (FPS). It is better to choose a simpler game so that the video system confidently provides a high FPS. Try to set it first FPS 24 and observe, and then higher – for example, 50. In dynamic scenes, the difference will be obvious.

 

In movies, this is not so noticeable due to the fact that each frame of the film is shot with a certain shutter speed, so moving objects will be blurred. This softens the transition from frame to frame and additionally “convinces” our brain that the subject is moving.

 

By the way, many games have also learned to “blur” objects, providing smoother movement at low FPS. This effect is called motion blur. And the frame rate in cinema was chosen rather from economic indicators: lower frame rate – shorter film and simpler mechanics of a movie camera and projector. We needed a frequency that provides more or less smooth movement on the screen, but at the same time does not require large expenses. Why exactly 24? Because at this frequency, the film consumption per minute was exactly 30 yards, which simplified the calculation of the amount of film and, accordingly, the shooting budget.

60 Hz – Not enough or enough?
Another myth associated with screen refresh rates is harm to the eyes. They say that monitors with a low refresh rate flicker, which leads to eye fatigue and, in the long term, even diseases. It must be admitted that this is not entirely a myth – the flickering image is really harmful to the eyes. And monitors can actually flicker. But this has nothing to do with the refresh rate of the screen.

 

Previously, when all monitors were made on the basis of cathode ray tubes (CRT), the reason for the screen flickering was really the refresh rate. In a CRT, the phosphor on the screen glows only at the moment the electron beam “runs” through it. Therefore, the lower the “monitor frequency” was, the more noticeably the screen flickered. 60 Hz for such a monitor was completely insufficient.

However, the image on the LCD monitor does not blank out between frame refreshes. Yes, flickering is noticeable on some monitors, but not because of the screen refresh, but because of the backlight mode. In fact, in a static image, there is no difference between 60Hz and 200Hz monitors. If you are using a monitor for work, there is no need for high frequency. 60 Hz is sufficient.

A high frequency is not required even if you like to watch video on a monitor screen. Despite the fact that film is already history, the standard of 24 frames per second remains the main standard for video content. High-quality video is sometimes shot at 60 frames / sec, but high frame rates are rare. The reasons are roughly the same as a hundred years ago: the higher the frame rate, the larger the file size and the higher the requirements for the camera and the performance of the player’s processor. Therefore, there is no point in a monitor with a refresh rate greater than 60 Hz if you need it for watching movies. At least for now.

Who needs a high frequency?
In the paragraph about 24 frames, it was not for nothing that a computer game was mentioned. It is in fast-paced games that the influence of the refresh rate is most noticeable. But if you like to “drive to the tanks” after work, do not rush to the store for a 240-Hz monitor. First, decide if you really need a high refresh rate.

First, the refresh rate of the monitor must match the system’s performance. So first determine the maximum FPS in your favorite game – for example, using the Fraps utility . It is enough to download and run it – the current FPS will be displayed in the corner of the screen.

If your hardware can handle a maximum of 30-40 FPS, there is no point in a 100 Hz monitor. First, you will have to upgrade the system unit: change the video card , increase memory , and, possibly, replace the motherboard with the processor .
Secondly, refresh rate is not important in all games. The effect of changing the frequency will be noticeable only in dynamic games in which it is important to track fast moving objects – shooters, arcades, aircraft and racing simulators. If you are playing a top-down strategy or RPG, you are unlikely to notice any change at 100 hertz.

Third, keep in mind that high refresh rate monitors are more expensive than regular monitors. Therefore, if you are not an e-sportsman, think about it – for the price of a 144 Hz monitor by 21 “, you can buy a 27-inch monitor with a frequency of 60-75 Hz.

However, not everyone is able to take advantage of the increased refresh rate. Studies have shown that 13 ms is enough for the brain to recognize an image, but it can take dozens of times longer to properly respond to a received frame. Do not expect that by changing the monitor, you will immediately and many times improve your gaming performance.

Refresh rate and vertical sync
Another argument in favor of a high refresh rate is that it can eliminate the effect of the out of sync between the refresh rate and the FPS of the game. Since these numbers often do not match, it may happen that the game frame is redrawn when the screen is refreshed. As a result, the previous frame will be displayed on one half of the screen, and the next one on the other half.