We’ve talked about the refresh rate (number of Hertz) of a TV before, but this much-discussed topic can cause a lot of confusion. The frame rate is also often referred to. But, what exactly is the difference between Frame rate vs refresh rate and what should you pay attention to when buying a TV?
We now know that the refresh rate of a TV is often a number that must be taken with a grain of salt because it can be measured in different ways and can also be interpreted. It is often a combination of techniques with which the number of Hertz of a TV is built up.
Frame rate vs refresh rate
Both terms / techniques are used interchangeably (even by us) and that is actually not correct. However, what they have in common is the use of frames. A video (film) consists of a large number of frames (still images) that together create a moving image. The number of frames that make up the incoming signal is the frame rate. For the Netherlands, for example, 25Hz / 50Hz is standard for TV channels and when you watch a Blu-ray movie, it is in many cases recorded at 24 frames per second.
The frame rate therefore has to do with the number of images per second of the source. The refresh rate is linked to the display that must display these images, in most cases a TV. The refresh rate indicates how many times per second the display refreshes the image (refresh), how many times per second the image is completely rebuilt. The refresh rate is indicated with Hertz (Hz). A TV with a refresh rate of 50Hz therefore displays each frame of a 25Hz signal twice per second.
The refresh rate is therefore something that the manufacturer of a TV can influence through various techniques. As indicated above, this often causes confusion and absurdly high refresh rates that are actually not very telling. However, many people think that the higher the refresh rate, the smoother the picture. However, this is only the case to a certain extent or clearly visible.
To be able to link the refresh rate of a TV to the frame rate of content, manufacturers of TVs must take this content into account. A TV with a 120Hz refresh rate can hardly display 50Hz content without advanced calculations that can affect the picture quality. In Europe, where 50Hz is the standard, TVs are also provided with a 50Hz, 100Hz, 200Hz, etc. refresh rate. With a 200Hz TV, each frame of a 50Hz signal is displayed four times per second.
Blu-ray 1080p / 24
However, with Blu-ray films with a frame rate of 24 frames per second, it is a different story. Most TVs nowadays support 24fps from Blu-ray, but how do you display that on a display of 50Hz or 100Hz? For this, the display is accelerated minimally, so that exactly 25 frames fit in a second. However, 25 frames per second could quickly cause flickering or shocking images and therefore this is often doubled to 50Hz. Each frame of the 24 frames will then be displayed twice per second and in total sped up slightly to fit. If your TV does not support 24fps, there is also software available (in the Blu-ray player) that converts the 24 frames per second to a number or is accepted by the TV.
Motion techniques and backlight scanning
Many TVs have Motion software with which you can boost the speed (the number of Hertz) by means of various techniques. However, this is all purely to give the feeling that images are displayed more smoothly. For example, some manufacturers use backlight scanning in addition to the refresh rate, which means that the backlight of the TV switches on and off 100 times per second. On a 100Hz display is then indicated as a total of 200Hz. There are also Motion options in the settings of TVs that allow you to make the playback smoother. For example, this combines elements of two frames that follow each other to make it appear smoother. However, the disadvantage of these techniques is that they can introduce the so-called soap opera effect (also called home video effect).
Frame rate vs refresh rate: Marketing
As you may gather from the above, manufacturers can influence a refresh rate in different ways, or have it influenced, and so many different numbers are used. Manufacturers also use their own terms to indicate the combination of different techniques, which only makes things more difficult for consumers. Although the refresh rate of a TV is an important part, you should not stare yourself blindly on this, especially because comparing is almost impossible when you only look at the numbers. It is therefore best to judge a TV on what you see and whether it meets your requirements. Incidentally, it must be said that the above applies to LCD / LED TVs and not plasma TVs.
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