What is “state of the art” in TV resolution today may become yesterday's technology tomorrow. Within a few years, the resolution standards came into their own: HD ready was followed by Full HD, Full HD was replaced by 4K, and with 8K the next standard is already moving into the living room.
Regardless of this, these abbreviations keep causing confusion. The difference between UHD and 4K, in particular, raises questions, as many assume that this is the same standard - but this is not (entirely) correct. Let’s start from the beginning.
What is screen resolution, anyway?
The resolution of an image is usually specified in terms of the number of horizontal and vertical pixels, i.e. the number of pixels on a screen. HD ready means, for example, that an image has a resolution of 1,280 pixels on the horizontal axis and 720 pixels on the vertical axis.
Pixels are building blocks of an image, which - equipped with a corresponding color value - create the overall picture like tesserae.
It should be noted that the pixel information alone only provides limited information about how sharp the image on a screen actually is for the human eye. Rather, the resolution should be set in relation to the size of the screen. Only then does the density of the pixels on a screen emerge.
The pixel density is specified in the unit PPI (pixels per inch). For example, Full HD achieves a significantly higher pixel density on a 32-inch television than on a 40-inch device: the display is therefore finer.
What is 4K?
4K televisions get their name from their resolution, which is around 4,000 pixels wide. Usually it is 3,840 x 2,160 pixels. This resolution is also known as Ultra High Definition (UHD). It is the direct successor to Full HDTV and, with over eight million pixels, has four times as many as its predecessor. TV sets with UHD resolution have an aspect ratio of 16: 9.
The term 4K originally comes from the cinema sector, where a resolution of 4,096 x 2,160 pixels is used. The aspect ratio of 4K is originally 17: 9, with some pixels being cut away for the 21: 9 cinema format. However, 4K and Ultra HD are largely used synonymously today.
Bonus: 4K resolution provides razor-sharp images
The quadrupling of the resolution from Full-HD-capable to UHD represents a significant improvement for the picture quality. Due to the higher number of pixels, television pictures can be displayed in even more detail and the pictures become significantly sharper. This makes them look even more realistic. In addition, the individual pixels are much smaller for the same screen size.
On a 55-inch HD television, one pixel is around one millimeter wide, and on a 4K television, it is only half that. As a result, the television picture is still clear and clear even with a smaller distance between the viewer and the screen. The individual pixels cannot be seen.
Large 4K televisions are therefore more suitable for small living rooms. The distance can be reduced to two meters, which allows the viewer to immerse himself more intensely in the action.
Disadvantages of a 4K TV: It consumes more power and when the seat is wide, the difference to Full HD is hardly noticeable.
UHD and 4K explained in technical terms
UHD: The abbreviation UHD stands for "Ultra High Definition". This is the successor standard to Full HD. The resolution of UHD is 3,840 x 2,160 pixels (= 8,294,400 pixels in total) and is thus four times as high as that of its predecessor, Full HD.
4K: The term 4K comes from cinema technology and is now also used colloquially for televisions - although this is technically not entirely correct. 4K refers to the horizontal resolution of 4,096 pixels (4K = 4 kilos, i.e. four thousand). The number of vertically arranged pixels in televisions is 2,160 pixels (2K). This is why one sometimes comes across the designation 4K2K.
Strictly speaking, a UHD television does not achieve the resolution of a 4K device because the number of horizontal pixels is lower. In practice, however, the terms UHD and 4K are used almost synonymously. This is why many televisions “only” have a resolution of 3,840 x 2,160 pixels, even though they are designated as 4K devices.
Other important abbreviations for screen resolutions:
8K: 8K stands for 7,680 x 4,320 pixels. In the meantime, some devices with this resolution are already on the market. For them, however, you sometimes have to dig deep into your pocket. Manufacturers such as Samsung and LG are pioneers here.
Full HD: The Full HD standard offers a resolution of 1,920 x 1,080 pixels. You will usually find this resolution in movies from Blu-ray Discs. Real 4K resolution, on the other hand, is only offered by Ultra HD Blu-rays.
HD ready: The HD-ready resolution of 1,280 x 720 pixels has almost disappeared from televisions - even smaller new devices usually support at least Full HD. The HD-ready standard is mainly encountered today when receiving high-resolution television programs.
4K resolution doesn’t fit all TV programs so far
Of course, the picture that 4K televisions display also depends on the program they are receiving. Most TV channels now broadcast in full HD quality. 4K TVs cannot reach their full potential with this signal. However, the devices extrapolate the image to its resolution. They do not show more details, but the picture on them is better than HDTV sets. It looks cleaner and clearer.
Some broadcasters are already broadcasting productions in Ultra HD. Streaming providers such as Netflix or Amazon Prime are also increasingly offering series and feature films with the appropriate resolution for 4K TVs.
Conclusion: the difference between UHD and 4K is hardly relevant
- The common standards for screen resolution are HD ready, Full HD, UHD, and 4K.
- Today, UHD and 4K are often used synonymously as the successor to Full HD.
- The term 4K originally comes from cinema technology and describes a resolution of 4,096 horizontal pixels.
- The UHD resolution of most televisions, on the other hand, is “only” 3840 x 2160 pixels.
- There are now the first TV sets that already have a resolution of 8K. However, these are not (yet) affordable for everyone.