With the development of science and technology, 4K TV has gradually spread to thousands of households from the "cutting-edge technology" that will be chosen by niche enthusiasts.
The delicate picture quality and more shocking viewing effect have made it the object of attention of many users, and some users who have requirements for TV picture quality will also have the idea of "non-4K not buying" when choosing.
However, if Xiao Hei wants to tell the friends that the 4K TV you bought happily may not be exactly 4K, I don't know what kind of ideas the little friends will have?
What kind of TV counts as a 4K TV?
In the previous article "The same 1080P video, why is the gap so large?" In it, Xiao Hei mentioned the definition of 4K in the field of video and television. Here, Xiao Hei will re-introduce it to everyone.
The so-called 4K, if simply calculated according to the standard of 2K, should refer to a video or playback device with a horizontal resolution (that is, a longer edge resolution) of 4096 pixels.
However, this standard was adopted by the Digital Cinema Initiatives and is generally only used in professional fields. In the field of home monitors and televisions, the horizontal resolution is basically 3840 pixels.
▲This picture should be able to see very clearly
In this way, we can calculate that there are about 8.29 million pixels in a 4K TV. This number is quite important, and friends should remember it before reading the following.
In addition, unlike the concept of pixels in photography, in a display device, a pixel is composed of multiple monochrome pixels, which are called "subpixels". Taking traditional televisions and displays as an example, a pixel will contain three sub-pixels of red, green and blue, and these three colors are the three primary colors in optics.
▲ Common display devices, one pixel contains three subpixels
There is one more point of knowledge. In the case of the same screen size, the more effective pixels, the better the display effect, and we will also use this knowledge point below.
Through the above small knowledge points, we can draw such a conclusion: in general, the screen resolution can reach 3840×2160 TVs, with 8 million pixels, can be regarded as 4K TVs.
The same is a 4K TV, why is the display effect different?
Xiao Hei just made a simple definition for 4K TV, but this definition is not rigorous.
As an example, we can see that some small partners on the Internet will ask such a question: "Why is the 4K TV I bought not as good as I imagined?" ”
Why does a good-looking 4K TV not achieve the desired clarity? On the one hand, some supporting hardware, such as TV boxes do not support 4K, or the film source itself is not 4K, the perception of people will definitely be affected. On this point, Xiao Hei also explained in the previous article, and will not be repeated here.
On the other hand, the TV itself.
In general, the pixel arrangement of TV screens is mostly the traditional RGB tri-color arrangement. The knowledge of RGB arrangement, Xiao Black has also been popular many times in previous articles about screen display and photography.
In the field of television, the pixel arrangement of different panels is also different, such as the "row station" or staggered arrangement of the VA panel, the "arrow-like" arrangement of the IPS panel, and so on.
▲ The "row station" of the general VA panel pixels is very suitable for the preferences of obsessive-compulsive disorder
Although the design of these pixel arrangements is different, they are all designed to better play the characteristics of the panel. Most of the 2K and 4K screens under general cognition also use such pixel arrangements.
Around 2014, LG Display introduced the use of RGBW four-pixel 4K panels to the market, and TVs using such panels also attracted many consumers at a more affordable price. But then came a big debate about whether RGBW's 4K panels were 4K or not.
Xiao Hei has no intention of judging who is right and who is wrong, at least through the authoritative body ICDM (International Committee for Display Metrology) and other relevant certification bodies at home and abroad, the RGBW arrangement of 4K panels is really 4K.
But there is no doubt that there is a big difference between a panel that uses RGB tri-color pixels and an RGBW panel.
From the number of subpixels contained in a single pixel, Samsung's RGBW scheme "Green UHD" contains two subpixels per pixel, that is, red-green or blue-white. LG's RGBW scheme "G+ HUD" is a pixel with 2.5 subpixels.
Both Samsung and LG Display have launched RGBW panels
In terms of actual use experience, the biggest advantage of the traditional RGB tri-color pixel panel is the number of effective pixels.
The white pixels in the RGBW panel do not participate in the display of colors, but only participate in the control of display brightness.
Therefore, in the actual number of effective pixels for displaying color, the RGBW panel is 25% less than the RGB panel. The above mentioned a key data, that is, the total number of pixels in 4K TVs is about 8 million, and on this basis, minus 25%, it is the effective pixels of 4K TVs with RGBW panels, about 6 million.
Obviously, other things being equal, there will be a gap in the clarity of a 4K TV with an RGBW panel. Although the difference between the two is almost imperceptible to the naked eye when watching daily, there is still a big difference for users who have extreme requirements for TV clarity.
▲ Samsung official production of the spit video
In the spit video officially produced by Samsung, it was complained that LG Display's RGBW scheme was actually a "3K panel".
Another difference is the color displayed on the TV.
Whether it is color purity or accuracy, RGBW panels have a more obvious gap with traditional RGB panels.
▲ The same spit video from Samsung
As can be clearly seen in the above figure, under the same lens, the actual imaging effect of the 4K TV of the RGB panel is purer than that of the 4K TV of the RGBW panel, and the level of color is more obvious.
So, is the RGBW panel useless? The answer is obviously no, because if so, then it is also impossible to be brought to market.
The first advantage of the RGBW panel is, instead, determined by white pixels that do not participate in the color display. Since white pixels are mainly used to adjust the brightness of the picture, the power consumption of the RGBW panel will be much lower than that of the RGB panel when displaying the same brightness screen. In other words, the screen brightness of the RGBW panel will be brighter than the RGB panel under the same power consumption.
On the other hand, due to the advantages in terms of light transmittance, the cost of RGBW panels is also slightly lower than that of RGB panels, which makes RGBW panels play a very important role in the popularity of 4K TVs.
In short, the RGBW panel 4K TV price is low, but also save power, while the traditional RGB panel TV actually looks and feels better, small partners can buy on demand.
Some extra trivia
Just now, Xiaohei introduced two different pixel arrangement panel schemes of 4K TV and compared the advantages and disadvantages between them.
There were still three little pieces of knowledge left, and Xiao Hei felt the need to mention it briefly.
The first little knowledge is how to see the panel scheme used by the display device we are using.
This is actually very simple, with the mobile phone we use at hand, which has better camera performance.
▲ Little black computer monitor
Turn on the camera on your phone and switch to the telephoto camera, then take a photo as close as possible to the white picture displayed on the monitor.
In order to focus accurately, small partners can open Word and type a few words, and then shoot at the nearest distance of the phone's telephoto camera, which can be accurately focused, and then zoom in.
The picture above is the pixel arrangement of Xiaohei's self-use computer monitor taken by Xiaomi Mi 10S, and you can clearly see the red, green and blue pixel arrangement from left to right. Zoom in a little more on this image and it looks like this:
Are the colors very bright?
The second trivia is related to another four-color pixel panel. In addition to the RGBW panel, there is also a WRGB panel, which represents the manufacturer still LG.
In the picture above, it is the real shooting of an OLED panel TV of LG. It can be seen that although it is also composed of subpixels of red, green, blue and white, unlike the RGBW panel, the WRGB panel contains four subpixels of red, green, blue and white in a single pixel. This ensures that while increasing brightness and energy consumption, there is still delicate picture quality and accurate colors.
But in this way, its production costs have also been greatly improved, so WRGB panels are currently only appearing on some high-end TVs.
The third trivia is about 4K projectors.
▲ A certain Sony 4K projector
Nowadays, projectors are increasingly popular with young people. It can be placed and adjusted at will, the display area is basically unlimited, and it is easy to carry, so that it can solve various pain points of young people.
Now, the advent of 4K projectors has greatly improved the previously criticized projection clarity problem.
But there are also differences between 4K projectors. In some projectors, in order to achieve a display effect close to 4K, manufacturers add "4K enhancement technology" to projectors with native pixel values of about 2 million or 4 million, so that they can achieve better display results.
▲The display chip of the projector
Although the original effect of the projector imaging depends on the display chip used, under the blessing of "4K enhancement technology", it is indeed possible to bring the actual imaging effect of the projector to improve, as long as the actual imaging pixels reach 8.29 million pixels, we can think of it as a 4K projector.
There are also a few small partners also need to pay attention to: there are also some 4K projectors on the market that the actual imaging effect is less than 8 million pixels, and it must be consulted when purchasing. In addition, 4K projectors using 4K enhancement technology generally achieve display performance improvement by moving pixels quickly, so even in the most ideal environment, the actual display effect is still not clear enough.
Of course, there are not many projectors that can achieve 4K projection at the chip level, and the Sony projector in the previous picture is.
However, its information can only be found on the official website of Sony professional products, and it cannot be purchased directly on the official website.
As for the price... 79999 yuan, Xiao Hei said that he could buy two of the most expensive TVs on Sony's official website, and even had one dollar left to buy lollipops to eat.
Image source: original pictures, Sony official website, Samsung official website, Baidu search