When we are talking about TV picture quality, what are we talking about?

When we are buying a high-end TV, we often take "picture quality" as the first criterion to measure the quality of the TV.

But the picture quality of the TV is by no means clear just by looking at the screen parameters. It is not that you can draw conclusions by watching the promotional videos broadcast by the merchants in the mall.

For example, some time ago, a friend of mine bought a 4K TV with good parameters and went home, but he always felt that it was not high-definition enough for daily viewing. He complained that "it seems to have bought a fake 4K". In fact, he did not buy fakes, but because the quality of the picture presented to us on TV will be affected by many factors.

So how do you evaluate the "picture quality" of a TV? What factors determine the picture quality of a TV? We recently participated in a Sony TV technology exchange meeting to try to explore the answers to these questions.

▲ There are huge differences in picture quality between brands and models. Picture from: rtings

Screen quality is the basis of picture quality

The screen quality is to the TV what the engine is to the car. No matter how luxurious the car's interior is, the engine will pull the hips, which will fundamentally affect the driving experience.

The screen quality of a TV is mainly reflected by its panel material, resolution, color, contrast and other indicators. One of the most perceptible is the resolution .

Similar to a camera, with the same lens, a 48-megapixel camera, the picture must be more delicate than the 24 million-pixel camera. There is no doubt that in the case of the same size and the same source, the higher the resolution of the TV, the finer the picture displayed, and the theoretical look and feel will be better.

▲ Merchants often mark the resolution in the most prominent position. Picture from: AO

In recent years, the color TV market has shifted from 2K (1080P) to 4K (2160P). In 2018, mainstream products in the market have basically been equipped with 4K as standard. However, 8K TVs are in the ascendant when 4K is not yet fully popularized. Several first-tier color TV manufacturers, such as Sony, Samsung, Hisense, and Skyworth, all released 8K TV products at almost the same time.

From the data point of view, the resolution of 8K TV is 7680×4320, and 4K is 3840×2160. This means that the resolution of 8K is 4 times that of 4K . Of course, the price of 8K TV is also several times that of 4K TV.

▲ 8K TV can present amazing clarity

Even if Changhong, Samsung and other manufacturers have launched "entry-level" small-size 8K TVs, the price is "close to the people", but many friends are still confused: whether it is necessary to choose an 8K TV, low-end 8K and high-end 4K should be How to choose .

Sony used its own high-end 4K TV X9500H at the scene, which is an entry-level 8K TV of the same size as the competing product, and compared movies with the same content but different resolutions. We found that in terms of overall perception, clarity is not the most obvious difference between the two. The most intuitive difference is in color, contrast, and viewing angle .

▲ Sony 4K TV X9500H (left) vs. entry-level 8K TV (right)

On the whole, I prefer the look and feel of Sony’s 4K TV. The clarity can already show animal hair well, and the colors are more realistic. Combining the fact that the current 8K resources are very few and the file size is large and it is difficult to download, I think the answer to the above question is relatively clear. The current high-end 4K may be more practical than the low-end 8K .

▲Sony 4K TV X9500H (left) vs competing entry-level 8K TV (right)

Of course, if the budget is sufficient, high-end 8K can also be considered for purchase, especially for gamers . Sony used its own high-end 8K TV Z8H on site, and partnered with RTX3080 to run the "Death Stranding" game. In the resolution of 4K and 8K, it can be clearly seen that the text under the 8K screen is sharper and clearer.

▲ Enlarged screenshots of photos taken on the screen, 4K screen on the left and 8K screen on the right

So if two TVs have the same resolution and the definition of the static picture is the same, will the picture quality be different? The answer is obviously there. The differences that are most easily observed by our naked eyes are color, contrast, brightness and so on.

Color is a more subjective indicator. Everyone has different preferences for color, but the same thing is that we can tell which TV has richer colors and more natural colors. This involves professional terms such as color gamut and color depth.

▲ The same 4K OLED flagship TV, the color performance of the two is different

Among them, color gamut is a method of encoding colors, and also refers to the sum of colors that can be produced by a technical system. Wide Color Gamut (Wide Color Gamut) is very important for TVs that support HDR, which means a wider range of colors visible to our naked eyes. Generally, the color gamut of high-end TVs is much higher than that of low-end TVs.

The color depth is a parameter of the panel. Each time the color bit increases by 1 bit, the number of colors becomes 8 times the original. The current high-end TVs have been equipped with 10bit panels as standard, and even come to 12bit. And low-end TVs still generally use 8bit panels, and the color transition is slightly inferior.

▲Sony A9G with 10bit color depth

Contrast is simply the ratio of the brightest part to the darkest part on the same frame of image. In theory, high contrast can restore the scene more realistically, especially for bright and dark scenes.

When it comes to contrast, I have to mention the two concepts of peak brightness and black level . If the peak brightness is high, the picture quality in the highlight area will be better. Black level can be understood as the "depth of black", which is how thorough the black is. At present, OLED TVs have a huge advantage in contrast. The “self-luminous” screen can realize pixel-level light control, and the light source in the black area can be turned off to achieve pure black.

▲ OLED has great advantages in displaying black scenes

Sony compared its own A9G with a competing 4K TV on the spot. The peak brightness can reach more than 800, which belongs to the first echelon level.

▲ Peak brightness of Sony A9G (left) and competing flagship OLED TV (right)

Sony compares the Z8H with a more expensive 8K TV from a competitor. It can be seen that the difference in contrast between the two is still visible to the naked eye, and the Z8H has a stronger sense of three-dimensionality. In the high-light picture, the Z8H's detail retention is also better.

▲ Sony Z8H on the left; TV with the same specifications on the right

Compared with TVs, most people may be more aware of the new technologies carried by mobile phones, such as fast charging, and 120Hz high screen refresh. In fact, the color TV industry has been chasing the wave of new technologies. The 120Hz refresh rate is one of them, and the refresh rate actually affects the TV picture quality.

In the color TV market in 2020, high-end TVs equipped with 120Hz refresh rate panels are not uncommon, while TVs supporting 4K 120FPS HDR input are relatively rare.

▲ HDMI 2.1 interface can realize 4K 120p high quality input

For gamers, the higher the FPS, the smoother the game screen. With the ultra-high-definition resolution, you can get a great picture quality experience, and the sense of presence and immersion will be stronger. Sony has released four TVs with HDMI 2.1 interfaces, all of which support 4K 120FPS HDR input.

We experienced "Death Stranding " running at 4K 120FPS HDR on the spot. Compared with the 4K 30FPS game screen next to it, the game experience under high refresh rate has a qualitative leap. Even if the characters are running and spinning, the surrounding environment can clear and distinct.

▲ High-quality input also has certain requirements for the performance of the host

The chip determines the upper limit of picture quality

Glory product general manager Xiong Junmin once said, "The quality of a TV is not only determined by the screen, the chip also plays a vital role." This sentence is very pertinent, the screen determines the basis of picture quality, and the chip determines the upper limit of picture quality .

This is why the display effect of the same film source and the same parameter screen will be different between different brands and different models.

▲ Both use LG's top 4K OLED panel, but the color tends to be different

The chip suppliers for mainstream TVs mainly include MediaTek, Huawei HiSilicon, and Jingchen. For example, Sony’s mid- to high-end TVs use self-developed X1 series image processing chips (only responsible for image quality processing); Samsung QLED TVs use self-developed and self-produced AI quantum dot processors; TCL TVs mainly use Mstar and Amlogic chips; most Xiaomi TVs use Amlogic chips; Huawei smart screens use self-developed Honghu chips.

Each TV manufacturer has a unique tuning of the chip, which makes the picture displayed by the TV have great differences. Among them, the chip capabilities that affect image quality include image quality enhancement technology, dynamic compensation technology, color management, dynamic contrast enhancement, and zone light control.

▲ X1 series chips of Sony TV

A 4K TV with great panel parameters, I bought it home but found that the picture quality was not as good as I expected. This is most likely because it was "cheated" by the store's promotional video. After all, the quality of the promotional videos on the TV is very high and can "feed" the parameters of the panel.

And the movies we watch daily at home, most likely to be 2K or lower. "True 4K" content on streaming media is also relatively small, and if you download it, files of dozens of gigabytes are also tiring. This will test whether the TV chip can optimize these low-quality movies to the best picture quality .

In this regard, Sony’s X1 advanced and flagship chips, combined with the Xunrui image processing engine, can often optimize 2K video to a level close to 4K, and optimize 2K and 4K video to close to 8K, which is greatly improved To improve our perception of picture quality.

▲ Sony A8H equipped with X1 flagship chip can be optimized to close to ultra-high definition when playing 720P video

In terms of dynamic compensation technology, high-end TV models such as Sony, Samsung, LG, Mi Master, and Honor Smart Screen are basically equipped with MEMC functions , which means motion estimation and motion compensation. Most of the movies we usually watch have an original frame rate of 24FPS, and TV programs are generally 25FPS. TVs equipped with MEMC function will automatically add frames to a higher frame rate. With a high refresh rate panel, it will look extraordinarily silky. slip.

In addition to the quality of the panel, the color performance of a TV is also an important factor. Sony compared A9G with competing flagship 4K TVs on the spot. The panel quality of both TVs is top-notch. In the same image mode, you can see that the two have different inclination in color. It's more vivid and looks more pleasing at first glance, but Sony wins with reality in terms of durability.

▲ Sony A9G on the left, and a competing flagship 4K TV on the right

Skin color is the best way to show the difference in TV color toning. The display of skin color is different between each brand and model. This is very subjective. Everyone has different aesthetics. It is best to go to the store to watch before buying a TV. You can even download the movies you watch daily to a USB flash drive and take it to play the test.

▲Sony Z8H (left) and competing 8K TV (right), the skin color of the characters is very different

But for most people, the more realistic the color reproduction, the more comfortable it will look. The same is true for directors and colorists. They also want the audience to see the true colors they see in front of the monitor.

Fortunately, the current first-tier manufacturers are working hard in this direction. The "user mode" or "movie mode" in the color mode of each brand TV is generally an attempt to restore the original author's intention . Sony also demonstrated the Aurora Calibration Mode launched in cooperation with Tencent Video at the scene. It automatically sets the corresponding parameters of the TV through the cooperation of software and hardware. While improving the quality of online content, it can greatly improve the problem of color deviation.

▲ Cloud Audiovisual Aurora Calibration Mode

With regard to technologies such as dynamic contrast enhancement and zone light control , it is also a project that cannot only look at the parameters, but still needs to "see is believable."

▲ Partition light control display of high-end LED TV

Besides the screen and chip, what else can we talk about?

As a 4K TV user, I very much hope that the TV can display the picture quality it should have. Unfortunately, the 4K resources on the Internet are very "bloated". A 4K movie is about 50GB in size. It takes a long time to download, and problems such as "resource errors" may occur during the download process.

So I very much hope that the "Universal" will be able to launch more high-quality 4K content for online viewing. On this user's pain point, Sony also introduced how they did it on the spot. That is to cooperate with content platforms such as Tencent and Wasu to launch high-quality video resources for Sony users.

In Tencent Video, Sony users can exclusively enjoy the " IMAX Enhanced " zone, which contains popular videos for playback. Using its proprietary image enhancement technology and DTS audio technology, the picture details are more refined and the sound effects are more immersive. In its Dolby Vision mode, you can enjoy the industry's highest HDR film standard, which are Sony's advantages in content.

▲ Right is the exclusive "IMAX Enhanced" resource for Sony TV

When reviewing the past advertising campaigns in the color TV industry, we can find that most manufacturers are instilling the concept of " buying a TV is buying a screen ", so many consumers have gradually formed the concept of "a good screen, good picture quality", thinking similar to " The slogan "equipped with imported LCD panels" means that the picture quality of the TV must be good.

Only in recent years, some manufacturers have begun to promote the importance of chips, especially high-end TVs. This is a good sign. After all , the combination of high-quality panels and powerful algorithms can only enter our homes with high image quality , rather than staying in the promotional videos in the mall.

Regrettably, there are still many vendors who avoid the content side. The scarcity of high-quality content is actually a big pain point for users. We look forward to more manufacturers paying attention to the construction of the content side in the future, so that consumers can enjoy more high-quality film and television sources online.

Tell simple and easy-to-read stories. Work email: wanghelong@ifanr.com.

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