After a short period of one month, we once again met the technology leader who had released “Serious†at Sony BRAVIA headquarters in Tokyo, Japan. Although the focus of this exchange still revolves around the Z9D, which has been hailed by many as "the strongest black technology TV on the surface," but after further communication with Mr. Ogura, many R&D backgrounds on the Z9D and more domestic consumption. Unprecedented technical details gradually surfaced ... It is precisely these details that make people have a new experience of "We know everything about TV!"
Toshiyuki (Toshi) Ogura) Resume:
In 1983 joined the Sony TV Division, responsible for TV image technology research and development; at the end of 1997 went to Sony America, responsible for the R & D of the TV machine; in 2004 returned to Japan to continue to engage in TV R & D. In 2007, he was transferred to the Digital Imaging Business Division, responsible for the camera and camcorder technology strategy, and served as the head of the Hardware community. Since 2012, he has entered the reorganized HE&S Division and is responsible for Sony's television technology strategy. He has been involved almost exclusively with the development of Sony's major television sets since the 1980s.
Our exchange must begin with HDR. Because HDR has become the most popular technology in the color TV industry in 2016, most of the domestic professional media's understanding of HDR still remains in how much a certain TV can reach. nits brightness is the level of good HDR TV. What is the reality? What?
About HDR Technology
When mentioning HDR, one has to mention the concept of "transfer function".
Whether shooting, taking pictures, or displaying, the "transfer function" is used. It can be divided into EOTF Electro-Optical Transfer Function and OETF Optical-Electro Transfer Function. TV imaging is a typical EOTF, which converts electrical signals to optical signals. Shooting video is the process of converting OETF light into electricity.
There are two kinds of HDR conversion functions that are currently common in the industry. One is ST2084 (the Association of Film and Television Engineers)-led Perceptual Quantizer technology, and the other is the Hybrid Log-Gamma (ITU-led). HLG) technology. The main differences between these two technologies are as follows:
ST2084/PQ is currently used by the famous Dolby company in the movie industry. This technology is based on the EOTF transfer function (focusing on the camera side) and defines a maximum brightness of 10,000 cd/m2. Its characteristic is that the defined maximum brightness exceeds the limits that today's TV panels can reach. The brightness of the TV screen is below the maximum brightness of the panel, and for parts exceeding the maximum brightness of the panel, the information of the screen will be lost. Therefore, it is relatively more suitable for film and documentary applications.
The HLG was praised by the BBC/NHK TV industry's big coffee, because it is based on the OETF transfer function (focusing on the imaging side) and does not define the maximum brightness value, but can be achieved due to the erelative (relative) relationship. 1200% brightness dynamic range. Therefore, HLG allows the device to display a wider contrast, and the signal will not be lost when there is a signal higher than the highest brightness of the panel. It is more suitable for most occasions such as live video broadcast.
After talking about the transfer function of HDR, look at several mainstream HDR technologies in the industry today. Dolby Vision, HDR10, HLG, and Prime/SL-HDR1 from Dolby, respectively.
Both Dolby Vision and HDR10 follow ST2084/PQ, so the two specifications are basically the same. The Prime/SL-HDR1 focuses more on the transmission standard and can also temporarily ignore it. The main comparison still depends on the HLG.
Koichiro Ogura said that the biggest difference between HLG and Dolby Vision compared to HDR10 is that HLG is a relative system, while Dolby Vision and HDR10 are absolute (absolute) systems. The former uses the relative value to represent the change in brightness, while the latter uses the absolute value to indicate the brightness.
For example, if the maximum brightness of a TV is lower than the upper limit of ST2084, the luminance signal in the HDR content cannot be completely reproduced (but it is not completely lost because it uses a display mapping method). The details and contrast will be lost. In the relative system of HLG, since the brightness changes are all relative values, an accurate brightness contrast relationship can be achieved in the OETF portion captured by the camera. HLG-based TVs, even if they have different maximum brightness display capabilities, can adapt themselves to relative values ​​and accurately reflect changes and contrasts in the brightness of each part.
In addition, HLG can also support standard SDR TVs (that is, a large number of non-HDR TVs currently on the market), and it is also a free technical standard. In contrast, HDR10 is also free, but it cannot be compatible with SDR TVs, not to mention the need for additional codecs and the Dolby Vision specification for licensing fees.
Sony's current approach is to support HLG (4K HDR on BRAIVA). However, as a rational and objective engineer, Ogura Sumiyoshi has not completely denied the advantages of Dolby Vision and HDR10. He is still very appreciative of the advantages and disadvantages of these types of technology streams. He stated that which technology he chooses is based on his own. The characteristics of the product, as well as the quality of the picture you wish to bring to the user, are determined.
Although we have used as much text as possible, this part of the knowledge is still very professional. As long as the average user knows, Sony's HDR technology does not excessively pursue the absolute value of a certain data, but more in line with the imaging principle of television, but also better at reproducing the details of the picture and comparison, which is enough.
"Accuracy" is the essence of Sony's image quality
In fact, every time Sony launches a new TV set, it will organize a very special "small dark house" link. There will usually be a few TV sets with different brands, and the actual quality of the television sets will be compared. Compared with the previous time at home, this experience session at the “Little Dark House†at the headquarters has given us more benefits (still unable to take pictures) thanks to a better hardware and software environment.
This time, there were 6 sets of television sets in the small darkroom section, including 2 Sony’s own Z9D, 1 Taiwan’s flagship X9300D this year, 1 OLED TV of a competition company, and 1 flagship quantum dot HDR of a competition company. TV. In addition, there is a radio and television professional-grade R/G/B OLED monitor BVM-X300 with a value of more than RMB 300,000 to be used as a reference for the quality performance of these televisions.
Let me talk about the black level performance first.
It is generally believed that due to the self-illumination principle of the OLED TV, its black level performance can be perfectly described.
However, Koichiro Otake said that there is a big difference in the display mode between the OLED TVs currently on the market and the RGB OLED monitors used as reference objects. At present, civil-level OLED TVs only use white light OLEDs as light sources, and they still need color filters; in order to compensate for the problem of insufficient brightness, white sub-pixels are added, which makes it difficult to adjust the white balance. So currently on the market OLED TVs are difficult to do a good color reproduction accuracy, especially when displaying darker images, the color shift problem will be more serious (in contrast to professional-grade RGB OLED monitors are RGB three primary colors A sub-pixel emits light independently and does not require a color filter, so white balance is well controlled).
Another problem is related to "Gradation". Although the current OLED technology can be very deep in black, but it is still unable to achieve accurate Gradation (gradient), which leads to some relatively dark scenes in the TV At that time, it was impossible to achieve a precise gradient of blackness.
For example, the above image is also a black-and-white photo. Because the right side has a better (gradient) ability, the grayscale is more abundant, the details and information that can be seen in the image are larger, and the image level and details on the left are relative. A lot less,.
Sony engineers set up a very rich and slightly changing grayscale image signal to be reproduced on these devices. The professional X300 OLED monitor is undoubtedly the most perfect performance. The black-to-white transition in the center of the screen is like a cream in the mouth. The Z9D is not as exquisite as the X300. However, what is surprising is that there is absolutely no presence of any color levels, but the softness of the spread varies; the flagship LCD of the other competition company is gray and whitish, and the color scale is extremely rough (Each There is a width of 1-2 fingers between a color scale, and the performance of the OLED is most eye-popping: the portion occupying about 30% of the center of the screen is completely dead black, without any transition and hierarchy, and the grayish part of the edge appears. Obvious color cast, not to mention the coarse color effect between the two.
This is the Gradation performance of civil-grade OLEDs. Some of them are appalling. However, the Z9D's display effect cannot be shot with a normal camera, so there is no photo display
The Z9D's high level of closeness to professional-grade monitor grayscale display capabilities, in addition to the new 14-bit smooth fade feature in the X1 Extreme engine, has a significant relationship with the backlight system.
Compared with ordinary TVs, the Z9D's biggest feature is the use of a backlight system called BacklightMaster Drive. Compared with conventional direct-lit LED backlight technology, this system uses a high-density matrix backlight. Second, each LED can be independently controlled. The third is to prevent light interference between individual LED particles through a special structure. .
How effective is this set of backlighting system? In fact, Ogura Ogura had a brief presentation at the Z9D conference. At the time, a Z9D engineering machine removed the LCD panel layer. The audience only watched the backlight and they could see that there was a Black and white images with clear outlines and details!
Therefore, Z9D can use a powerful backlight system to achieve accurate backlight brightness control, combined with liquid crystal layer through the control of liquid crystal deflection of the light, and ultimately achieved a very close to professional-grade RGB OLED monitor "Gradation (gradient)" performance; The civilian-level OLEDs can only adjust the brightness of the final image through the white light OLEDs on the bottom layer of the panel. No matter whether the precision or the brightness level is far apart, it is not difficult to understand the poor grayscale performance.
It may be questioned that televisions need to display rich picture colors. It is not really worthwhile to use “black-and-white†“Gradation†effect comparisons. In fact, this is a misunderstanding: Because grayscale gradient performance is an LCD TV image. One of the basic properties, if the TV can not reproduce accurate gray scale, then all the color performance will be affected.
Koicura said that Sony has designed televisions that are highly close to professional monitors, not to show off, so they will not announce how many LED particles the Z9D uses, and how much peak brightness it can achieve (these are other color TVs. Manufacturers commonly used hanging window means). Sony has always believed that a good picture quality must be able to accurately reproduce the state of the video signal itself (which can also be understood as accurately recreating the lens language that the video creator portrayed), rather than simply highlighting how beautiful the color is, and how strong the contrast is.
In the video quality comparison test of the video clips, his views have also been continuously verified: whether it is a CG cartoon or a film shot by a 4K HD movie camera, the Z9D's color style, contrast between light and darkness, and the X300 are all 30. The multi-million-dollar professional monitors are highly similar, while the civilian-level OLED TVs seem to have a high saturation and brighter colors, but a typical exaggerated style is very different from the picture the director tries to express on the monitor ( If it's not a comparison of the X300 professional monitor, we may have a hard time understanding what the exact colors and shades are.
Z9D will become an epoch-making product in the history of LCD TVs
After more than ten years of development, LCD TVs have matured in technology and industry chain. The average enterprise researches and develops a new product, the shortest as long as one month time. However, Ogura Minzhi stated that Z9D's R&D has already started as early as three years ago. For a LCD TV, this R&D cycle can be quite long.
Objectively speaking, Sony TV is much better than it is today in the era of CRT. In 2004, flat-panel TVs are about to usher in the popular time slot. Sony has introduced a CRT player "HR36" that has kept many audio-visual enthusiasts in mind so far. When asked if the Z9D had a similar status to the HR36 of the year, the old Sony's answer was a bit surprising: he did not think how legendary the HR36 was. On the contrary, the Z9D was more like an LCD TV. Important product.
Because HR36 is Sony's last flagship CRT TV, but it does not use too much innovation in itself, all kinds of technologies are highly mature, may be just because it is the last CRT's sake will make people forget. From an engineer's perspective, the lack of technological innovation is the biggest problem. Although the Z9D was born in the highly mature and perfect time period of LCD technology, both the backlight system and the picture quality engine system have adopted a large number of innovative technologies. Not only the picture quality has reached the highest value of LCD technology, but even the professional level. The distance between RGB OLED monitors is also at your fingertips.
This is where he dares to say "We know everything about TV!"
In fact, in the last 2 to 3 years, with the arrival of a large number of Internet brands in the domestic color TV industry, there is no lack of rhetoric similar to “revolution, subversion†in our ears. The traditional color TV companies are also often labeled as “conservative, profitable...†and it seems that they have become the enemy of consumers overnight.
However, through this exchange, Sony is considered to be a brand representative of traditional color TV companies. The technical strength and attitude of product development demonstrated by us must be respected. After all, China's Internet TV companies, which are still willing to spend three years developing a TV set realistically, and collectively in an impetuous position, are not the only ones missing this spirit of craftsmanship?
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