如果您在市场上购买新的高清电视，您可能已经注意到某些 4K 型号还具有称为HDR（高动态范围）的功能。
HDR是一种显着提高显示器亮度和对比度的技术。HDR客观上优于旧电视技术，但并非所有电视机都是平等的，HDR也不是一个单一的标准。尽管如此(Nonetheless)，HDR提供了最佳的电视体验，我们将解释原因。
最简单的部分：4K
该技术最容易理解的部分是“4K”位。这只是指电视的分辨率。在这种情况下， “分辨率(Resolution)”是指电视的像素数。大多数“4K”电视是UHD或“超高清(Definition)”，其分辨率略低于专业好莱坞(Hollywood)电影制作中使用的适当(proper 4)4K(K)标准。( standard)
超高清(UHD)电视的像素网格为 3840×2160 像素。这是FHD(FHD)（全高清(Full HD)）显示器中像素数量的惊人四倍。UHD分辨率根本与HDR无关。无论分辨率如何，显示器都可以提供HDR 。例如，1440p 电脑显示器和手机面板提供HDR，尽管分辨率低于 4K UHD。
(HDR)当涉及到电视时，您会发现HDR几乎完全与 4K 或更高分辨率配对。因此，这两个电视规格同时被提及也就不足为奇了。
什么是动态范围？
电视的动态范围本质上是屏幕可以达到多暗和多亮之间的距离。如果这听起来有点像对比度，那么您并没有完全错。
然而，动态范围更多的是关于在你得到“粉碎”的黑色和“爆裂”的白色之前，可以在图像的最暗和最亮的部分保留多少细节。
你可能还记得《权力的游戏》中臭名昭著的那一集(infamous episode of Game of Thrones)，场景如此黑暗，以至于许多观众只能看到一个糊状的黑色图像。该节目的创作者将动态范围推得太低，以至于低端电视(TVs)（大多数人都有）根本无法再现细节。
标准动态范围(Dynamic Range)与高动态范围(High Dynamic Range)
内容和显示的动态范围是标准化的，以便掌握视频内容的人知道他们可以工作的限制。SDR 或标清范围(Standard Definition Range )内容是由相机和显示技术的技术限制造成的。
现代相机和显示器可以捕捉和再现更广泛的明暗范围。不仅如此，它们还可以捕捉和再现图像中那些以前会丢失的黑暗和明亮部分的细节。
HDR所做(HDR)的只是扩大范围并增加相机捕获和屏幕可以显示的可用信息。如果您使用SDR相机制作内容，您不会在HDR屏幕上看到任何改进。同样(Likewise)，如果您将HDR内容放在SDR屏幕上，它看起来就像SDR内容。
HDR 标准
在撰写本文时，有五种HDR标准：HDR10、HDR10+、HLG、杜比视界(Dolby Vision)和Technicolor的高级 HDR(Advanced HDR)。
HDR10
支持最广泛的HDR标准是HDR10。几乎(Virtually)所有HDR显示器都支持HDR10，并且大多数HDR内容都在HDR10中可用。其他标准对HDR(HDR)的原始实现进行了改进，通常只有更便宜的设备才支持HDR。
HDR是由负责定义UHD分辨率标准的联盟UHD Alliance创建的一个相对简单的开放标准。要使电视符合HDR10标准，它必须满足特定的技术峰值亮度和对比度标准。
HDR元数据是有关在(metadata)HDR内容中编码的光照级别的附加信息，在HDR10的情况下是静态的。这意味着无论您正在观看的显示器或特定场景如何，指定的亮度和对比度级别都是相同的。这与使用动态元数据的HDR标准相反，后者在每个场景的基础上更改这些亮度和对比度值。(HDR)
HDR10+
UHD联盟(Alliance)没有定义HDR10+。相反，它是由全球最大的电视制造商之一三星定义的。(Samsung)
顾名思义，HDR10+建立在HDR10的基础之上。它通过添加动态元数据来实现这一点，这意味着HDR目标基于当前场景。三星(Samsung)让HDR10+成为开放标准，就像最初的HDR一样。因此，只要符合纸上要求，任何人都可以将此认证放在他们的电视上。
杜比视界 HDR
杜比视界(Dolby Vision)是重要的HDR标准之一，您会发现相当多的高端电视(TVs)和媒体设备支持它。例如，最新一代的Xbox游戏机支持杜比视界(Dolby Vision)。
杜比视界(Dolby Vision)认证比HDR10或HDR10+更具挑战性，因为它是一个许可标准。电视和其他HDR设备必须通过认证才能显示杜比视界(Dolby Vision)标签。
该标准使用动态元数据。这意味着图像会根据您的特定杜比认证HDR(HDR)电视的功能进行调整，该电视内置了制造商设置，有助于解释如何显示以杜比视界(Dolby Vision)控制的内容。
混合对数伽玛 (HLG)
混合对数伽玛的(Log-Gamma)工作方式与HDR10或杜比视界(Dolby Vision)不同。该标准没有元数据。相反，它使用计算来计算出HDR显示器上沿SDR伽马曲线的亮度级别。
该标准是为广播公司开发的，允许单个信号在SDR和HDR集上工作。然而，目前很少有 4K 电视支持HLG，因此除非有更高的采用水平，否则HLG的未来充满不确定性。
Technicolor 的高级 HDR
Technicolor 是任何对电影感兴趣的人都知道的名字。这家公司开创了电影行业的大部分显示技术。
(Advanced HDR)Technicolor的Advanced HDR试图将一些技术知识带入HDR中，但与(HDR)Dolby Vision和HDR 10相比，它是迄今为止最小的，因此它注定是一场艰苦的战斗。
更糟糕的是，Technicolor HDR系列中有三个标准：SL-HDR1、SL-HDR2和SL-HDR3。SL-HDR1向后兼容SDR，使其成为HLG等广播的可行选择。SL-HDR2具有动态元数据，是HDR10+和杜比视界(Dolby Vision)的竞争标准。SL-HDR3仍在开发中。
LG 是三星(Samsung)的主要竞争对手，它倾向于在其电视(TVs)中包含更广泛的受支持HDR标准，支持Technicolor，您还会看到以飞利浦(Philips)品牌销售的支持该标准的电视机。
HDR 影响色彩再现
虽然HDR主要是关于峰值亮度和暗度，但颜色也会受到影响。借助HDR(HDR)视频中嵌入的额外亮度数据，可以捕捉和再现更多色调。
因此，良好的HDR显示器比典型的SDR屏幕更亮、色彩更丰富。由于HDR(HDR)范围以外的其他原因， HDR显示器的色彩还原可能很差，但在实践中，更好的色彩通常与更好的HDR齐头并进。
HDR色域
那些掌握HDR内容以符合特定HDR标准的人具有定义的色域。杜比视界(Dolby Vision)使用REC.2020广色域。HDR10使用较窄的DCI-P3色域，但比标准高清色域REC.709 更宽(REC.709)。
仅仅因为给定的HDR标准提供了广泛的颜色，这并不意味着每台HDR电视都可以再现所有这些或准确地再现它们。屏幕通常被评为覆盖一定色域的百分比，数字越大越好。
您需要 HDR 内容
如果到目前为止的讨论还不清楚，您需要为您的 4K HDR电视提供HDR内容才能从中受益。不仅如此，电视节目或电影还必须采用电视支持的HDR标准。
例如，Netflix使用两种HDR格式进行流式传输：HDR10和Dolby Vision。Netflix App 会自动检测您的电视和流媒体设备支持的 HDR 类型，然后流(HDR)式传输正确类型的内容。不同(Different)的流媒体服务通常至少支持HDR10。Amazon Prime Video支持HDR10+，部分影片也支持杜比视界(Dolby Vision)。
在收集以HDR制作的物理媒体时，您唯一的选择是 4K超高清(Ultra HD) 蓝光(Blu-ray)。这与标准蓝光(Blu-ray)技术不同，后者仅支持 1080p 分辨率，没有足够的空间来存储 HDR(HDR)信息。您还需要一个UHD 蓝光(UHD Blu-ray)播放器，它还必须支持HDR。
将 SDR 转换为 HDR
通过将SDR(SDR)内容“转换”为HDR，可以充分利用SDR 内容。许多电视都可以选择激活一种伪HDR，在这种情况下分析SDR内容，电视软件会“猜测”如果是(SDR)HDR会是什么样子。
结果可能很复杂，具体取决于电视使用的特定算法。但在许多情况下，它确实提供了增强的画面。
在最新的 Xbox 游戏机上，您还会发现一项名为“ Auto-HDR ”的功能，该功能将HDR信息注入到未使用HDR支持创建的游戏中。这又一次的效果如何，因具体情况而异。
购买 4K HDR 电视(HDR TVs)时要寻找什么
仅仅因为新电视被标记为HDR 4K电视并不意味着您获得了您认为的画质优势。任何带有HDR(HDR)的新电视都有几个方面您应该特别注意。
高级 HDR 标准支持
几乎所有HDR 电视(HDR TVs)都支持HDR10，但您应该避免使用仅(only )支持HDR10的(HDR10)电视(TVs)。尝试使用至少支持HDR10+、Dolby Vision或两者的设备。目前，这是两个最常见的标准，它们比标准HDR10有了显着的进步。
真正的 HDR 合规性
4K 电视上的HDR标签实际上是什么意思？(HDR)重要的考虑因素之一是峰值亮度。亮度(Brightness)以“尼特(Nits)”为单位衡量，优质的HDR 电视(HDR TVs)通常会产生至少 600尼特(Nits)的峰值亮度，而高端HDR 电视(HDR TVs)则可以产生 1000尼特(Nits)或更高的峰值亮度。实际上，许多低端电视只能产生 100-300尼特(Nits)，因此它们无法再现正确的HDR图像。
检查第三方出版物（如RTings或消费者报告(Consumer Reports)）测试的亮度水平始终是一个好主意，以查看您正在考虑的电视是否足够亮以成为HDR显示器。
背光与显示技术
市场上有几种电视技术，它们有不同的方法来产生图像和创造亮度。
OLED（有机发光二极管(Organic Light-emitting Diodes)）通常是最好的HDR显示器。OLED是一种发光技术，这意味着屏幕中的像素会发光。OLED电视可以拥有完美的黑色，因为像素可以非常昏暗甚至完全关闭。尽管大多数OLED(OLEDs)并没有那么亮，但只要您在黑暗的环境中观看，对比度就可以帮助它们产生出色的HDR图像。(HDR)
LED液晶电视(LCD TVs)是您会发现的最常见的电视类型。LCD是一种透射式技术，这意味着光线由背光提供，该背光通过LCD面板照射。这限制了屏幕可以变得多暗，因为当像素关闭时背光仍然会发光。
(New LED)局部调光分区、QLED、 Mini LED和Micro LED等(Micro LED)新的 LED技术使LCD(LCDs)更接近OLED 显示器，而没有(OLED displays)OLED屏幕的缺点。具有许多局部调光区域或Mini LED(Mini LED)技术的LED屏幕可能会比没有调光的侧光式LED产生更好的HDR图像。(HDR)
有限的 HDR 输入
虽然您的电视可能支持HDR甚至提供不错的HDR图像，但它可能并非所有输入都支持HDR。一些中端或低端HDR 电视(HDR TVs)仅支持HDMI输入 1上的HDR 。
因此，如果您有多个 HDR 兼容设备，例如PlayStation 5、Apple TV、Roku或Google TV设备，则您必须使用HDMI 分配器(HDMI splitter)或切换器才能在这两个设备上欣赏HDR内容。如果您有智能电视，那么在电视上运行的任何应用程序都将具有HDR，只要它们支持它。
不支持HDR的设备（例如Nintendo Switch）应插入非HDR输入。好消息是， HDR(HDR)不需要特殊的HDMI电缆。任何(Any)经过认证的HDMI电缆都可以使用。
专业评论很重要
阅读使用专业设备的出版物的专业评论以检查声称的性能是否符合实际性能是至关重要的。只需几分钟即可查看您要购买的 4K HDR电视是否与纸上数字所暗示的一样好。
展望光明的一面
索尼(Sony)、三星(Samsung)和 LG等电视制造商一直在努力推动其产品的HDR并支持多个竞争标准。虽然仍然有人猜测哪种HDR标准将成为最普遍的标准，但您几乎可以买到不支持HDR10或杜比视界的(Dolby Vision)HDR电视。
我们认为普通消费者不应过于关注HDR格式大战。最好注意您正在考虑的电视的核心规格，同时确保您的其他设备（例如游戏机、机顶盒和UHD 蓝光(UHD Blu-ray)播放器）能够与您的电视支持的特定标准兼容。
What Is a 4K High Dynamic Range (HDR) TV?
If you’re in the market for a new HD TV, you’ve probablу noticed that some 4K models also have a feature called HDR (High Dynamic Range).
HDR is a technology that dramatically improves the brightness and contrast of a display. HDR is objectively superior to older TV technology, but not all sets are created equal, and HDR isn’t a monolithic standard. Nonetheless, HDR provides the best TV experience, and we’ll explain why.
The Easy Part: 4K
The easiest part of the technology to understand is the “4K” bit. This simply refers to the resolution of the television. “Resolution” in this context means the number of pixels the TV has. Most “4K” TVs are UHD or “Ultra-high Definition,” which is slightly lower resolution than the proper 4K standard used in professional Hollywood cinematic film production.
A UHD TV has a pixel grid of 3840×2160 pixels. This is an incredible four times the number of pixels in an FHD (Full HD) display. UHD resolution isn’t related to HDR at all. Displays can offer HDR regardless of what resolution they have. For example, 1440p computer monitors and mobile phone panels offer HDR, despite having a lower resolution than 4K UHD.
HDR is something you’ll find almost exclusively paired with 4K or higher resolutions when it comes to television. So it’s no surprise that these two TV specs are spoken of in the same breath.
What Is Dynamic Range?
The dynamic range of a television is essentially the distance between how dark and how bright the screen can get. If that sounds a little like the contrast ratio, you aren’t entirely wrong.
However, dynamic range is more about how much detail can be retained in an image’s darkest and brightest parts before you get “crushed” blacks and “blown out” whites.
You might recall that infamous episode of Game of Thrones where scenes were so dark that many viewers could see nothing but a mushy black image. The show’s creators had pushed so far down the dynamic range that lower-end TVs (which most people have) simply weren’t capable of reproducing the details.
Standard Dynamic Range vs. High Dynamic Range
The dynamic range of content and displays is standardized so that the people who master video content know the limits within which they can work. SDR or Standard Definition Range content results from technological limitations in camera and display technology.
Modern cameras and displays can capture and reproduce a far wider range of brights and darks. Not only that, they can capture and reproduce details within those dark and bright parts of the image that would have been lost before.
All HDR does is widen that range and increase the available information cameras capture and screens can show. If you make content with an SDR camera, you won’t see any improvement on an HDR screen. Likewise, if you put HDR content on an SDR screen, it will look like SDR content.
HDR Standards
There are five HDR standards at the time of writing: HDR10, HDR10+, HLG, Dolby Vision, and Advanced HDR by Technicolor.
HDR10
The most widely-supported HDR standard is HDR10. Virtually all HDR displays support HDR10, and most HDR content is available in HDR10. Other standards improve on this original implementation of HDR, and it’s usually only cheaper sets that only support HDR.
HDR is a relatively simple open standard created by the UHD Alliance, the consortium responsible for defining the UHD resolution standard. For a TV to be HDR10 compliant, it must meet specific technical peak brightness and contrast ratio standards.
The HDR metadata, which is additional information about light levels encoded in HDR content, is static in the case of HDR10. That means the specified brightness and contrast levels are the same regardless of the display or specific scene you’re watching. That’s as opposed to HDR standards that use dynamic metadata, which changes those brightness and contrast values on a per-scene basis.
HDR10+
The UHD Alliance does not define HDR10+. Instead, it’s defined by Samsung, one of the largest TV manufacturers in the world.
As the name suggests, HDR10+ builds on the foundation of HDR10. It does this by adding dynamic metadata, which means that HDR targets are based on the current scene. Samsung has made HDR10+ an open standard just like the original HDR. So anyone can put this certification on their TV if it complies with the on-paper requirements.
Dolby Vision HDR
Dolby Vision is one of the significant HDR standards, and you’ll find a fair number of higher-end TVs and media devices to support it. The latest generation of Xbox consoles supports Dolby Vision, for example.
Dolby Vision certification is somewhat more challenging than HDR10 or HDR10+ since it’s a licensed standard. TVs and other HDR devices must pass their certification to display the Dolby Vision sticker.
This standard uses dynamic metadata. This means the image is adjusted to the capabilities of your particular Dolby-certified HDR TV, which has manufacturer settings built into it that help interpret how to display content mastered in Dolby Vision.
Hybrid Log-Gamma (HLG)
Hybrid Log-Gamma works differently from either HDR10 or Dolby Vision. This standard doesn’t have metadata. It instead uses a calculation to work out what the brightness level should be on an HDR display along an SDR gamma curve.
The standard was developed for broadcasters to allow a single signal to work on both SDR and HDR sets. However, very few 4K TVs currently support HLG so unless there’s a greater level of adoption, HLG has an uncertain future.
Advanced HDR by Technicolor
Technicolor is a name known to anyone who has an interest in cinema. This company pioneered much of the film industry’s display technology.
Advanced HDR by Technicolor is an attempt to bring some of that know-how into HDR, but it’s by far the smallest compared to Dolby Vision and HDR 10, so it’s bound to be an uphill battle.
To make things worse, there are three standards within the Technicolor HDR family: SL-HDR1, SL-HDR2, and SL-HDR3. SL-HDR1 is backward compatible with SDR, making it a viable choice for broadcasts like HLG. SL-HDR2 has dynamic metadata and is the competing standard to HDR10+ and Dolby Vision. SL-HDR3 is still in development.
LG, a major rival to Samsung, tends to include a broader range of supported HDR standards with its TVs, supports Technicolor, and you’ll also see sets with support for this standard sold under the Philips brand.
HDR Affects Color Reproduction
While HDR is mostly about peak brightness and darkness, color is also affected. With the extra luminosity data embedded in HDR video, it becomes possible to capture and reproduce more shades of color.
Therefore, good HDR displays are brighter and more colorful than typical SDR screens. An HDR display can have poor color reproduction for other reasons than its HDR range, but in practice, better color usually goes hand-in-hand with better HDR.
HDR Color Gamut
Those mastering HDR content to comply with specific HDR standards have a defined color gamut. Dolby Vision uses the REC.2020 wide color gamut. HDR10 uses the narrower DCI-P3 gamut, but wider than the standard HD gamut, REC.709.
Just because a given HDR standard offers a wide range of colors, that doesn’t mean every HDR TV can reproduce all of them or do so accurately. Screens are often rated as covering a percentage of a certain color gamut, with higher numbers being better.
You Need HDR Content
If it isn’t clear from the discussion so far, you need to feed your 4K HDR TV with HDR content to get any benefit from it. Not only that, but the TV shows or movies have to be mastered in the HDR standard that your TV supports.
For example, Netflix streams using two HDR formats: HDR10 and Dolby Vision. The Netflix app automatically detects what type of HDR your TV and streaming device supports and then streams the correct kind of content. Different streaming services usually support at least HDR10. Amazon Prime Video supports HDR10+, and some titles are also available in Dolby Vision.
When it comes to collecting physical media mastered in HDR, your only option is 4K Ultra HD Blu-ray. This is different from standard Blu-ray technology, which only supports a 1080p resolution and doesn’t have enough spare room for HDR information. You’ll also need a UHD Blu-ray player, which must also support HDR.
Turning SDR Into HDR
It’s possible to get more out of SDR content by “converting” it into HDR. Many televisions have an option to activate a sort of pseudo-HDR where SDR content is analyzed and the TV’s software “guesses” what it would look like if it were HDR.
The results can be pretty mixed, depending on the specific algorithm the TV uses. But in many cases, it does offer an enhanced picture.
On the latest Xbox consoles, you’ll also find a feature called “Auto-HDR,” which injects HDR information into games that were not created with HDR support. How well this works once again varies on a case-by-case basis.
What to Look For When Buying 4K HDR TVs
Just because a new TV is labeled as an HDR 4K TV doesn’t mean you’re getting the picture quality benefits you think. There are several aspects of any new TV with HDR you should pay careful attention to.
Advanced HDR Standard Support
Virtually all HDR TVs support HDR10, but you should avoid TVs that only support HDR10. Try to go with a set that supports at least HDR10+, Dolby Vision, or both. For now, these are the two most common standards, and they offer a significant step up over standard HDR10.
True HDR Compliance
What does the HDR label on a 4K TV actually mean? One of the essential considerations is peak brightness. Brightness is measured in “Nits,” and good HDR TVs usually produce at least 600 Nits of peak brightness, with high-end HDR TVs making 1000 Nits or more. In practice, many low-end TVs only produce 100-300 Nits, so they can’t reproduce a proper HDR image.
It’s always a good idea to check the brightness levels tested by third-party publications such as RTings or Consumer Reports to see if the TV you’re considering is bright enough to be an HDR display.
Backlight and Display Technology
There are several TV technologies on the market, and they have different approaches to producing images and creating brightness.
OLED (Organic Light-emitting Diodes) are generally the best HDR displays. OLED is an emissive technology, which means that the pixels in the screen produce their light. OLED TVs can have perfect blacks since the pixels can be very dimly lit or even turned off completely. Although most OLEDs don’t get all that bright, the contrast ratio helps them produce fantastic HDR imagery as long as you’re watching in a darkened environment.
LED LCD TVs are the most common type of TV you’ll find. LCD is a transmissive technology, which means that the light is provided by a backlight that shines through the LCD panel. This limits how dark the screen can get since the backlight still shines through when the pixels are off.
New LED technologies such as local dimming zoned, QLED, Mini LED, and Micro LED bring LCDs closer to OLED displays without the drawbacks of OLED screens. An LED screen with many local dimming zones or Mini LED technology will likely produce much better HDR imagery than an edge-lit LED with no dimming.
Limited HDR Inputs
While your TV may support HDR and even offer a decent HDR image, it may not support HDR on all its inputs. Some mid-range or lower-end HDR TVs only support HDR on HDMI input 1.
So if you have multiple HDR-compatible devices, such as a PlayStation 5, Apple TV, Roku, or Google TV device, you’d have to use an HDMI splitter or switch to enjoy HDR content on both devices. If you have a smart TV, any apps running on the TV will have HDR as long as they support it.
Devices that don’t support HDR, such as the Nintendo Switch, should be plugged into non-HDR inputs. The good news is that you don’t need a special HDMI cable for HDR. Any certified HDMI cable will work.
Professional Reviews Matter
It’s vital to read professional reviews by publications that use specialized equipment to check whether the claimed performance measures up to the real-world performance. It only takes a few minutes to see if the 4K HDR TV you want to buy is as good as the on-paper numbers suggest.
Looking On The Bright Side
TV makers such as Sony, Samsung, and LG have been hard at work to push HDR on their products and support several competing standards. While it’s still anyone’s guess which HDR standards will become the most universal, there’s almost no HDR TV you can buy that won’t support HDR10 or Dolby Vision.
We don’t think the average consumer should be too concerned about the HDR format wars. It’s better to pay attention to the core specifications of the TV you’re considering while making sure that your other devices, such as consoles, set-top boxes, and UHD Blu-ray players, will work with the specific standards your TV supports.
