What is HDR?
Jan 22, 2021• Proven solutions
Technically speaking, all pictures ever created have a dynamic range, since the term denotes the contrast between the brightest and the darkest areas of an image. However, the concept of high dynamic range or (HDR) has only gained significance with the advance of digital images and displays capable of reproducing digital images in their original resolutions.
Confusing HDR with image resolution would be a mistake, as the resolution of an image simply denotes the total number of pixels each frame contains. At the same time, HDR indicates the difference between the brightest and the darkest spots of that frame. Hence HDR is vital for homeowners who are looking for a new TV and aspiring image-makers who are searching for a way to make their pictures brighter and more vivid.
Part 1: What is HDR?
HDR is one of the strongest selling points of 4K TVs because it offers an upgrade from the standard dynamic range that can be found in most HD and Full HD TV sets on the market. This means that a display that is equipped with HDR has the ability to read all the information that an HDR video or photo contains.
Furthermore, HDR videos contain more data than non-HDR videos, which makes all the colors between the brightest and darkest areas of the picture more vibrant. Consequently, TVs that support one of the HDR types are going to show more accurate reds, greens, or blues while at the same time display more details in the shades.
That’s why on HDR-enabled displays you can see the details in the shades that would be completely dark on SDR displays. The same goes for the brightest areas of the image, as the level of detail HDR displays show is much better than on SDR displays.
Currently, nearly all 4K monitors support one or more HDR types, and this feature is definitely something you should look into before you purchase a new 4K TV. However, you should keep in mind that HDR videos, much like 4K content are still relatively difficult to find, as only a handful of online streaming services offer HDR movies. In addition, how much HDR can actually add to the picture quality depends on the TV you have.
Part 2: How Does HDR Work?
All HDR TVs accentuate the brightness of the images they display, and in some cases, the pictures you see on an HDR TV can be five times brighter than those displayed on a non-HDR TV. HDR affects the highlights mostly because the blacks on OLED and LCD TVs are already as dark as they can possibly be.
However, the blacks on LCD TVs are somewhat brighter than those on OLED TVs, which is the reason why you should check if the LCD TV you would like to buy is equipped with the Local Dimming feature.
Electro-Optical Transfer Function is one of the most important technologies HDR TVs use to achieve real-life brightness. The candela per square meter or Nits is the luminance unit that shows the TV’s maximum brightness capacity. Most non-HDR TVs can only go as high as 350 nits, while some high-end HDR TVs can have more than 2000 nits.
What’s more, HDR TVs don’t make an entire image brighter, but rather add more brightness to the areas of the image that need it. If you would like to watch HDR content on a TV that is equipped with the HDR technology, you won’t be able to do it from a regular Blu-ray player, since HDR videos contain much more data than a Blu-ray disc can handle. You will either need an Ultra HD Blu-ray player, and Xbox One S or Xbox One X.
Part 3: How Many HDR Standards are there?
Currently, there isn’t just one uniform HDR standard that applies to all TVs, and different TV manufacturers utilize different standards. That’s why the type of HDR you will find on Sony, LG and Samsung TVs is not the same. So let’s take a look at what different types of HDR have to offer.
This is by far the most common type of HDR that is actively promoted by the UHD Alliance. It is an open standard that can be used by any TV manufacturer for free. What’s more, all HDR-capable TVs are compatible with HDR10, as it is commonly regarded as the minimum requirement for an HDR display.
HDR10 has the maximum brightness of 1000 Nits and 10-bits of color depth which is almost double from what standard dynamic range TVs can provide. Moreover, HDR10 offers the color palette that contains one billion shades, while SDR supports just 16 million shades of color. Even though how much HDR10 can improve image quality depends on the TV set, this HDR type still utilizes static metadata that is the same on every display, which enables it to set color and light values for an entire movie or video clip.
HDR10+ is an upgraded version of HDR that is developed by 20th Century Fox, Panasonic, and Samsung. This HDR type has the maximum brightness capacity of 4000 Nits, which means that its contrast ratio is also significantly higher than the one offered by HDR10.
However, the way these two HDR types process data is completely different since HDR10+ utilizes the dynamic metadata collection process that enables it to change contrast, brightness, and color parameters from one frame to another.
At the moment, HDR10+ is only available on TVs that are manufactured by Samsung and Panasonic, which considerably narrows down your choices if you want to get a TV that has HDR10+ technology. In addition, finding HDR10+ content can prove to be difficult, although things can change in a not so distant future.
3. Doubly Vision HDR
This HDR format was developed by Dolby Labs, and it has already been around for quite some time. Like the HDR10+, Doubly Vision HDR also uses the dynamic metadata approach to feed new color, brightness, and contrast values to each frame that is displayed on the screen.
The maximum brightness capacity exceeds the one provided by the HDR10+ format, as Doubly Vision HDR TVs have 10.000 Nits and 12 bits of color depth. Even so, there are no TVs on the market that can support 12-bit color depth or provide such high brightness capacity. Unlike the HDR10 and HDR10+ that are open source and completely free to use, manufacturers that want to utilize Doubly Vision HDR technology must first purchase the license to do so. It remains to be seen whether HDR10+ or Doubly Vision HDR are going to become the industry standard in the coming years.
4. Hybrid Log-Gamma
This HDR technology was developed by BBC and NHK with the aim of enabling TV stations to broadcast HDR footage live. Unlike other HDR types, Hybrid Log-Gamma doesn’t use the metadata to calculate the brightness, contrast, or color values. Instead, it relies on the gamma curve to calculate the brightness level for an SDR TV and a logarithmic curve to measure the brightness levels for HDR TVs.
The only downside is that major TV stations don’t produce a lot of 4K content, which means that finding Hybrid Log-Gamma content is incredibly difficult. Whether or not TV manufacturers are going to start using this type of HDR is still unclear, because it is a novel technology that is primarily designed for TV broadcasts. However, as 4K content becomes more popular Hybrid Log-Gamma might become an interesting solution because it can adapt to both SDR and HDR screens.
Part 4: HDR FAQs
1. How important is HDR for 4K TVs?
Although it is easy to assume that all TV sets capable of displaying 4K resolutions also have HDR, this is not the case. HDR improves the quality of 4K images, in terms of color vibrancy, contrast and brightness, so if you want to get the most out all 4K videos you play on TV, you should opt for the model that supports one of the commercially available HDR types.
2. Where can I find HDR Content?
Streaming services like Netflix, Amazon Prime Video, Disney+ or Apple TV+ are just a few options you will have if you are looking for HDR content online. Additionally, you can get an Ultra HD Blu-ray player that enables you to play 4K UHD and HDR content. Despite so many available options, the amount of movies you can watch in HDR is still underwhelming.
3. Are TVs that have HDR worth it?
The steep price and content scarcity make TVs that offer support for HDR a relatively risky investment. However, finding HDR content may become easier in the future as several Hollywood studios have stated that they are going to release HDR movies.
4. Which type of HDR is the best?
It is difficult to say which type of HDR is best because each of these technologies is still novel. As time passes it will become clearer if HDR10+ is a better option than Doubly Vision HDR that is currently more popular.
5. What is the difference between HDR for TV and HDR for digital cameras?
Digital cameras can capture HDR photos or videos using image compositing techniques, while TVs that support HDR simply have the capacity to display all the data that an HDR image contains. So, if you take an HDR photo with your Smartphone or record an HDR video you are going to need a display that is capable of reproducing all data in these images accurately.
HDR is undoubtedly one of the most important features of 4K TVs, and you need to pay close attention to it if you are thinking about getting a new 4K TV. This feature is designed to increase a TV’s contrast ratio and improve its color depiction capacity by providing more data. Whether or not the benefits of HDR are going to be clearly visible, ultimately depends on the TV’s quality. Hopefully, this article has helped you understand what HDR is and to create a distinction between HDR functionality on Smartphone camera and 4K TVs.