HDR is a term that you frequently come across when you go through features and specifications of TV display. But what does it mean? How does it affect the display? If these are some of the questions that you ponder over, then we shall explain them in this article.
High Dynamic Range ( HDR)
Human eye is an amazing device. We can see colors in all vividity and details with extreme precision. Displays everywhere are trying to mimic this extraordinary device. That is why TV manufacturers often write realistic display, close to real life etc. in their feature list.
The two main feature that determines the display quality in terms of color and details is the contrast ratio and color accuracy.
Contrast ratio refers to the difference in brightness between the darkest black and the brightest white. So if you see a TV with contrast ratio 4500: 1 , it means the brightest white the TV can display is 4500 times brighter than its darkest black. The contrast ratio of OLED TVs is infinite as it can turn off the pixel and make it in to absolute black.
Color accuracy means how close the color in the display is compared to real life.
In fact, experts are of the opinion that if there are two TVs- one with higher resolution and the other with better color contrast and accuracy, you are likely to prefer the latter one, as the images will pop out and look much better in it. So, it is not necessarily about the quantity of pixels, rather it is about the quality of the pixels.
High Dynamic Range, that is HDR increases the range of color accuracy and color contrast. The number of colors displayed by a pixel in an HDR TV is quite higher compared to that of a Standard Dynamic Range(SDR) TV. Thus, color accuracy is better.
The difference between the brightness and darkness is also higher, thereby improving contrast ratio. So, when there is a distinct brightness difference between each pixel, the details are not lost in darkness or brightness. There is a distinct shading that displays details in shadows as well as brightness without missing nuances. Like for example, clouds are not flat, but the color difference between blues and whites are distinct; reflections are clearer, colors are richer with intricate gradation and shading.
To further enhance detailing, manufacturers incorporate features like local dimming, where a region is dimmed while keeping the rest bright, thus highlighting the details.
But TV alone having HDR is not sufficient. The content should also be in HDR format. The good news is that Netflix, Prime and such online streaming applications provide HDR content. However, most cable TV come with HD content, and not HDR content.
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Comparison HDR10, HDR10+,Dolby Vision and HLG
HDR is available in multiple formats namely, HDR10, Dolby Vision, HDR10 Plus and HLG. Let us see how each differ.
HDR10 is the minimum specification of an HDR TV. A TV that supports HDR10 format should be capable of producing 1 billion color shades, maximum brightness of 1,000 nits and color-depth of 10 bits. When compared to standard dynamic range (SDR), that is twice the brightness and contrast. SDR format can reproduce just 16 million colors in comparison.
Being an open format, manufacturers can use HDR10 format free of cost. However each manufacturer is left on their own as to how to implement it. Though standards are set, it is not stringently implemented.
Yet another aspect is that the metadata of HDR10 format is static. This means the color calibration data can be set per show or movie, while in Dolby Vision, it can be set per frame.
HDR10, being free and open is the most popular and widely used.
Dolby Vision is the proprietary standard of Dolby ( yes, the same audio company). Its standards are higher, implemented stringently and a licensing fee has to be paid to Dolby to use it.
In Dolby Vision, metadata can be set dynamically, meaning the color calibration of each frame can be set by the content producers. So, TV that is Dolby Vision compatible can process the scene by scene instruction in terms of contrast, color and brightness and display it on screen.
Dolby Vision facilitates content of brightness up to 10000 nits, and up to 68 billion colors in 12 bit depth.
Dolby Vision is clearly superior in terms of picture quality compared to HDR10 with better contrast, detailing and more tone definition. But not all TVs support Dolby Vision.
You cannot find Dolby Vision in most budget Chinese brand TVs. Even in LG, Sony and Samsung, Dolby Vision compatibility is found only in their premium models.
HDR10+ improves upon HDR10 format taking some of the features from Dolby Vision. The maximum brightness range is extended to 4000 nits and contrast too has been increased correspondingly.
Though it doesn’t have licensing fee like Dolby Vision, HDR10+ is not widely used by most manufacturers. This is mainly because HDR10+ was developed by a consortium of Samsung, Panasonic and 20th Century Fox. So, only Samsung and Panasonic are introducing HDR10+ compatible Televisions. Content side, Amazon Prime supports HDR10+, but not Netflix.
HLG ( Hybrid Log Gama)
HLG was developed by BBC in collaboration with Japan’s NHK. So, it doesn’t come as a surprise that it is intended for cable TV.
Its main advantage is that HLG format can be run on regular Standard Dynamic Range TV as well as TVs compatible with HLG format. So, if your TV is compatible with HLG-HDR, the display is shown as HDR, else, it is shown as SDR ( Standard Dynamic Range) with maximum possible upscale to enhance the picture quality.
TVs manufactured post 2016 by Sony, Samsung and LG have HLG compatibility as a firmware update. HLG compatibility can also be found in certain premium models from Panasonic.
However, no Indian channels provide HLG content. So, even if your TV is compatible, you aren’t likely to exploit its complete benefit for quite some time.
Yet another question frequently asked by many are how does HDR compare to 4K or UHD. Let us find out.
HDR Vs. 4K
Honestly, HDR vs 4K is not quite a sensible comparison. Its like you are trying to compare quantity to quality.
4k or UHD (Ultra High Definition) defines the number of pixels per inch, which is 3840 x 2160 pixels.
HDR, as you would have understood by now, defines the quality of pixel in terms of color accuracy and contrast.
Though HDR has got nothing to do with resolution, HDR compatibility is predominantly seen in UHD TVs. Certain newer model Full HD TV ( 1920 x 1080 pixel) also has HDR compatibility.
As HDR content is predominantly available on streaming apps, HDR compatibility is found mostly in smart TVs.
What To Look For In A TV With HDR?
So, HDR is a format found in most new model TVs, be it Chinese brands or reputed ones like Samsung, Sony and LG. Is it all the same? Not really.
When most TVs say it is HDR compatible, they mean its HDR10 compatibility. As mentioned earlier, HDR10 is an open source which is not strictly enforced. It is up to the manufacturers to ensure that the specifications of the format is actually met. So, when you buy TV from reputed brand, you can be rest assured that the specifications are actually met. Whereas in case of Chinese brands, there might be a chance that the specification is not met diligently.
This issue doesn’t arise in case of Dolby Vision supported TVs as Dolby ensures that the specification is met. But, as mentioned earlier, Dolby Vision is supported only in premium models from reputed brands and not from Chinese brands.
Yet another aspect that you can look for is local dimming feature. Local dimming further enhances the HDR effect, giving best performance.
That being said, if you do not watch Netflix and Prime, or if aren’t in to high end gaming or watching Blu-ray videos, HDR compatibility wouldn’t be of much use to you. Most regional streaming apps like Hotstar and cable TV doesn’t have HDR content.
Note- Amazon and Netflix recommends a minimum internet speed of 15 Mbps and 25Mbps respectively for streaming UHD content, irrespective of whether its HDR or not.
HDR is one of the most important picture quality enhancing feature adopted in TVs. And it is not a marketing gimmick. HDR can truly enhance the contrast, color accuracy and overall picture quality. But, in India, availability of HDR content is limited to Netflix and Prime. So, buying an HDR compatible TV might not be that beneficial to most viewers.