HDR (High Dynamic Range) acronym first appeared at the CES 2016. High in this case referred to a higher peak brightness and greater black depth compared to the traditional SDR range. The emergence of this technology is a logical continuation of the development of digital technologies in the TV segment, because their new generation already provided an image playback with a much higher quality. In particular, the almost instantaneous pixel switching time in OLED matrices, and FALD in LED TVs expanded ranges of contrast and detail.
As known, increasing the brightness gradations extends the variety of displayed combinations of blue, red, green and their shades.
The list of modern television standards includes Rec.709, DCI-P3 and Rec.2020 / 2100. HDR10 and Dolby Vision use the DCI-P3 and Rec.2020 / 2100, the color damut of which significantly exceeds HD in the Rec.709 standard.
In fact, HDR TV expands the color gamut, increasing the saturation and color accuracy with the help of 12 bit color depth. In turn, increasing the range of contrast and color accuracy directly affect the realism and volume of the image. As a result, the screen displays a significantly brighter saturated image.
In general, new HDR technology includes three main components. In particular, it requires a TV with support for HDR format, a broadcast standard for transmitting HDR content and video in HDR format. Each of them, in turn, requires solving complex engineering problems. In addition, their matching also causes some problems.
Some features of HDR-technology
The distortion of the original directorial color and lighting solutions in the frame illustrates this situation well. For example, the creation of modern video content uses an extensive palette of colors within the digital cinematic DCI-P3 standard. But traditional SDR-TVs use a narrower standard Rec.709 that does not display many shades. As a result, the viewer perceives such content much paler. Therefore, TV versions often use special mastering to improve color accuracy.
HDR-TVs do not have this limitation and can adjust the color scheme using their own algorithms. But, of course, it distorts the content originality. Therefore, engineers complement the video signal with metadata with information for converting an SDR image to HDR.
Metadata contains accurate information about the areas of the required dimming, brightening, adding red, purple, etc. Only in this case, TV will be able to accurately reproduce the original directorial content.
But the transfer of metadata required an additional extension of the HDMI standard. As known, HDMI 2.0 supports the transfer of only static data. HDMI 2.0a is the first standard to support the transfer of dinamic metadata. HDMI 2.1 – is its further improvement. At CES 2019, LG introduced the first 4K OLED TVs with HDMI 2.1 support.
Thus, technology requires HDR-content. Of course, the technology of its creation is much more complicated compared to SDR. HDR format requires the creation of metadata for each frame and their dynamic transmission for playback without distortion.
Therefore, initially, the market offered a very limited HDR content. In fact, only Amazon, Netflix and Vudu services offered a small number of films in this format.
However, Technicolor company developed and proposed a set of “Intelligent Tone Management” utilities for converting SDR content into pseudo-HDR. This technology has significantly optimized the restoration of original content, expanding the prospects of HDR. As a result, in the last years we see a rapid expansion of its range.
Technicolor was the first to use remastering to reformat popular black-and-white films, including the iconic The Wizard of Oz.
Further, company founded the UHD Alliance. Using their own development, Technicolor offered a platform broadcast with video on demand M-Go. Today Samsung has an exclusive agreement for its TVs, by analogy with Ultra HD content.
The company is developing HDR technology for broadcast television and HDR-compatible set-top boxes.
As known, Netflix is a pioneer in 4K / Ultra HD streaming. Today, it’s actively working with HDR technology, promising the appearance of HDR – content by the end of this year. The company is also working on HDR-remastering of its own video, including Marco Polo.
After the full launch of this technology, the system will be able to determine the HDR compatibility of your TV and accordingly select the available content.
Amazon company also announced its intention to create original TV content with HDR support.
Ultra HD Blu-ray
Of course, a high level of compression to stream high-quality video content significantly limits the broadcast. Blu-ray discs with their huge capacity have virtually no such limitations. Not surprisingly, the company also decided to join a new promising direction.
Today, the Blu-ray Disc Manufacturers Association is working on new-generation 4K UHD Blu-ray discs with support for 4K, HDR, enhanced color reproduction and surround audio codecs, including Dolby Atmos and DTS: X. In addition, the new HDMI 2.0a standard significantly accelerated this process by expanding the range of models with HDR support, including new Blu-ray players and set-top boxes.
Of course, today support for HDR is one of the important criteria for choosing a TV.
4K HDR LG OLED demo video perfectly illustrates the great features of HDR technology.