Source: Trusight http://www.trusight.com/
HDR stands for “high dynamic range” and refers to the range from light to dark and what happens in between. Digital camera owners may be familiar with an HDR mode on their cameras which takes multiple pictures with different exposures and combines them into one photo that shows more contrast along with more details in the light and dark areas. HDR in cameras has similarities to what HDR in TVs is but it is not the same thing. HDR in cameras pertains more to the image capture and processing while HDR in TVs is all about what gets displayed.
What is HDR in TVs and Displays?
Samsung SUHD JS9500 http://www.samsung.com/us/video/tvs/UN65JS9500FXZA
HDR in TVs and digital displays is another step in creating better and more realistic looking images. The last “improvement” in TVs was UHD (Ultra High Definition) TV which bumped up the resolution of HDTVs from 2K to 4K. Adding more pixels creates sharper images and fewer “jaggies” however, some viewers have had a hard time discerning the difference in 4K on smaller sized screens. If UHD added more pixels then HDR will make pixels better by increasing dark and light levels and adding more color information in each pixel going from the current 8 bits per color to 10, or 12 or more bits per color. That translates to going from millions of color variations to billions. The resulting improvement in image quality can be quite dramatic with more vivid colors showing more of details like the ripples in water, the texture of clouds or the stars in a night sky. Viewers should find images with more accurate color and details that look more like ones you see in real life. One reaction to HDR is that it makes looking at content on a display similar to looking out a window.
More Contrast and Wider Color SpacE
More dynamic range translates to more contrast as well as more detail in the light areas, dark areas and even all the areas in between. Although it’s not quite nailed yet exactly how wider color gamut gets specified in the HDR standards it looks like it’s tagging along and will be specified in the leading standard called UHD 10 which, so far . Samsung, LG, Sony and Amazon are all behind. Not only will wider color gamut result in more accurate color presentation but and banding will be reduced as well. As a color goes through a change in shades, if there aren’t enough colors available, you could see discreet bands of colors instead of a smooth gradient.
Going Nuts Over Nits
A nit is an expression of luminance that is equivalent to one candela per square meter (cd/m2) which is approximately equal to the light from one candle reflected from a white surface such as a screen or display. The human eye is capable of detecting the presence of light over a very wide range of luminance from the darkness of a millionth of a nit (10-6 ) to over a million nits (106 ). CRT TVs maxed out around 100 nits while newer flat panel TVs bumped up luminance a few hundred nits. The newest tablets deliver ~300 nits and HDR TVs will be at least 700-1000 nits. Movie theaters, on the other hand, are capable of projecting over 1000s of nits onto from the screen. HDR’s goal will be to ultimately increase the luminance in displays as high as practically possible. Keep in mind, that for personal displays like smartphones and tablets, the more you increase luminance, the shorter the battery is going to last, so despite Dolby’s goal for their HDR standard (Dolby Vision) of 10,000 nits most manufacturers will balk at that level.
Images Are Sharper but Standards Are Still FuzzY
One problem with HDR is that there is currently no one accepted standard that defines it although as we stated earlier, it looks like the UHD 10 the prevailing standard at the moment which not only specifies a greater range from light to dark but also a wider color space created with by increased pixel bit depths. This unsettled situation with a coherent standard, has led TV makers to individually brand their own implementations of HDR. In their SUHD TV, Samsung calls theirs “Peak Illuminator Ultimate”, Sony’s HDR is called “X-Tended Dynamic Range,” and LG features “Ultra Luminance,” in its $4500 Prime 4K UHDTV. Panasonic calls theirs, "Dynamic Range Remaster" while Vizio has adopted Dolby’s HDR standard called Dolby Vision.
Dolby is a household name when it comes to audio and now they are promoting their version of HDR for video called Dolby Vision. Journalists who have seen demos of Dolby Vision came away impressed with the level of clarity and realism. In order to play Dolby Vision content you’ll need a compatible display that meets brightness and color gamut requirements. The list of Dolby Vision partners continues to grow with TV manufacturers including Vizio, Philips, and Toshiba along with distributors VUDU, Amazon and Netflix, and content creators like Sony Pictures Home Entertainment. Limiting Dolby Vision adoption might be obstacles like Dolby’s healthy licensing fee.
Expanded Color Space
The Commission internationale de l'éclairage, known commonly as the CIE, produced a color chart that has been used over the years not only to express a range of colors that the human vision system can discern but also what various devices are capable of displaying. Color spaces or “gamut” have been expanding over the years as standards define new ranges for them. The International Telecommunication Union’s (ITU) spec called BT.709 defined the color space for HDTV, and their latest recommended spec BT.2020, expands the color space with increased bit depth.
New Display Technology on the HorizoN
Courtesy Nanosys http://www.nanosysinc.com
In order to accommodate new standards like Rec. 2020 that require displays to produce more colors, along with brighter and sharper images, new display devices will need to be in place to utilize the new improved content. OLED or Organic LED displays don’t require a backlight which means they can produce very dark blacks (all pixels off) and a broader range of colors than other displays. Large sized OLED displays have been costly to produce and expensive to buy and may remain that way for some time. Plasma displays which used phosphors to produce a large range of colors and good contrast were never able to compete with LCD TVs and have been gradually phased out. LCD TVs have seen many improvements over the years including direct backlights and higher resolutions while remaining relatively affordable in larger size screens.
Courtesy Nanosys http://www.nanosysinc.com
LED backlights have replaced the fluorescent backlights of earlier LCD TVs but current LEDs use a combination of blue and yellow to produce a white LED and the result is a color gamut that is barely able to meet the NTSC standard let alone the much more demanding Rec.2020. The latest enhancement to LCDs which may solve that problem is Quantum Dots (QD) which are nanocrystals phosphors that produce a much larger palette of very precise colors. Nanosys is one QD provider that makes a QD film that can be added to LCD backlights at a reasonable cost. Nanocrystals offer a fuller spectrum white backlight with peaks in the red, green and blue wavelengths that makes for a bright, efficient backlight with a wide color space. Some TV manufacturers are already offering QD UHDTVs including Samsung’s 4K SUHD JS9500 which offers “breakthrough nano-crystal color technology” while Sony’s Triluminos TVs are said to use nanocrystals.
Is There Any HDR Content to Watch?
“Mozart in the Jungle” in HDR From Amazon
Movie studios and content creators have been using 4K cameras and creating high resolution content for some time. The fact that there has been no practical way of distributing UHD content either on current Blu-ray discs, over cable or satellite networks or even streaming over the Internet, has given TV buyers a reason to hold off on purchasing a new set. The new 4K Blu-ray player due out soon will help, but only for a small group of consumers. HDR content may not be as taxing to distribute compared to UHD but very little of it has been created and it will be some time before there is lots of content to watch. The high tech camera company, Red has an HDR camera and at least one studio, Warner Brothers has started mastering films in HDR using Dolby Vision on movies including “Edge of Oblivion,” “Man of Steel,” and “The Lego Movie” that can be viewed on Dolby Vision capable devices on VUDU. There are also filters and upscaling technology that will enhance Standard Dynamic Range (SDR) content but consumers will have to wait a little while before native HDR content is available on affordable display devices that are capable of displaying it.
How Long Do You Have to Wait?
There is a veritable alphabet soup of standards bodies including Blu-ray Disc Association, the UHD Alliance, SMPTE, ITU, MPEG, DIGITALEUROPE, EBU, and CEA all promoting slightly different implementations. The problem is compounded as industry segments from the broadcasters to the movie studios all assert the version that best suits their interests. In an industry that has seen struggles over competing standards most recently with 3DTV and before that Blu-ray vs HD DVD, consumers would be justified in adopting a “wait and see,” attitude.
What to Watch While You Wait?
If you’re not convinced that the time is right to upgrade your TV and other devices in order to receive all the enhanced content that has been promised, there are few options to get HDR-quality video without changing anything.
Over the Top (OTT) is the phrase used to describe streaming content over non-proprietary networks. The name, not to be confused with something extravagant, was meant to describe the concept of going over the wall of the garden thus breaking free from the contained, proprietary networks. If you are currently watching movies or TV shows on YouTube, Netflix, Amazon, or one of the many other services, you are watching OTT content. OTT represents a significant threat to the more conventional broadcasts forms including satellite and cable TV. Sending packets of high quality video to digital devices offers lots of flexibility and economies over more conventional broadcasts that require a high bandwidth, fixed connection. Watching “enhanced” content that most devices can receive over the Internet using OTT networks may be a reasonable alternative to buying a new TV and display devices while you wait for HDR content and HDR display devices. Many devices currently available allow you to watch high quality OTT content. For example, you might want to consider buying one of the new reasonably priced, high definition set top boxes like one from Roku or Apple which can receive OTT content via your high speed Internet connection and display it on your current HDTV or UHDTV. Better yet, you may want to join the segment of next generation TV viewers and switch from your television set to a laptop, tablet or smartphone that already has much better display specs than any affordable TV today.
Before consumers embrace HDR and purchase new gear, the industry will have to agree on what constitutes HDR. Content creators will need a “recipe” to follow, the industry will need to know how HDR content gets distributed, how it the HDR content identifies itself to the devices going to display it and how the those devices interprets the HDR data to create “dazzling” images. At this year’s CES show we you are certain you’ll to find HDR in the spotlight with vendors like Samsung, Sony, LG and others showing stunning video on large curved televisions. We’ll keep watching for new products and content as we maintain a healthy skepticism while we continue to look at interim technologies that enhance current devices using current content and infrastructure.