Greener BeeGreen ElectronicsDolby Vision versus HDR-10 TV: A format war and more

4K UHD (2160p resolution) is no longer the big news in TV land. HDR (High Dynamic Range) has supplanted it in the conversation. Why? It’s not lack of detail, insufficient pixels, or 1080p resolution in general that’s been the major issue with TVs for the last few years. It’s been the lack of contrast and washed-out colors caused by the adoption of thin-enabling, energy-saving, but color-challenged LED backlighting.

HDR and the technologies that enable it—less leaky LCDs, better backlighting, improved LED/phosphor combinations, quantum dots, to name a few—take contrast to historically high levels, provide an unprecedented level of detail in both dark and bright areas, and as a corollary effect, restore the color we once had with CRTs and LED panels backlit by CCFLs (cold cathode fluorescent lamps). Note that these are largely improvements affecting LED LCD TVs. OLED TVs have been colorful and largely capable of rendering HDR-like images for a while.

richer paint left Dolby

Dolby needs to up its game with its HDR comparison images. It looks a lot better than this.

Just about everyone who’s seen HDR, which can be implemented at any resolution, finds it significantly more compelling than simply adding pixels; but combine 2160p resolution and HDR in properly mastered content and—yowsers! Sadly, something of a format war has arisen, albeit an odd and not particularly scary one. More on that later.

What is HDR?

HDR is essentially a greater differential between the brightest and darkest points in an image, aka the luminance dynamic range or comparative luminance. It’s not about peak brightness, as some believe. OLEDs, with their deep blacks, don’t need to generate as many nits (a measure of luminance) to accomplish the effect. That’s why OLED TVs seem so lush and saturated compared to LED-backlit LCD TVs and their grayish blacks. Both produce similar brightness, but OLEDs have that nearly pure darkness. LED/LCD TVs need to increase peak brightness significantly to achieve the HDR effect.

You’ll also want to read OLED vs LED: There’s just no comparison

You might already be familiar with HDR from photography. Indeed, there’s an HDR option on most phone cameras these days. HDR photos are created by capturing the same exact image multiple times with a range of f-stops, and then combining them. HDR video is pretty much the same deal, only harder to accomplish because capturing a wide range of luminance continuously in real time requires a fair amount of processing power—or multiple cameras. HDR animation or digital effects is easy—just move a slider.

To give you an idea of the difference, several HDR/non-HDR comparison shots are scattered about this article (these were provided by Dolby). If you’re viewing it on an WLED (white LED, as most less-expensive TVs use) display, you’re not getting the full impact, but it should still get the point across.

dolbyhdr

Note that HDR images quite often exaggerate reality.

More colors help

Greater comparative luminance isn’t the only thing required if you want to do HDR right. To avoid ugly artifacts such as banding (as seen below), there must also be a large range of colors available to smooth transitions, as well as provide detail in very bright or dark areas. This is known now as wide color gamut and means 10- to 12 bits per color (that’s approximately one billion or four billion colors). Below is an image in its original 8-bit color; the one below it was downscaled to 4-bit color.

8 bit

This is the original image shot in 8-bit (24-bit in photo-speak) color.

4 bit

Notice the loss of detail and the introduction of more artifacts when you remove color information. The pixel resolution is the same.

Notice the loss of detail and the introduction of artifacts as you lose color resolution. The difference between 8-bit, 10-bit, and 12-bit color isn’t quite as salient as what’s shown above, but it is noticeable. 

Article source: http://www.techhive.com/article/3074897/consumer-electronics/dolby-vision-versus-hdr-10-tv-a-format-war-and-more.html


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