What Is HDR and How Does It Improve TVs and Displays?

TVs and video displays have evolved over the years, bringing us new experiences like never before. New standards have made videos more realistic than ever, and HDR is one of such standards.

If you would like to learn more about what HDR is and how it improves video technology, this article is for you.

What Does HDR Mean?

HDR, or high dynamic range, is a TV and video display feature. Devices that support HDR usually offer brighter highlights and a wider range of color detail. This makes images on the TV or display device punchier and more lifelike.

What Does HDR Do?

HDR video technology provides the standards for a new era of TV and video display. The technology reproduces what we see with our eyes in colors, making videos look as realistic as possible. This is achieved through different factors, including:

Peak brightness.

Black levels.

Color palette.

Transfer functions.

Bit depth.

Metadata.

HDR video makes it possible to recreate image realism from camera through post-production to distribution and display. Information is used in post-production to grade content and get the widest possible contrast range.

In grading the images, deeper and more saturated colors with smoother shading can be applied to the video.

The technology uses the following actions to deliver the visual experience of videos:

Creates more defined contrasts and richer colors.

Increases dynamic range (peak brightness and black levels).

Expands color space (wide color gamut).

Improves image fidelity (10-bit color depth and 1024 color shades).

Updates to an optoelectronic transfer function.

Offers static and dynamic metadata.

Contrast and Color

Contrast deals with the relationship between light and dark and color. The use of contrast with HDR helps define how scenes in videos look. A sunset is one example. In such a scene, HDR preserves the gradation from dark to light in ways that SDR (standard dynamic range) cannot.

Similar to how high-resolution music brings the artist to your ears, HDR goes beyond providing realistic visuals to actually styling them.

Check out our PAMI paper on #sim2real transfer for High Speed and High Dynamic Range Video Reconstruction with an #EventCamera! We show we can render high speed phenomena, e.g. bullet hitting an object!
Paper, code and datasets: https://t.co/Ol24jP5lRR@supitalp #UZH_en pic.twitter.com/8BlwO55FhT
— Davide Scaramuzza (@davsca1) January 20, 2020

Given the choice between a TV with a better contrast ratio and more accurate color or a TV with just a higher resolution, most people choose the device with the greater contrast ratio. This is because of the more natural visuals, which look more real than a TV with a higher resolution.

HDR produces deeper and more vivid reds, greens, and blues while also showing more shades in between for videos. This means that deep shadows in videos won’t just be black voids. Instead, users see details in the darkness, even when the video is very dark. The different shades of objects in the light are also much clearer, with reduced saturation levels for objects.

Light and Brightness

Light plays a critical role in how HDR improves the quality of videos on TV. HDR controls how much light a video puts out. The amount of light put out on the screen affects dynamic range, which is the difference between light and dark on-screen.

Related: How to Calibrate HDR Mode in Windows 10

Our perception of light affects the range of color we perceive. The greater the range of light, the wider the variety of colors we perceive. The range of colors within the spectrum of identifiable colors by the human eye is known as the color gamut. HDR uses a color gamut known as Rec.2020. This gamut shows over 100 times more color than standard display resolution.

Without HDR, the display brightness is usually expressed in “nits” of peak brightness. This changes with HDR, which is designed to go up to 10,000 nits. This is between 30 and 40 times more than what non-HDR displays achieve.

Metadata

HDR metadata contains content and properties used to adjust the color and brightness of a display device.

Tone mapping plays a critical role in how metadata is used with HDR. The process of tone mapping ensures that the color volume of content can be adjusted to the capabilities of a display.

At the same time, however, the imagery retains as much of the original creator’s intentions for displaying the content. Dynamic metadata and static metadata are used with HDR to achieve this.

Related: Dolby Vision vs. HDR10 vs. HLG: The Best HDR TV Screen

Dynamic metadata gives information about specific parts of videos, while static metadata gives information about the whole video. It performs tone mapping on a per scene basis, leading to a better experience when videos are displayed on less capable HDR display devices.

The use of static metadata with HDR may result in greater compression of dynamic range and color gamut than needed. This is because if tone mapping is performed based on static metadata, it will be based on the brightest frame in the whole video.

The Difference Between HDR and Non-HDR

Comparing HDR features to pre-existing TV screens or display technology, such as 4K TV, helps to understand better how much HDR can improve video technology.

4K TV displays are loved because they can produce four times the number of pixels of any HD TV on the market. Yet, when compared against the quality of an HDR TV, many find that they cannot see the type of colors and dynamic pictures possible with HDR TVs.

While 4K defines the number of pixels, HDR defines the quality of what is seen. 4K without HDR does not look as good. Ironically, many people cannot even see the extra resolution that 4K provides in videos.

While certain hues (such as very saturated colors) are visible on HDR displays, you cannot see them on normal TVs, projectors, or computers.

Limitations of HDR

Not all HDR technology is created equal. Cheaper LCD HDR screens do not always meet expectations to display bright objects against sharply darker backgrounds. This causes halos to be created around bright objects or for streaks of light to run down the screen.

Producing HDR can be very challenging. The process may require new equipment and time to learn about the different HDR standards, color space concepts, and more.

Because of this, relatively few people have delivered HDR videos to users of computer devices. This makes the HDR experience of many computer owners lower than those of HDR TV owners.

Source: https://www.makeuseof.com/what-is-hdr/

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