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High-dynamic-range video

The meaning of «high-dynamic-range video»

High-dynamic-range (HDR) is a technology for the way luminance and colors are represented in videos and images. It is contrasted with standard-dynamic-range (SDR), which has become the term for older technology.[1] HDR offers the possibility to represent substantially brighter highlights, darker shadows, more details in both sides, and more colorful colors than what was previously possible.[1][2]

HDR enables better use of displays that have high brightness, contrast, and color capabilities. It does not increase the display's capabilities and not all HDR displays have the same capabilities. HDR content will thus look different depending on the display used.[3]

HDR10, HDR10+, Dolby Vision, and HLG are common HDR formats.[4]

The HDR technology related to displays came about in 2014 first for video.[5] It is now also available for still pictures.[6][7]

Other technologies before HDR improved the image quality by increasing the pixel quantity (resolution and frame rate). HDR improves the pixel quality.[8]

While CRT is not used any more and modern displays are often much higher capacity, SDR format is still based and limited to CRT's characteristics. HDR overcomes those limits.[1]

SDR formats are able to represent up to a maximum luminance level of around 100 nits, while for HDR it goes up to at least 1000 nits and in some formats up to 10,000 nits.[1][9] HDR also supports the representation of lower black levels[2] and more saturated colors (i.e. more colorful colors).[1] The most common SDR formats are limited to Rec. 709/sRGB gamut, while common HDR formats use Rec. 2100 color primaries which is a wide color gamut (WCG).[1][4]

Those are the technical limits of HDR formats. HDR contents are often limited to a peak brightness of 1000 or 4000 nits and DCI-P3 colors, even if they are stored in a higher-capable format.[10][11] Display's capabilities vary and no current display is able to reproduce all the maximal range of brightness and colors that can be stored in HDR formats.

HDR video involves capture, production, content/encoding, and display.

The increased maximum brightness capability can be used to increase the brightness of small areas without increasing the overall image's brightness, resulting in for example bright reflections off of shiny objects, bright stars in a dark night scene, bright and colorful fire, or sunset, bright and colorful light-emissive objects.[2][1][12] Content creators can choose the way they use the increased capabilities. They also can choose to restrain themselves to the limits of SDR even if the content is delivered in an HDR format.[12]

For the creative intents to be preserved, video formats require contents to be displayed and viewed following the standards.

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