High dynamic range

High dynamic range (HDR) is a dynamic range higher than what is considered to be standard dynamic range. The term is often used in discussing displays, photography, 3D rendering, and sound recording including digital imaging and digital audio production. The term may apply to an analog or digitized signal, or to the means of recording, processing, and reproducing such signals.

High-dynamic-range imaging (HDRI) is the compositing and tone-mapping of images to extend the dynamic range beyond the native capability of the capturing device.

High-dynamic-range video (HDR video) is greater than standard dynamic range (SDR) video which uses a conventional gamma curve.

High-dynamic-range rendering (HDRR) is the real-time rendering and display of virtual environments using a dynamic range of 65,535:1 or higher (used in computer, gaming, and entertainment technology).

On January 4, 2016, the Ultra HD Alliance announced their certification requirements for a HDR display. The HDR display must have either a peak brightness of over 1000 cd/m2 and a black level less than 0.05 cd/m2 (a contrast ratio of at least 20,000:1) or a peak brightness of over 540 cd/m2 and a black level less than 0.0005 cd/m2 (a contrast ratio of at least 1,080,000:1). The two options allow for different types of HDR displays such as LCD and OLED.

HDR transfer functions that better match the human visual system than a conventional gamma curve include the Hybrid Log-Gamma (HLG) and Perceptual Quantizer (PQ). HLG and PQ require a bit depth of 10-bits per sample.

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