High-dynamic-range television

Before HDR, improvements in display fidelity were typically achieved by increasing the pixel quantity (resolution), pixel density, and the display's frame rate. By contrast, HDR improves the perceived fidelity of the existing individual pixels. Standard dynamic range (SDR) is still based on and limited by the characteristics of older cathode-ray tubes (CRTs), despite the huge advances in screen and display technologies since CRT's obsolescence. The shadows or lowlights—the darkest parts of an image—can be darker and more detailed. Dolby Vision IQ and HDR10+ Adaptive adjust the content according to the ambient light. == Formats ==

Since 2014, multiple HDR formats have emerged including HDR10, HDR10+, Dolby Vision, and HLG. Some formats are royalty-free and others require a license. The formats vary in their capabilities. Dolby Vision and HDR10+ include dynamic metadata while HDR10 and HLG do not. HDR10 The HDR10 Media Profile, more commonly known as HDR10, is an open HDR standard announced on 27 August 2015 by the Consumer Technology Association. It is the most widespread of the HDR formats, and is not backward compatible with SDR displays. It is technically limited to a maximum peak brightness of 10,000 nits; however, HDR10 content is commonly mastered with a peak brightness between 1000 and 4000 nits. On HDR10 displays that have lower color volume than the HDR10 content (such as lower peak brightness capability), the HDR10 metadata provides information to help the display adjust to the video. It uses dynamic metadata and is capable of representing luminance levels of up to 10,000 nits. HDR10+ HDR10+, also known as HDR10 Plus, is an HDR video format announced on 20 April 2017. It is the same as HDR10 but with the addition of a system of dynamic metadata developed by Samsung. It is free to use for content creators and has a maximum $10,000 annual license for some manufacturers. It has been positioned as an alternative to Dolby Vision without the same expenses. The format is backwards compatible with SDR UHDTV, but not with older SDR displays that do not implement the Rec. 2020 color standards. It is the same as the HDR10 format, except it lacks metadata. It uses dynamic metadata standardized in CUVA 005-2020. Other formats • Technicolor Advanced HDR: An HDR format which aims to be backward compatible with SDR. • SL-HDR1 (Single-Layer HDR system Part 1) is an HDR standard that was jointly developed by STMicroelectronics, Philips International B.V., and Technicolor R&D France. It was standardised as ETSI TS 103 433 in August 2016. SL-HDR1 provides direct backward compatibility by using static (SMPTE ST 2086) and dynamic metadata (using SMPTE ST 2094-20 Philips and 2094-30 Technicolor formats) to reconstruct an HDR signal from an SDR video stream that can be delivered using existing SDR distribution networks and services. SL-HDR1 allows for HDR rendering on HDR devices and SDR rendering on SDR devices using a single-layer video stream. It is based on a gamma curve. • SL-HDR2 uses a PQ curve with dynamic metadata. • SL-HDR3 uses a HLG curve. • EclairColor HDR is an HDR format that is only used in a professional movie environment. It requires certified screens or projectors and the format is only rarely used. It is based on a gamma curve. Comparison of HDR formats Notes == Displays ==

TV sets with enhanced dynamic range and upscaling of existing SDR/LDR video/broadcast content with reverse tone mapping have been anticipated since the early 2000s. In 2016, HDR conversion of SDR video was released to market as Samsung's HDR+ (in LCD TV sets) and Technicolor SA's HDR Intelligent Tone Management. As of 2018, high-end consumer-grade HDR displays can achieve 1,000 cd/m2 of luminance, at least for a short duration or over a small portion of the screen, compared to 250-300 cd/m2 for a typical SDR display. Video interfaces that support at least one HDR Format include HDMI 2.0a, which was released in April 2015 and DisplayPort 1.4, which was released in March 2016. On 12 December 2016, HDMI announced that HLG support had been added to the HDMI 2.0b standard. HDMI 2.1 was officially announced on 4 January 2017, and added support for Dynamic HDR, which is dynamic metadata that supports changes scene-by-scene or frame-by-frame. Compatibility As of 2020, no display is capable of rendering the full range of brightness and color of HDR formats. Certifications VESA DisplayHDR The DisplayHDR standard from VESA is an attempt to make the differences in HDR specifications easier for consumers to understand. The standard is mainly used in computer monitors and laptops. VESA defines a set of HDR levels; all of them must support HDR10, but not all are required to support 10-bit displays. DisplayHDR is not an HDR format, but a tool to verify HDR formats and their performance on a given monitor. The most recent standard is DisplayHDR 1400, which was introduced in September 2019, with monitors supporting it released in 2020. DisplayHDR 1000 and DisplayHDR 1400 are primarily used in professional work like video editing. Monitors with DisplayHDR 500 or DisplayHDR 600 certification provide a noticeable improvement over SDR displays and are more often used for general computing and gaming. Other certifications UHD Alliance certifications: • Ultra HD Premium • Mobile HDR Premium: for mobile devices. == Technical details ==

HDR is mainly achieved by the use of PQ or HLG transfer function. Transfer function SDR uses a gamma curve transfer function that is based on CRT characteristics and is used to represent luminance levels up to around 100 nits. HDR transfer functions: • PQ, or SMPTE ST 2084,'''''' is a transfer function developed for HDR that is able to represent luminance level up to 10,000 cd/m2. It is the basis of HDR video formats (such as Dolby Vision, It is backward compatible with SDR's gamma curve, and is the basis of an HDR format known as HLG. Color primaries SDR for HD video uses a system chromaticity (chromaticity of color primaries and white point) specified in Rec. 709 (same as sRGB). SDR for SD used many different primaries, as said in BT.601, SMPTE 170M and BT.470. HDR is commonly associated to a WCG (a system chromaticity wider than BT.709). Rec. 2100 (HDR-TV) uses the same system chromaticity that is used in Rec. 2020 (UHDTV). HDR formats such as HDR10, HDR10+, Dolby Vision and HLG also use Rec. 2020 chromaticities. HDR contents are commonly graded on a P3-D65 display. Matrix coefficients Rec. 2100 specifies the use of the RGB, YCbCr or ICTCP signal formats for HDR-TV. and standardized in Rec. 2100. It is defined in both ITU-T H.273 and ISO/IEC 23091-2. Metadata Static metadata Static HDR metadata give information about the whole video. • SMPTE ST 2086 or MDCV (Mastering Display Color Volume): It describes the color volume of the mastering display (i.e., the color primaries, the white point and the maximum and minimum luminance). It has been defined by SMPTE and also in AVC and HEVC standards. • MaxFALL (Maximum Frame Average Light Level) • MaxCLL (Maximum Content Light Level) The metadata do not describe how the HDR content should be adapted to HDR consumer displays that have lower color volume (i.e., peak brightness, contrast and color gamut) than the content. Core components of DMCVT are defined in SMPTE ST 2094-1. DMCVT includes four applications: • ST 2094–10 (from Dolby Laboratories), used for Dolby Vision. • ST 2094–20 (from Philips). Colour Volume Reconstruction Information (CVRI) is based on ST 2094–20. HDR Vivid uses dynamic metadata standardized in CUVA 005-2020. Depending on the Dolby Vision profile (or compatibility level), the base layer can be backward compatible with SDR, HDR10, HLG, UHD Blu-ray or no other format in the most efficient IPTPQc2 color space, which uses full range and reshaping. ETSI GS CCM 001 describes a Compound Content Management functionality for a dual-layer HDR system, including MMR (multivariate multiple regression) and NLQ (non-linear quantization). == Adoption ==

Guidelines Ultra HD Forum guidelines UHD Phase A is a set of guidelines from the Ultra HD Forum for the distribution of SDR and HDR content using Full HD 1080p and 4K UHD resolutions. It requires a color depth of 10 bits per sample, a color gamut of Rec. 709 or Rec. 2020, a frame rate of up to 60 fps, a display resolution of 1080p or 2160p and either standard dynamic range (SDR) or high dynamic range that uses HLG or PQ transfer functions. UHD Phase A defines HDR as having a dynamic range of at least 13 stops (213=8192:1) and WCG as a color gamut that is wider than Rec. 709. Still images HDR image formats The following image formats are compatible with HDR (Rec. 2100 color space, PQ and HLG transfer functions, Rec. 2020 color primaries): • HEIC (HEVC codec in HEIF file format) • AVIF (AV1 codec in HEIF file format) • AVIF alternatively supports gain mapping techniques for backward compatibility with SDR; however, there are no encoders currently available. • JPEG XR • JPEG XL • HSP, CTA 2072 HDR Still Photo Interface (a format used by Panasonic cameras for photo capture in HDR with the HLG transfer function) but existing applications usually do not take into account the absolute luminance value defined in ICC profiles. ISO 21496-1 defines a generic way to add HDR information to SDR formats. A layer of gain map records the luminance ratio between HDR source and its tone-mapped SDR rendering, so that the HDR source signal can be (partially) reconstructed from the SDR layer and this map. Software that does not support the gain map would show the fallback SDR rendering. ISO 21496-1 is a unification of Adobe Gain Map, also known as Google Ultra HDR and Samsung Super HDR, and Apple Gain Map. Apple refers to ISO 21496-1 as Adaptive HDR. Adoption of HDR in still images Apple: iPhone 12 and later support the aforementioned gain map HDR technique for still images. iOS 18, iPadOS 18, and macOS 15 support ISO 21496-1, marketed as Adaptive HDR. Canon: EOS-1D X Mark III and EOS R5 are able to capture still images in the Rec. 2100 color space by using the PQ transfer function, the HEIC format (HEVC codec in HEIF file format), the Rec. 2020 color primaries, a bit depth of 10 bit and a 4:2:2 YCbCr subsampling. The captured HDR pictures can be viewed in HDR by connecting the camera to an HDR display with an HDMI cable. Canon's Digital Photo Professional software is able to show the captured HDR pictures in HDR on HDR displays or in SDR on SDR displays. It is also able to convert the HDR PQ to SDR sRGB JPEG. Google: Android 14 and later support the aforementioned Ultra HDR gain map technique for still images. This is marketed by Samsung as Super HDR. Android 15 and later simultaneously encodes Ultra HDR and ISO 21496-1. Chromium based browsers support Ultra HDR and ISO 21496-1. The captured HDR pictures can be viewed in HDR by connecting the camera to an HLG-compliant display with an HDMI cable. The company also released a plug-in for displaying thumbnails of those HDR images on a PC (for Windows Explorer and macOS Finder). Sony: Sony α7S III and α1 cameras can capture HDR photos in the Rec. 2100 color space with the HLG transfer function, the HEIF format, Rec. 2020 color primaries, a bit depth of 10 bit and a 4:2:2 or 4:2:0 subsampling. The captured HDR pictures can be viewed in HDR by connecting the camera to an HLG-compliant display with an HDMI cable. Web Work is in progress at W3C to make Web compatible with HDR, which includes HDR capabilities detection and HDR in CSS. Chrome and Safari mostly support those in 2024. ==History==

2014 In January 2014, Dolby Laboratories announced Dolby Vision. In October 2014, the HEVC specification incorporates code point for PQ. Previously, it also incorporates the Main 10 profile that supports 10 bits per sample on their first version. In October 2014, SMPTE standardized the Mastering Display Color Volume (MDCV) static metadata in SMPTE ST 2086. 2015 In March 2015, HLG was standardized in ARIB STD-B67. On 8 April 2015, the HDMI Forum released version 2.0a of the HDMI Specification to enable transmission of HDR. The specification references CEA-861.3, which in turn references SMPTE ST 2084 (the standard of PQ). On 24 June 2015, Amazon Video was the first streaming service to offer HDR video using the HDR10 format. On 27 August 2015, Consumer Technology Association announced HDR10. 2016 On 1 March 2016, the Blu-ray Disc Association released Ultra HD Blu-ray with mandatory support for HDR10 and optional support for Dolby Vision. On 9 April 2016, Netflix started offering both HDR10 and Dolby Vision. On June to September 2016, SMPTE standardized multiple dynamic metadata for HDR in SMPTE ST 2094. On 6 July 2016, the International Telecommunication Union (ITU) announced Rec. 2100, which defines the image parameters for HDR-TV and use two HDR transfer functions—HLG and PQ. On 9 September 2016, Google announced Android TV 7.0, which supports Dolby Vision, HDR10, and HLG. On 26 September 2016, Roku announced that the Roku Premiere+ and Roku Ultra will support HDR using HDR10. On 7 November 2016, Google announced that YouTube would stream HDR videos that can be encoded with HLG or PQ. On 17 November 2016, the Digital Video Broadcasting (DVB) Steering Board approved UHD-1 Phase 2 with a HDR solution that supports HLG and PQ. The specification has been published as DVB Bluebook A157 and was published by the ETSI as TS 101 154 v2.3.1. 2019 On 26 December 2019, Canon announced the adoption of the PQ format (PQ10) for still photography. iPhone uses the Dolby Vision profile 8.4 cross-compatible with HLG. 2021 In June 2021, Panasonic announced a plug-in for Photoshop CC to allow for the editing of HLG stills. ==See also==