High dynamic range

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High dynamic range (HDR), also known as wide dynamic range, extended dynamic range, or expanded dynamic range, is a signal with a higher dynamic range than usual.

Contents

The term is often used in discussing the dynamic ranges of images, videos, audio or radio. It may also apply to the means of recording, processing, and reproducing such signals including analog and digitized signals. [1]

Imaging

In this context, the term high dynamic range means there is a large amount of variation in light levels within a scene or an image. The dynamic range refers to the range of luminosity between the brightest area and the darkest area of that scene or image.

High dynamic range imaging (HDRI) refers to the set of imaging technologies and techniques that allow the dynamic range of images or videos to be increased. It covers the acquisition, creation, storage, distribution and display of images and videos. [2]

Modern movies have often been filmed with cameras featuring a higher dynamic range, and legacy movies can be converted even if manual intervention will be needed for some frames (as when black-and-white films are converted to color).[ citation needed ] Also, special effects, especially those that mix real and synthetic footage, require both HDR shooting and rendering.[ citation needed ] HDR video is also needed in applications that demand high accuracy for capturing temporal aspects of changes in the scene. This is important in monitoring of some industrial processes such as welding, in predictive driver assistance systems in automotive industry, in surveillance video systems, and other applications.

Capture

In photography and videography, a technique, commonly named high dynamic range (HDR) allows the dynamic range of photos and videos to be captured beyond the native capability of the camera. It consists of capturing multiple frames of the same scene but with different exposures and then combining them into one, resulting into an image with a dynamic range higher than the individually captured frames. [3] [4]

Some of the sensors on modern phones and cameras may even combine the two images on-chip. This also allows a wider dynamic range being directly available to the user for display or processing without in-pixel compression.

Some cameras designed for use in security applications can capture HDR videos by automatically providing two or more images for each frame, with changing exposure. For example, a sensor for 30fps video will give out 60fps with the odd frames at a short exposure time and the even frames at a longer exposure time.[ citation needed ]

Modern CMOS image sensors can often capture high dynamic range images from a single exposure. [5] This reduces the need to use the multi-exposure HDR capture technique.

High dynamic range images are used in extreme dynamic range applications like welding or automotive work. In security cameras the term used instead of HDR is "wide dynamic range".[ citation needed ]

Because of the nonlinearity of some sensors image artifacts can be common.[ citation needed ]

Rendering

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). [6] HDRR does not require a HDR display and originally used tone mapping to display the rendering on a standard dynamic range display.

Dynamic range compression or expansion

The technologies used to store, transmit, display and print images have limited dynamic range. When captured or created images have a higher dynamic range, they must be tone mapped in order to reduce that dynamic range.[ citation needed ]

Storage

High-dynamic-range formats for image and video files are able to store more dynamic range than traditional 8-bit gamma formats. These formats include:

Transmission to displays

High dynamic range (HDR) is also the common name of a technology allowing to transmit high dynamic range videos and images to compatible displays. That technology also improves other aspects of transmitted images, such as color gamut.

In this context,

On January 4, 2016, the Ultra HD Alliance announced their certification requirements for an HDR display. [23] [24] 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). [23] [24] The two options allow for different types of HDR displays such as LCD and OLED. [24]

Some options to use HDR transfer functions that better match the human visual system other than a conventional gamma curve include the HLG and perceptual quantizer (PQ). [22] [25] [26] HLG and PQ require a bit depth of 10-bits per sample. [22] [25]

Display

The dynamic range of a display refers to range of luminosity the display can reproduce, from the black level to its peak brightness.[ citation needed ] The contrast of a display refers to the ratio between the luminance of the brightest white and the darkest black that a monitor can produce. [27] Multiple technologies allowed to increase the dynamic range of displays.

In May 2003, BrightSide Technologies demonstrated the first HDR display at the Display Week Symposium of the Society for Information Display. The display used an array of individually-controlled LEDs behind a conventional LCD panel in a configuration known as "local dimming". BrightSide later introduced a variety of related display and video technologies enabling visualization of HDR content. [28] In April 2007, BrightSide Technologies was acquired by Dolby Laboratories. [29]

OLED displays have high contrast. MiniLED improves contrast.[ citation needed ]

Realtime HDR vision

Mann's HDR (high-dynamic-range) welding helmet augments the image in dark areas and diminishes it in bright areas, thus implementing computer-mediated reality. MannGlas welding helmet 2views.jpg
Mann's HDR (high-dynamic-range) welding helmet augments the image in dark areas and diminishes it in bright areas, thus implementing computer-mediated reality.

In the 1970s and 1980s, Steve Mann invented the Generation-1 and Generation-2 "Digital Eye Glass" as a vision aid to help people see better with some versions being built into welding helmets for HDR vision. [30] [31] [32] [33] [34] [35]

Non-imaging

Audio

In Audio, the term high dynamic range means there is a lot of variation in the levels of the sound. Here, the dynamic range refers to the range between the highest volume and lowest volume of the sound.

XDR (audio) is used to provide higher-quality audio when using microphone sound systems or recording onto cassette tapes.

HDR Audio is a dynamic mixing technique used in EA Digital Illusions CE Frostbite Engine to allow relatively louder sounds to drown out softer sounds. [36]

Dynamic range compression is a set of techniques used in audio recording and communication to put high-dynamic-range material through channels or media of lower dynamic range. Optionally, dynamic range expansion is used to restore the original high dynamic range on playback.

Radio

In radio, high dynamic range is important especially when there are potentially interfering signals. Measures such as spurious-free dynamic range are used to quantify the dynamic range of various system components such as frequency synthesizers. HDR concepts are important in both conventional and software-defined radio design.

Instrumentation

In many fields, instruments need to have a very high dynamic range. For example, in seismology, HDR accelerometers are needed, as in the ICEARRAY instruments.

See also

Related Research Articles

<span class="mw-page-title-main">Multi-exposure HDR capture</span> Technique to capture HDR images and videos

In photography and videography, multi-exposure HDR capture is a technique that creates high dynamic range (HDR) images by taking and combining multiple exposures of the same subject matter at different exposures. Combining multiple images in this way results in an image with a greater dynamic range than what would be possible by taking one single image. The technique can also be used to capture video by taking and combining multiple exposures for each frame of the video. The term "HDR" is used frequently to refer to the process of creating HDR images from multiple exposures. Many smartphones have an automated HDR feature that relies on computational imaging techniques to capture and combine multiple exposures.

<span class="mw-page-title-main">High-dynamic-range rendering</span> Rendering of computer graphics scenes by using lighting calculations done in high-dynamic-range

High-dynamic-range rendering, also known as high-dynamic-range lighting, is the rendering of computer graphics scenes by using lighting calculations done in high dynamic range (HDR). This allows preservation of details that may be lost due to limiting contrast ratios. Video games and computer-generated movies and special effects benefit from this as it creates more realistic scenes than with more simplistic lighting models. HDRR was originally required to tone map the rendered image onto Standard Dynamic Range (SDR) displays, as the first HDR capable displays did not arrive until the 2010s. However if a modern HDR display is available, it is possible to instead display the HDRR with even greater contrast and realism.

<span class="mw-page-title-main">Tone mapping</span> Image processing technique

Tone mapping is a technique used in image processing and computer graphics to map one set of colors to another to approximate the appearance of high-dynamic-range (HDR) images in a medium that has a more limited dynamic range. Print-outs, CRT or LCD monitors, and projectors all have a limited dynamic range that is inadequate to reproduce the full range of light intensities present in natural scenes. Tone mapping addresses the problem of strong contrast reduction from the scene radiance to the displayable range while preserving the image details and color appearance important to appreciate the original scene content.

<span class="mw-page-title-main">HDR PhotoStudio</span> Discontinued graphics application

HDR PhotoStudio is a discontinued high dynamic range (HDR) graphics application developed by Unified Color for the Windows and macOS operating systems. In addition to being a HDR-merge application, HDR PhotoStudio offered a set of image editing operations that worked in its dynamic range, human color range (gamut), and in high precision. It also had a Color Integrity feature that enabled preserving an image's color tone during image editing operations — for example changing an image's contrast would not change its chromatic data. This problem is usually referred to as "color shift".

<span class="mw-page-title-main">Luminance HDR</span>

Luminance HDR, formerly Qtpfsgui, is graphics software used for the creation and manipulation of high-dynamic-range images. Released under the terms of the GPL, it is available for Linux, Windows and Mac OS X. Luminance HDR supports several High Dynamic Range (HDR) as well as Low Dynamic Range (LDR) file formats.

<span class="mw-page-title-main">Dolby Vision</span> Set of technologies by Dolby Laboratories

Dolby Vision is a set of technologies developed by Dolby Laboratories for high dynamic range (HDR) video. It covers content creation, distribution, and playback. It includes dynamic metadata that define the aspect ratio and adjust the picture based on a display's capabilities on a per-shot or even per-frame basis, optimizing the presentation.

<span class="mw-page-title-main">Ultra HD Blu-ray</span> Optical disc storage medium

Ultra HD Blu-ray is a digital optical disc data storage format that is an enhanced variant of Blu-ray. Ultra HD Blu-ray supports 4K UHD video at frame rates up to 60 progressive frames per second, encoded using High-Efficiency Video Coding. These discs are incompatible with existing standard Blu-ray players.

<span class="mw-page-title-main">Hybrid log–gamma</span> High dynamic range standard that was jointly developed by the BBC and NHK

The hybrid log–gamma (HLG) transfer function is a transfer function jointly developed by the BBC and NHK for high dynamic range (HDR) display. It is backward compatible with the transfer function of SDR. It was approved as ARIB STD-B67 by the Association of Radio Industries and Businesses (ARIB). It is also defined in ATSC 3.0, Digital Video Broadcasting (DVB) UHD-1 Phase 2, and International Telecommunication Union (ITU) Rec. 2100.

High Efficiency Image File Format (HEIF) is an international standard defined by MPEG-H Part 12, first published by ISO in 2017. It is designed as a container for photographic images in any image encoding. HEIF is a special case of the general ISO BMFF format, in which all data is encapsulated in typed boxes, with a mandatory ftyp box that is used to indicate particular file types. The initial specification for HEIF provided usage details for three compression schemes, the widely supported JPEG encoding for still raster images and two video encodings that are also applicable to still image items, namely Advanced Video Coding and High Efficiency Video Coding.

<span class="mw-page-title-main">HDR10</span> Open HDR standard

HDR10 Media Profile, more commonly known as HDR10, is an open high-dynamic-range video (HDR) standard announced on August 27, 2015, by the Consumer Electronics Association. It is the most widespread HDR format.

Standard-dynamic-range video is a video technology which represents light intensity based on the brightness, contrast and color characteristics and limitations of a cathode ray tube (CRT) display. SDR video is able to represent a video or picture's colors with a maximum luminance around 100 cd/m2, a black level around 0.1 cd/m2 and Rec.709 / sRGB color gamut. It uses the gamma curve as its electro-optical transfer function.

<span class="mw-page-title-main">Ultra HD Forum</span> Organization

Ultra HD Forum is an organization whose goal is to help solve the real world hurdles in deploying Ultra HD video and thus to help promote UHD deployment. The Ultra HD Forum will help navigate amongst the standards related to high dynamic range (HDR), high frame rate (HFR), next generation audio (NGA), and wide color gamut (WCG). The Ultra HD Forum is an industry organisation that is complementary to the UHD Alliance, covering different aspects of the UHD ecosystem.

ITU-R Recommendation BT.2100, more commonly known by the abbreviations Rec. 2100 or BT.2100, introduced high-dynamic-range television (HDR-TV) by recommending the use of the perceptual quantizer or hybrid log–gamma (HLG) transfer functions instead of the traditional "gamma" previously used for SDR-TV.

The perceptual quantizer (PQ), published by SMPTE as SMPTE ST 2084, is a transfer function that allows for HDR display by replacing the gamma curve used in SDR. It is capable of representing luminance level up to 10000 cd/m2 (nits) and down to 0.0001 nits. It was developed by Dolby and standardized in 2014 by SMPTE and also in 2016 by ITU in Rec. 2100. ITU specifies the use of PQ or HLG as transfer functions for HDR-TV. PQ is the basis of HDR video formats and is also used for HDR still picture formats. PQ is not backward compatible with the BT.1886 EOTF, while HLG is compatible.

High-dynamic-range television (HDR-TV) is a technology that uses high dynamic range (HDR) to improve the quality of display signals. It is contrasted with the retroactively-named standard dynamic range (SDR). HDR changes the way the luminance and colors of videos and images are represented in the signal, and allows brighter and more detailed highlight representation, darker and more detailed shadows, and more intense colors.

AV1 Image File Format (AVIF) is an open, royalty-free image file format specification for storing images or image sequences compressed with AV1 in the HEIF container format. It competes with HEIC, which uses the same container format built upon ISOBMFF, but HEVC for compression. Version 1.0.0 of the AVIF specification was finalized in February 2019. Version 1.1.0 was finalized in April 2022.

HDR10+ is a high dynamic range (HDR) video technology that adds dynamic metadata to HDR10 source files. The dynamic metadata are used to adjust and optimize each frame of the HDR video to the consumer display's capabilities in a way based on the content creator's intentions.

Images and videos use specific transfer functions to describe the relationship between electrical signal, scene light and displayed light.

High dynamic range (HDR) may refer to:

Ultra HDR (High Definition Range) is an image format that utilizes improved implementation of existing HDR technology to enhance the visual perception of photos on HDR displays via a luminance modulation technique called gain mapping which reallocates pixel intensity on a per-pixel basis based on its spatial factors. This format was engineered by Google in 2023 and first deployed on the Android 14 operating system.

References

  1. ↑ Robertson, Mark A.; Borman, Sean; Stevenson, Robert L. (April 2003). "Estimation-theoretic approach to dynamic range enhancement using multiple exposures". Journal of Electronic Imaging. 12 (2): 220, right column, line 26219–228. Bibcode:2003JEI....12..219R. doi:10.1117/1.1557695. The first report of digitally combining multiple pictures of the same scene to improve dynamic range appears to be Mann
  2. ↑ Dufaux, Frédéric; Le Callet, Patrick; Mantiuk, Rafal; Mrak, Marta (2016). High Dynamic Range Video – From Acquisition to Display and Applications. Elsevier. doi:10.1016/C2014-0-03232-7. ISBN   978-0-08-100412-8.
  3. ↑ "Compositing Multiple Pictures of the Same Scene", by Steve Mann, in IS&T's 46th Annual Conference, Cambridge, Massachusetts, May 9–14, 1993
  4. ↑ Reinhard, Erik; Ward, Greg; Pattanaik, Sumanta; Debevec, Paul (2005). High dynamic range imaging: acquisition, display, and image-based lighting. Amsterdam: Elsevier/Morgan Kaufmann. p. 7. ISBN   978-0-12-585263-0. Images that store a depiction of the scene in a range of intensities commensurate with the scene are what we call HDR, or "radiance maps". On the other hand, we call images suitable for display with current display technology LDR.
  5. ↑ Arnaud Darmont (2012). High Dynamic Range Imaging: Sensors and Architectures (First ed.). SPIE press. ISBN   978-0-81948-830-5.
  6. ↑ Simon Green and Cem Cebenoyan (2004). "High Dynamic Range Rendering (on the GeForce 6800)" (PDF). GeForce 6 Series. nVidia. p. 3.
  7. ↑ Chan, Eric (Adobe); Hubel, Paul M. (Apple) (January 2023). Embedded Gain Maps for Adaptive Display of High Dynamic Range Images. Stereoscopic Displays and Applications XXXIV.
  8. ↑ Benz, Greg (2024-09-27). "What do Apple's latest updates mean for HDR photography?". Greg Benz Photography. Retrieved 2024-11-10.
  9. 1 2 Rahman, Mishaal (2024-10-29). "Google and Apple are making HDR photos work better on Android and iOS". Android Authority. Retrieved 2024-11-10.
  10. 1 2 Benz, Greg (2022-08-24). "Create and edit true HDR (High Dynamic Range) images". Greg Benz Photography. Retrieved 2024-11-10.
  11. 1 2 Chan, Eric. "Gain Maps, Version 1.0 draft 14" (PDF). October 7, 2023. Retrieved 20 June 2024.
  12. 1 2 "Ultra HDR Image Format v1.1". Android Developers. Retrieved 2024-11-10.
  13. ↑ Romero, Andrew (2024-04-02). "Samsung's Super HDR is not coming to older Galaxy devices". 9to5Google. Retrieved 2024-11-11.
  14. ↑ Benz, Greg (2022-08-24). "HDR - AVIF: the future of HDR". Greg Benz Photography. Retrieved 2024-11-11.
  15. ↑ Benz, Greg (2022-08-24). "HDR Standards". Greg Benz Photography. Retrieved 2024-11-11.
  16. ↑ "Apple's "EDR" Brings High Dynamic Range to Non-HDR Displays". Prolost. 2020-12-04. Retrieved 2024-11-11.
  17. ↑ "ISO/IEC JTC 1/SC29/WG1" (PDF). 9–15 April 2018. Retrieved 21 February 2021.
  18. ↑ "Press Release - A New Hybrid Full-Frame Mirrorless Camera, the LUMIX S5 Featuring Exceptional Image Quality in High Sensitivity Photo/Video And Stunning Mobility" (PDF). Retrieved 21 February 2021.
  19. ↑ "Industrial Light & Magic Releases Proprietary Extended Dynamic Range Image File Format OpenEXR to Open Source Community" (PDF) (Press release). 22 January 2003. Archived from the original (PDF) on 21 July 2017. Retrieved 27 July 2016.
  20. 1 2 "Main OpenEXR web site". Archived from the original on 16 January 2013. Retrieved 27 July 2016.
  21. 1 2 "ACES". Academy of Motion Picture Arts and Sciences. Archived from the original on 1 August 2016. Retrieved 29 July 2016.
  22. 1 2 3 T. Borer; A. Cotton. "A "Display Independent" High Dynamic Range Television System" (PDF). BBC . Retrieved 2015-11-01.
  23. 1 2 "UHD Alliance Defines Premium Home Entertainment Experience". Business Wire. 2016-01-04. Retrieved 2016-07-24.
  24. 1 2 3 "What is UHD Alliance Premium Certified?". CNET. 2016-03-11. Retrieved 2016-07-24.
  25. 1 2 Adam Wilt (2014-02-20). "HPA Tech Retreat 2014 – Day 4". DV Info Net. Retrieved 2014-11-05.
  26. ↑ Bryant Frazer (2015-06-09). "Colorist Stephen Nakamura on Grading Tomorrowland in HDR". studiodaily. Retrieved 2015-09-21.
  27. ↑ "Our Monitor Picture Quality Tests: Contrast". RTINGS.com. Retrieved 2021-12-29.
  28. ↑ Seetzen, Helge; Whitehead, Lorne A.; Ward, Greg (2003). "54.2: A High Dynamic Range Display Using Low and High Resolution Modulators". SID Symposium Digest of Technical Papers. 34 (1): 1450–1453. doi:10.1889/1.1832558. ISSN   2168-0159. S2CID   15359222.
  29. ↑ "Dolby Laboratories (DLB) Acquires BrightSide for $28M". StreetInsider.com. Retrieved 2021-08-17..
  30. ↑ Quantigraphic camera promises HDR eyesight from Father of AR, by Chris Davies, SlashGear, Sep 12th 2012
  31. ↑ Ackerman, Elise (31 Dec 2012). "Why Smart Glasses Might Not Make You Smarter". IEEE Spectrum. Retrieved 1 Jan 2017.
  32. ↑ Mann, Steve (February 1997). "Wearable Computing: A First Step Toward Personal Imaging". IEEE Computer. 30 (2): 25–32. doi:10.1109/2.566147. S2CID   28001657.
  33. ↑ "A magical welding helmet that lets you see the world in HDR–in real-time". Archived from the original on 2016-03-28. Retrieved 2018-03-24.
  34. ↑ Mann, Steve (Fall 2012). "Through the Glass, Lightly". IEEE Technology and Society Magazine. 31 (3): 10–14. doi:10.1109/MTS.2012.2216592.
  35. ↑ "'GlassEyes': The Theory of EyeTap Digital Eye Glass, supplemental material for 'Through the Glass, Lightly'" (PDF). IEEE Technology and Society Magazine. 31 (3). Fall 2012.
  36. ↑ EA DICE/Electronic Arts (2007). "Battlefield: Bad Company - Frostbite Engine Trailer" (video). Electronic Arts. Archived from the original on 2021-12-22.
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