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 a 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]

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:

OpenEXR was created in 1999 by Industrial Light & Magic (ILM) and released in 2003 as an open source software library. [10] [11] OpenEXR is used for film and television production. [11]

Academy Color Encoding System (ACES) was created by the Academy of Motion Picture Arts and Sciences and released in December 2014. [12] ACES is a complete color and file management system that works with almost any professional workflow and it supports both HDR and wide color gamut. [12]

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. [14] [15] 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). [14] [15] The two options allow for different types of HDR displays such as LCD and OLED. [15]

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). [13] [16] [17] HLG and PQ require a bit depth of 10-bits per sample. [13] [16]

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. [18] 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. [19] In April 2007, BrightSide Technologies was acquired by Dolby Laboratories. [20]

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. [21] [22] [23] [24] [25] [26]

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. [27]

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">Dolby</span> Audio technology company

Dolby Laboratories, Inc. is a British-American technology corporation specializing in audio noise reduction, audio encoding/compression, spatial audio, and HDR imaging. Dolby licenses its technologies to consumer electronics manufacturers.

<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">Motion picture film scanner</span> Device that digitises film stock

A motion picture film scanner is a device used in digital filmmaking to scan original film for storage as high-resolution digital intermediate files.

<span class="mw-page-title-main">Digital photography</span> Photography with a digital camera

Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is stored as a computer file ready for further digital processing, viewing, electronic publishing, or digital printing. It is a form of digital imaging based on gathering visible light.

<span class="mw-page-title-main">Exposing to the right</span> Photographic technique

In digital photography, exposing to the right (ETTR) is the technique of adjusting the exposure of an image as high as possible at base ISO to collect the maximum amount of light and thus get the optimum performance out of the digital image sensor.

<span class="mw-page-title-main">Sony camcorders</span> Camcorders produced by Sony

Sony Corporation produces professional, consumer, and prosumer camcorders such as studio and broadcast, digital cinema cameras, camcorders, pan-tilt-zoom and remote cameras.

<span class="mw-page-title-main">Fujifilm FinePix HS</span>

The Fujifilm FinePix HS is a series of bridge cameras that started in February 2010 with the HS10 model. The special feature of the HS cameras is the manual zoom that - otherwise common only with system cameras - allows a quick and precise change of the focal length but demands two-handed operation.

<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 discs are incompatible with existing standard Blu-ray players. Ultra HD Blu-ray supports 4K UHD video at frame rates up to 60 progressive frames per second, encoded using High-Efficiency Video Coding. The discs support both high dynamic range by increasing the color depth to 10-bit per color and a greater color gamut than supported by conventional Blu-ray video by using the Rec. 2020 color space. Ultra HD Blu-Ray discs also support a 12-bit per color container via Dolby Vision. Dolby Vision content on 4K UHD Blu-Ray can also be mastered for 10,000 nits peak brightness, whereas standard HDR10 can only achieve a maximum of 4,000 nits of brightness. Moreover, Dolby Vision makes use of dynamic metadata, which adjusts the brightness and tone mapping per scene. In contrast, standard HDR10 only makes use of static metadata, which sets the same brightness and tone mapping for the entirety of the content.

<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's 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.

<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 Technology 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 has been 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.

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:

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. ↑ "Apple's "EDR" Brings High Dynamic Range to Non-HDR Displays". Prolost. 4 December 2020.
  9. ↑ "Ultra HDR Image Format v1.0". Android Developers. Retrieved 2023-12-19.
  10. ↑ "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.
  11. 1 2 "Main OpenEXR web site". Archived from the original on 16 January 2013. Retrieved 27 July 2016.
  12. 1 2 "ACES". Academy of Motion Picture Arts and Sciences. Archived from the original on 1 August 2016. Retrieved 29 July 2016.
  13. 1 2 3 T. Borer; A. Cotton. "A "Display Independent" High Dynamic Range Television System" (PDF). BBC . Retrieved 2015-11-01.
  14. 1 2 "UHD Alliance Defines Premium Home Entertainment Experience". Business Wire. 2016-01-04. Retrieved 2016-07-24.
  15. 1 2 3 "What is UHD Alliance Premium Certified?". CNET. 2016-03-11. Retrieved 2016-07-24.
  16. 1 2 Adam Wilt (2014-02-20). "HPA Tech Retreat 2014 – Day 4". DV Info Net. Retrieved 2014-11-05.
  17. ↑ Bryant Frazer (2015-06-09). "Colorist Stephen Nakamura on Grading Tomorrowland in HDR". studiodaily. Retrieved 2015-09-21.
  18. ↑ "Our Monitor Picture Quality Tests: Contrast". RTINGS.com. Retrieved 2021-12-29.
  19. ↑ 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.
  20. ↑ "Dolby Laboratories (DLB) Acquires BrightSide for $28M". StreetInsider.com. Retrieved 2021-08-17..
  21. ↑ Quantigraphic camera promises HDR eyesight from Father of AR, by Chris Davies, SlashGear, Sep 12th 2012
  22. ↑ Ackerman, Elise (31 Dec 2012). "Why Smart Glasses Might Not Make You Smarter". IEEE Spectrum. Retrieved 1 Jan 2017.
  23. ↑ 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.
  24. ↑ "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.
  25. ↑ Mann, Steve (Fall 2012). "Through the Glass, Lightly". IEEE Technology and Society Magazine. 31 (3): 10–14. doi:10.1109/MTS.2012.2216592.
  26. ↑ "'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.
  27. ↑ 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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