Standard-dynamic-range video

Standard-dynamic-range (SDR) video describes images/rendering/video using a conventional gamma curve, and therefore presenting a dynamic range that is considered standard, as opposed to high-dynamic-range (HDR) video.[1] The conventional gamma curve was based on the limits of the cathode ray tube (CRT) which allows for a maximum luminance of 100 cd/m2.[2][3] The first CRT television sets were manufactured in 1934 and the first color CRT television sets were manufactured in 1954.[4][5]

Technical details

The dynamic range that can be perceived by the human eye in a single image is around 14 stops.[1] SDR video with a conventional gamma curve and a bit depth of 8-bits per sample has a dynamic range of about 6 stops, assuming a luminance quantisation threshold of 5% is used.[1] (A threshold of 5% is used in the paper (instead of the standard 2% threshold) to allow for the typical display being dimmer than ideal.) Professional SDR video with a bit depth of 10-bits per sample has a dynamic range of about 10 stops.[1] Conventional gamma curves include Rec. 601 and Rec. 709.[6] The linear part of the conventional gamma curve was used to limit camera noise in low light video but is no longer needed with high dynamic range (HDR) cameras.[6] An example of a conventional gamma curve would be Rec. 601:

Limitations

While conventional gamma curves are useful for low light video and are compatible with CRT displays, they have a limited dynamic range.[1][2] A transfer function that is closer to Weber's law allows for a larger dynamic range, at the same bit depth, than a conventional gamma curve.[1] HDR standards such as Hybrid Log-Gamma (HLG) and SMPTE ST 2084 allow for a larger dynamic range by using a different transfer function.[1][2] HLG is compatible with SDR displays.[7]

See also

References
  1. T. Borer; A. Cotton. "A "Display Independent" High Dynamic Range Television System" (PDF). BBC. Retrieved 2016-02-02.
  2. "Dolby Vision White Paper" (PDF). Dolby Laboratories. Retrieved 2016-02-02.
  3. Andrew Tarantola (2015-06-24). "How Dolby Vision Works, and How It Could Revolutionize TVs Forever". Gizmodo. Retrieved 2016-02-02.
  4. "15GP22 Color CRT". Early Television Museum. Retrieved 2016-02-02.
  5. "Early Electronic Television". Early Television Museum. Retrieved 2016-02-02.
  6. "Study Group Report High-Dynamic-Range (HDR) Imaging Ecosystem". Society of Motion Picture and Television Engineers. Retrieved 2016-02-02.
  7. "High Dynamic Range" (PDF). European Broadcasting Union. Retrieved 2015-11-01.
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