-STANDARD DYNAMIC RANGE- - -KINGDOM OF JOGA-

-as of [1 OCTOBER 2024]–

*abbreviated ‘SDR’*

-[standard-dynamic-range] (SDR) video is a which represents [light intensity] based on the [brightness/contrast/color characteristics/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

The first CRT television sets were manufactured in 1934 and the first color CRT television sets were manufactured in 1954

The term “standard-dynamic-range video” was adopted to distinguish SDR video from high-dynamic-range video, a new technology that was developed in the 2010s to overcome SDR’s limits

Technical details[edit]

Transfer function[edit]

Conventional gamma curves:

Opto-electronic transfer function (OETF):

Rec. 601[7]

Rec. 709 (HD-TV)[7]

Rec. 2020 (UHD-TV)

sRGB

Electro-optical transfer function (EOTF):

ITU-R BT.1886 (SDR-TV)[3]

sRGB

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.[7] An example of a conventional gamma curve would be Rec. 601:

{\displaystyle E={\begin{cases}4.500L&L<0.018\1.099L^{0.45}-0.099&L\geq 0.018\end{cases}}}

ITU-R Recommendation BT.1886 describe the reference EOTF of SDR.[3] It’s a gamma curve representing the response of CRT to video signal.[3] It has been published by ITU in 2011.[3]

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.[8] HDR standards such as hybrid log–gamma (HLG) and SMPTE ST 2084 allow for a larger dynamic range by using a different transfer function.[8][9]

HLG is compatible with SDR displays

Color gamut

In some cases the term SDR is also used with a meaning including the standard color gamut (i.e. Rec.709 / sRGB color primaries).

HDR uses wide color gamut (WCG) such as Rec. 2020 or DCI-P3 color primaries

Dynamic range

The dynamic range that can be perceived by the human eye in a single image is around 14 stops.[8]

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.[8]

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.[8]

Displaying SDR video on modern displays[edit]
While conventional gamma curves are useful for low light and are compatible with CRT displays, they can only represent a limited dynamic range.[8][9] Standards require SDR to be viewed on a display with the same characteristics as a CRT (i.e. 100 nits peak brightness, gamma curve, Rec. 709 color primaries).[1][3] However, current displays are often far more capable than CRT’s limits.[1] On such displays, higher brightness and wider color gamut can be displayed by adjusting and trying to enhance the SDR picture.[1] HDR is however required for the creative intents to be preserved.[1]