Transfer functions in imaging
This article is about the transfer functions used in pictures and videos and describing the relationship between electrical signal, scene light and displayed light.
Definition
The opto-electronic transfer function (OETF) is the tranfer function having the scene light as input and converting into the picture or video signal as output. This is typically done within a camera.[1]
The electro-optical transfer function (EOTF) is the tranfer function having the picture or video signal as input and converting it into the linear light output of the display.[1] This is done within the display device.
The opto-optical transfer function (OOTF) is the transfer function having the scene light as input and the displayed light as output. The OOTF is the result of the OETF and the EOTF and is usually non-linear.[1]
List of transfer functions
A Linear tranfer function describe is a tranfer function based on a linear function. Some EOTF and OETF have an initial linear portion folowwed by a non-linear part (i.e. sRGB, Rec.709[2] and Rec.1886[3]).
Rec.601, Rec.709 and Rec.2020
The ITU-R recommendations BT.601, BT.709 and BT.2020 describe the reference OETF of respectively SD-TV, HD-TV and UHD-TV. They are identical OETF based on a gamma curve and used for SDR-TV.[4][2][5]
Rec.1886
The ITU-R Recommendation BT.1886 describe the reference EOTF of SDR-TV.[3]
sRGB
sRGB defines a transfer function based on a gamma curve and used for monitors, printers, and the Web. It is standardized as IEC 61966-2-1:1999[6]
Other
PQ
The perceptual quantizer (PQ) is a transfer function developed by Dolby for HDR and allowing a a luminance level of up to 10,000 cd/m2. It is standardized as SMPTE ST 2084.[7]
HLG
Hybrid Log-Gamma (HLG) is a transfer function developed by the BBC and NHK for HDR and offering some backward compatibility with SDR.
Transfer functions in codecs
HEVC
References
- ^ a b c "BT.2100 : Image parameter values for high dynamic range television for use in production and international programme exchange". www.itu.int. Retrieved 2021-02-02.
{{cite web}}: no-break space character in|title=at position 8 (help) - ^ a b "BT.709 : Parameter values for the HDTV standards for production and international programme exchange". www.itu.int. Retrieved 2021-02-02.
{{cite web}}: no-break space character in|title=at position 7 (help) - ^ a b "BT.1886 : Reference electro-optical transfer function for flat panel displays used in HDTV studio production". www.itu.int. Retrieved 2021-02-02.
{{cite web}}: no-break space character in|title=at position 8 (help) - ^ "BT.601 : Studio encoding parameters of digital television for standard 4:3 and wide screen 16:9 aspect ratios". www.itu.int. Retrieved 2021-02-02.
{{cite web}}: no-break space character in|title=at position 7 (help) - ^ "BT.2020 : Parameter values for ultra-high definition television systems for production and international programme exchange". www.itu.int. Retrieved 2021-02-02.
{{cite web}}: no-break space character in|title=at position 8 (help) - ^ "IEC 61966-2-1:1999 | IEC Webstore". webstore.iec.ch. Retrieved 2021-02-02.
- ^ "An Introduction to Dolby Vision" (PDF). Retrieved 2 February 2021.
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