Transfer functions in imaging: Difference between revisions

Revision as of 05:39, 2 February 2021

Revision as of 05:57, 2 February 2021

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== Definition ==

The '''opto-electronic transfer function''' ('''OETF''') is the [[Transfer function|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]].<ref name=":0">{{Cite web|title=BT.2100  :  Image parameter values for high dynamic range television for use in production and international programme exchange|url=https://www.itu.int/rec/R-REC-BT.2100-2-201807-I/en|access-date=2021-02-02|website=www.itu.int}}</ref>

The '''electro-optical transfer function''' ('''EOTF''') is the [[Transfer function|tranfer function]] having the picture or video signal as input and converting it into the linear light output of the display.<ref name=":0" /> This is done within the display device.

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=== [[Gamma correction|Gamma]] ===

* [[Rec. 601]], [[Rec. 709]] and [[Rec. 2020]]: The [[ITU-R]] '''recommendations BT.601, BT.709 and BT.2020''' describe the reference OETF of respectively [[Standard-definition television|SD-TV]]<ref name=":3" />, [[High-definition television|HD-TV]]<ref name=":1" /> and [[Ultra-high-definition television|UHD-TV]]<ref name=":4" />. They are identical OETF based on a [[gamma curve]] and used for [[Standard-dynamic-range video|SDR-TV]].<ref name=":3">{{Cite web|title=BT.601  :  Studio encoding parameters of digital television for standard 4:3 and wide screen 16:9 aspect ratios|url=https://www.itu.int/rec/R-REC-BT.601/en|access-date=2021-02-02|website=www.itu.int}}</ref><ref name=":1">{{Cite web|title=BT.709  :  Parameter values for the HDTV standards for production and international programme exchange|url=https://www.itu.int/rec/R-REC-BT.709/en|access-date=2021-02-02|website=www.itu.int}}</ref><ref name=":4">{{Cite web|title=BT.2020  :  Parameter values for ultra-high definition television systems for production and international programme exchange|url=https://www.itu.int/rec/R-REC-BT.2020/en|access-date=2021-02-02|website=www.itu.int}}</ref>

* [[Rec. 1886]]: The '''ITU-R Recommendation BT.1886''' is the reference EOTF of [[Standard-dynamic-range video|Standard Dynamic Range TV (SDR)]].<ref name=":2">{{Cite web|title=BT.1886  :  Reference electro-optical transfer function for flat panel displays used in HDTV studio production|url=https://www.itu.int/rec/R-REC-BT.1886/en|access-date=2021-02-02|website=www.itu.int}}</ref>

* [[sRGB]]''': sRGB''' defines a transfer function based on a gamma curve and used for monitors, printers, and the [[World Wide Web|Web]]. It is standardized as '''IEC 61966-2-1:1999'''<ref>{{Cite web|title=IEC 61966-2-1:1999 {{!}} IEC Webstore|url=https://webstore.iec.ch/publication/6169|access-date=2021-02-02|website=webstore.iec.ch}}</ref>