A few distinct concepts may have become conflated in these slides from the presentation “Practical HDR and Wide Color Techniques in Gran Turismo SPORT” [1], particularly color gamut, OETF/EOTF transfer functions, and the standards used in different applications. The presentation correctly introduces OETF and EOTF as separate stages of the imaging pipeline, but the subsequent slides appear to blur the distinction between them and additionally conflate sRGB, BT.709, and BT.1886. Here are the specific points I would suggest revisiting.
This slide appears to combine television standards, PC monitor standards, and different transfer functions in a way that may confuse the reader:
“sRGB Gamma (OETF)”
The slide is incorrectly labeled. It appears to be mistaking the BT.1886 EOTF for the sRGB OETF.
“Almost all of SDR TV and PC monitors use this.”
The display side of the imaging chain is described by an EOTF, not an OETF. SDR TVs generally target a power-law gamma around 2.2-2.4, not the piecewise sRGB curve. Likewise, while sRGB is the de facto color space standard for the web and PCs, many PC displays pair sRGB with a ~2.2 display gamma.
“Check ITU-R BT.1886 for more detail.”
sRGB was created by Microsoft and Hewlett-Packard for web browsers and computer screens viewed in bright offices. BT.1886 is a reference EOTF for flat-panel HDTV displays used in studio production. Therefore, the slide should not direct the reader to BT.1886 as though it were the specification for sRGB.
The first equation is the BT.709 OETF, which maps a scene-referred linear-light quantity into a nonlinear video signal. It is not the BT.1886 EOTF, which maps an encoded video signal to display luminance. BT.709 OETF ≠ BT.1886 EOTF.
“Gamma” is an imprecise term for both BT.709 and sRGB. Both are piecewise transfer functions rather than simple power laws. “sRGB transfer function” and “BT.709 OETF” are more precise descriptions.
“sRGB Gamut • “ITU-R Recommendation BT.709” = Rec.709 = BT.1886 =sRGB • Different names, same gamut • sRGB 100 nit is our standard of SDR.”
BT.1886 defines a reference EOTF, not a color gamut. Equating a gamut/colorimetry standard directly with an EOTF standard in a flat equation is sloppy engineering notation.
BT.1886 does not define RGB primary chromaticities or a reference white point. Those parameters are defined by the associated standard, such as ITU-R BT.709.
- Hajime UCHIMURA, Kentaro SUZUKI, “Practical HDR and Wide Color Techniques in Gran Turismo SPORT,” SIGGRAPH ASIA 2018, Polyphony Digital Inc.
The Daejeon Chronicles 
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