sRGB piece-wise EOTF vs pure gamma

Discussions - ACESNext VWG – Output Transforms
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Hi Thomas and all,

It might take me a while to get caught up on 178 posts!

I stand by what I said in my email that was posted, although I am no longer Technical Secretary of IEC/TC 100/TA2. That is one of the positions I gave up as I moved into semi-retirement.

I can add a few comments before reading the posts:

  1. sRGB is for computer displays that are calibrated using a LUT in the video card, or color managed using ICC color management, so there is no need for or benefit of a pure gamma EOTF.
  2. The sRGB ICC profiles have always used the two-part EOTF.
  3. During the time CRTs were used as computer displays accuracy and uniformity were limited, but by current standards the difference between the sRGB EOTF and gamma 2.2 is large, reaching up to 9 counts in 8-bit.
  4. A lot of color encodings are called sRGB that are not really sRGB. My suggestion would be if it is not exactly sRGB don’t call it sRGB, just say what it is, e.g. 200 nit peak white gamma 2.2 EOTF 709 primaries (or whatever).
  5. In most cases SDR video displays should be calibrated to the ITU-R BT.1886 EOTF.
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