AVS Softlight

Argaricolm · 3rd June 2024, 23:33

Anyone knows something about OETF and EOTF functions?
The interesting thing here for me is:
From their description in docs I'v found that OETF is used to encode original light and EOTF is reverse.
So first I thought that if I use EOTF on data I will get "original lightness of the scene". But EOFT function makes everything MUCH darker. And OETF makes brighter. It can't be that original scene lightness was so dark.
Or it is just a misunderstanding because of "light" differs from "electric signal" - so this functions are not designed to be used such way (maybe they are designed to be used only inside camera and inside display hardware).
But then it is strange that OETF function gives great results on some content.
For example Divergent 2 and 3 blurays processed by it (Rec.709 limited -> full range -> OETF) results it bright picture but with good contrast. While I'v tested on other BDs and result are just bright picture with lost contrast (its possible to get better contrast if limited -> full conversion is used twice before OETF, but this burns a lot of darks). So it looks like for some content there should be another OETF function. But same OETF is specified for Rec 601 and Rec 709.

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3rd June 2024, 23:33	#20 \| Link
Argaricolm Registered User Join Date: Apr 2018 Posts: 51	Anyone knows something about OETF and EOTF functions? The interesting thing here for me is: From their description in docs I'v found that OETF is used to encode original light and EOTF is reverse. So first I thought that if I use EOTF on data I will get "original lightness of the scene". But EOFT function makes everything MUCH darker. And OETF makes brighter. It can't be that original scene lightness was so dark. Or it is just a misunderstanding because of "light" differs from "electric signal" - so this functions are not designed to be used such way (maybe they are designed to be used only inside camera and inside display hardware). But then it is strange that OETF function gives great results on some content. For example Divergent 2 and 3 blurays processed by it (Rec.709 limited -> full range -> OETF) results it bright picture but with good contrast. While I'v tested on other BDs and result are just bright picture with lost contrast (its possible to get better contrast if limited -> full conversion is used twice before OETF, but this burns a lot of darks). So it looks like for some content there should be another OETF function. But same OETF is specified for Rec 601 and Rec 709.