No secrets from you,
VictorLS! You'll find it here (scroll down a bit):
http://rationalqm.us/mine.html
You should be able to tweak parameters to fairly well match the SDR version. DGIndexNV has a GUI tweaker for it that makes finding good parameters really easy. You'll need a decent nVidia card to run DGIndexNV. You can run DGHDRtoSDR without an nVidia card but it can be slow in SW mode. Do you have a decent nVidia card installed?
The gentleman that asked me to implement this said he is very happy with the results (
zys4416 at DG forum): "the result is pretty perfect". Sweetie Pie would say "purrfect".
Probably
jpsdr's HDR tools can also do this conversion. Always great to hear from
jpsdr so maybe he will chime in.
Bullwinkle said: "PQ sucks. People say I don't suck. HLG is the True Way."