Panasonic Lumix GH5 Hybrid Log Gamma

Here is the HLG to Rec709 Driftwood LUT for you all to use for FREE: https://www.dropbox.com/s/p2kqfvyz2cf...



NB Read below info for tips how to render HEVC/insert correct HDR flags etc.
New HDR Functionality recording with HLG. See the HDR video on Panasonic site at:    • Panasonic LUMIX GH5 4K HDR Video "Iso...  
Music by Nick Driftwood.

INFO:
HLG has similar gamma characteristics to SDR in dark range (processing in blacks similar to BT.709 below 100 nits), then changes to a log gamma above ~14 nits.

Extends log processing of displays high brightness peaks up to 2.5 to 3 stops to mitigate blown-out or clipped whites.

Can be displayed unprocessed on an SDR screen as EOTF adjusts system gamma to correct for viewing environment (10 to 500 nits)

Does not require scene mastered metadata unlike PQ (HDR10) or Dolby Vision.

Is best for Live production and fast turnaround HDR as you don't need to grade too much if you've exposed to use the extra display stops correctly.

To facilitate HLG production the BBC R&D will announce to broadcasters a series of licensed LUTs (Lookup Tables) implementing a range of key format conversions from;-
• BT.2100 PQ (1000 cd/m2 peak) to BT.2100 HLG
• BT.2100 PQ (4000 cd/m2 peak) to BT.2100 HLG
• BT.709 (SDR) to BT.2100 HLG (Display-referred mapping maintaining SDR "look")
• BT.709 (SDR) to BT.2100 HLG (Scene-referred mapping for matching cameras)
• BT.709 (SDR) to BT.2100 HLG (Display-referred up-conversion for SDR "look")
• BT.709 (SDR) to BT.2100 HLG (Scene-referred up-conversion for matching cameras)
• BT.2100 HLG to BT.2100 PQ (1000 cd/m2 peak)
• BT.2100 HLG to BT.709 (SDR)
Additional conversions may be added too.

These LUT variants offer support for both “narrow range” and “full range” PQ signals, as well as options that allow BT.2100 colour primaries to be used with hardware LUTs that usually assume BT.709 colour.

Driftwood and James Miller are preparing some of our own LUTs for HLG transform. You will need to at minimum have LUTs to convert Rec709 material to 2020 and vice versa if you mix a timeline's material to one or the other.

Driftwood was monitoring Rec2020 with the EZ1002B Premium UHD Televison

You Tube appear to be still working out how to handle the HEVC (with HLG flags) uploaded files. Lets see how this one above looks...

WORKFLOW:
I output on a Mac to Pro Rez 422 10-bit (you can use any 10-bit or lossless package on your computer)Iand then recoded to bring the size down and add flags using HEVC. I used FFMPEG which is freely available to Windows, Mac and Linux users to code my HEVC files and to add the necessary HLG and Rec2020 flags which will trigger HDR TVs to play automatically the content in HLG. Here's an example command line (make sure you download the 10-bit version of x265lib.

Mac users should download FFMPEG/RubyonRails/Homebrew to install a compile - Beginners help is here https://www.moncefbelyamani.com/how-t...
or here: https://github.com/fluent-ffmpeg/node...
Install X265 here http://macappstore.org/x265/

Windows Users: http://www.wikihow.com/Install-FFmpeg...

Its easier to use command line until Handbrake gets updated to use HDR flags properly.

Example FFMPEG code to generate a basic good looking HEVC file with flags:-
ffmpeg -y -i /Volume/Drive/Inputfilenamel.mov -c:v libx265 -x265-params level=5.1:vbv-bufsize=60000:vbv-maxrate=60000:crf=20 -pix_fmt yuv420p10le -preset fast -color_primaries bt2020 -colorspace bt2020_ncl -color_trc arib-std-b67 -c:a aac -b:a 128k /Volume/Drive/Export_filename.mp4