Converting a log colour space to linear using ffmpeg

Question

I'm making some viewing files of some neg film scans. The film scans are converted to FFV1.mkv using rawcooked and then I have an ffmpeg recipe to create the viewing files.

I have managed to convert from neg to pos, but would also like to change the colour space from log to lin so the viewing files are a bit easier to watch.

Is this possible in ffmpeg?

My recipe so far :

for %%a in ("*.mkv") do ffmpeg -i "%%a" -i .\THE_LOGO.png -c:v libx264 -crf 23 -maxrate 5M -bufsize 2M -c:a aac -b:a 192k -filter_complex "yadif, format=yuv420p, negate, [1]scale2ref=w=oh*mdar:h=ih*0.17[logo][video];[video][logo]overlay=290:48, drawtext='fontfile=c\:/Windows/Fonts/Arial.ttf': timecode='00\:00\:00\:00': r=25: x=(w-tw)/2: y=h-(2.2*lh) :fontsize=100 :fontcolor=white: box=1: boxcolor=black: boxborderw=7" -y "%%~na_BITC.mp4"

Many thanks :-)

Answer 1

I have managed to create a working recipe using curves - whilst not strictly a log to lin lut, it gives a more watchable output.

for %%a in ("*.mkv") do ffmpeg -i "%%a" -i .\THE_LOGO.png -c:v libx264 -crf 23 -maxrate 10M -bufsize 2M -c:a aac -b:a 192k -filter_complex "yadif, format=yuv420p, curves=all='0/0 0.5/0.75 1/1', curves=increase_contrast, negate, [1]scale2ref=w=oh*mdar:h=ih*0.17[logo][video];[video][logo]overlay=100:100, drawtext='fontfile=c\:/Windows/Fonts/Arial.ttf': timecode='00\:00\:00\:00': r=25: x=(w-tw)/2: y=h-(2.2*lh) :fontsize=150 :fontcolor=white: box=1: boxcolor=black: boxborderw=7" -color_primaries bt709 -color_trc bt709 -colorspace bt709 -y "%%~na_BITC.mp4"