Help converting formula to RPN (LogC4 <> Linear)

[groucho86]

Hello! Is anyone able to translate to RPN/Expr ARRI's LogC4 to Linear and Linear to LogC4 formulas found here?
https://www.arri.com/resource/blob/278790/bea879ac0d041a925bed27a096ab3ec2/2022-05-arri-logc4-specification-data.pdf (page 9 under 'Reference CTL Implementation')

Thanks in advance!

[Selur]

No, not sure whether it helps, but https://www.arri.com/en/learn-help/learn-help-camera-system/tools/lut-generator has a link with a 3D LUT Package for LogC4.

[groucho86]

Thanks Selur, but a LUT cannot handle values out of 0.0-1.0 range, so it needs to be formula-based.

[Julek]

I rewrote the example on page 10 to Expr here: https://gist.github.com/dnjulek/58a252948adbe63fd4929fd9ce151eca

[groucho86]

I rewrote the example on page 10 to Expr here: https://gist.github.com/dnjulek/58a252948adbe63fd4929fd9ce151eca

Much appreciated Julek! Will compare against Resolve's implementation asap.