3D LUT from LogV2 or Cinelike-D (etc.) to Rec.709 -- Clipping

IAM4UK wrote on 7/8/2019, 1:44 PM

I have some footage from a Pixel2XL shot via FilmicPro with LogV2, and I have some footage shot on Panasonic GH4 shot with Cinelike-D. I have used LUT for each type of footage, with each LUT specific to the source and designed to translate to Rec.709.

Issue: While the colors look better and more standardized after the LUT (as hoped and expected), the Dynamic Range apparently has expanded enough to cause clipping at both ends of the histogram. If I reduce contrast, I can avoid some of the apparent crushing, but I don't really gain full Rec.709 range.

Any ideas about this? Anyone use LUT for similar purpose? Can you share your experiences/results/best practices? Thanks!

Comments

Musicvid wrote on 7/8/2019, 9:50 PM

the Dynamic Range apparently has expanded enough to cause clipping at both ends of the histogram.

Correct. Dynamic Range has been reduced by effective two bits per pixel, from 1024 levels to 256 levels per channel.

Marco. wrote on 7/9/2019, 3:33 AM

@IAM4UK
Which pixel format do you use in your project properties?

IAM4UK wrote on 7/9/2019, 8:12 AM

@IAM4UK
Which pixel format do you use in your project properties?


8-bit

Should I have that set to one of the 32-bit floating point options? If so, full or video levels? And will that have any adverse or unwanted effects on my eventual renders to 8-bit Rec.709?

 

Also: Thank you.

Marco. wrote on 7/9/2019, 8:37 AM

If you need to correct clipping introduced by a LUT you would need to use a floatpoint pixel format instead of 8 bit. I'd try video levels first, it's easier to handle.

IAM4UK wrote on 7/9/2019, 6:08 PM

If you need to correct clipping introduced by a LUT you would need to use a floatpoint pixel format instead of 8 bit. I'd try video levels first, it's easier to handle.


I experimented with the same clips and workflow, but this time used 32-bit floating point (video levels). Success...thank you!