Hı everybody,

I'm a newbee wıth DS nİtris and I'm trying to find the best workflow in this situation:

I have to color correct a movie shot in HD with the F23 camera. Dop choose to use the S-log gamma mode. That's the first time İ work like that as I am a colorist more familiar wıth 35mm negative worflow in a DI environnement where you only deal with log files.

-1st question: does the S-log mode delivers a real log file ?

As far as I understood, Nitris manage only Linear files. So, if my original files are Log, should I use the LogtoLin conversion in Nitris?

- Then, when output to the Arri, should İ use Linear or Lin to log ?

- Does Nitris accept 3dLut ?

My files are 4:4:4 and we need to watch with different display so we convert everything in 4:2:2. Does it change anything to the final DPX files ?

Basically, İ think İ have to choose between 2 workflow:

-Linear. We consider the f23 footage as linear and İ render in linear without any Lut.

-Log. We consider the F23 footage as Log and İ have to apply a LogtoLin display Lut during the grading. Then İ render in Lin to log.

What is the best way ? Any advice warmly welcome.

Pascal

Hi Pascal, I usually link in with a Log-lin then render out with a Lin-log, this gets my files ready for digital negative. Make sure to uncheck the "clamp" button, for some reason it's on by default. DS does use 3D Luts but only certain types (look to the manual). In your sequence, there is a button to switch to "Proxy" view, this will change your sequence to a 4:2:2 HD framesize. Make sure in your output tool(under the "tape" tab), that you change the convert option to "Center Cut" otherwise the image may appear squeezed on your monitor.

Hi and thanks a lot for the infos.

Actually, I started with the full linear workflow and I'd like to make a  print test with your setups.

During the Lin-Log conversion, do you apply any Lut or do you change the gamma, gamma film or soft clips settings ?

I don't change anything except to turn off clamping. Once in DS I can either feed the timeline, viewer or monitor a different LUT if necessary, removing it on export. I generally open up the original file in Photoshop with the new outputs and check the Levels and Histogram to make sure nothing has changed. Our color work is generally sent to a Pablo or Baselight, so they want back out what went in.

Don't know if this doc will be helpful or not:

http://www.aipcinema.com/ficheiros/Conteudos/SRW_ITG_S-Log_001_IO_EN.pdf

Jef

Looks really interisting, thanks a lot Jeff.

Pascal.

Also, consult the Avid DS Hi-Res Workflow and Color Guide posted on http://aviddssupport.avid.com/index.htm?section=documentation/online_library.htm&sub=guides/10.0.htm.

It offers some information on file based workflows and how to deal with look up tables.

Plus, since you work in 4:4;4, be aware that DS 10.x will not automatically convert gamma and color information if you perform your color corrections in 4:2:2.  You should work in 4:4:4 for that part of the process to keep the integrity of your results.

Read the guide and check the online help too for all details.

Thank you Sylvain. By the way, I'm working with version 8.0.

About 4:4:4...actually I work in 4:2:2 since it was not possible to get a proper display in 4:4:4. When I asked the in house technician to set up the output display in 4:2:2, they told me that the only solution was to open a new project in 4:2:2. Nobody told me about any proxies.

I let the facility's technician opened a new 4:2:2 project and asked him to make sure we will be able to aplly the cc setup to the original 4:4:4 at the end of the project. Is there anything wrong with that ?

Since you are using version 8, ignore my comment that only applies to version 10 and higher.

In version 10, engineering implemented the correct color methodology with respective gamma settings for HD RGB and Hi-Resolution formats.  In version 8, everything is treated as YCbCr so there are basically no difference between 4:2:2 and 4:4:4 results.  No at all so in version 10...

Do you mean that the YCbCr treatment will remove any difference between 4:2:2 and 4:4:4 in terms of resolution ?

İ am at a stage where İ am asking if printing directly from the 4:2:2 files will give the same result than the 4:4:4 on the print.

4:2:2 is compression on the color channels.  It cannot be the same as 4:4:4 where all color channels are uncompressed.  So, no, 4:2:2 cannot be identical as 4:4:4 but to be honest, and depending on your images, many people might not even see a difference.  But an expert eye can...

Yeah, the print test İ saw today showed a VERY little difference between both.

İn the Avid DS workflow color guide, ı read something about a printing density sequence lut but couldn t find it in Nitris 8.0. İs it something only for version 10.x ?

Yes, high-resolution color management and a wide variety of LUTs support was implemented in version 10 and above.