Color Space Monitoring and Output Questions?

[Robert Houllahan]

What Sony CRT and how was it calibrated?

-Rob-

Robert Houllahan
Director / Colorist
Cinelab Inc.
http://www.cinelab.com

MAHC-PRO 6-Core 3X GTX285 20Tb SAS Wave Panel Panny 11UK SDI Plasma.

[Robert Houllahan]

Assuming you have a CRT calibrated to Rec709 you do not need to add another output LUT. Are you adding the LogC to 709 to individual clips on the timeline or as an overall?

-Rob-

Robert Houllahan
Director / Colorist
Cinelab Inc.
http://www.cinelab.com

MAHC-PRO 6-Core 3X GTX285 20Tb SAS Wave Panel Panny 11UK SDI Plasma.

[Jamal Howard]

It’s a Sony PVM L5 CRT. Calabrated using color bars (All I have access to at the moment).

Right now I’m adding the LUT as a node to individual clips as I have a mix of RED and ProRes footage in this timeline.

As I mentioned in my earlier post, the LUT I generated on the Arri website has no color conversion on it (1D “none”, not Rec709 3D) as I read recommended by Mike Most in other posts. Is that correct?

[Joseph Owens]

[Jamal Howard] ” Calabrated [sic] using color bars (All I have access to at the moment).”

“Sort of lined up” is what you get using color bars as a reference. Calibrated, not so much, and I’d be surprised if a LUT made any difference under these circumstances.

You’ve been working in 709 all along, and otherwise the whole idea of a LUT is a waste of time and processing cycles. BluRay? fine. Automatic Quicktime gamma conversion in Compressor? Also, pretty much okay.

Maybe I’ve been at this for too long, but I just don’t “get” this multiple layers of LUTs.
In a sense, every correction is a LUT. Unless you are traversing media with entirely different primary stimulus emitters, LUTs are not necessary.

jPo

You mean “Old Ben”? Ben Kenobi?

[Jamal Howard]

Thanks for the thoughts.

So does that mean I don’t need the Arri LUT to grade/view the REDLogFilm files?

So just do the grade from the (very) flat REDLogFilm gamma?
And if that’s the case, why has it been recommended to use a LUT on the REDLogFilm files?

[Mikhail Puzyrev]

When I grade for tv or DVD destination I never use any log colorspace. Rec 709 colorspace and 709 or redgamma2 gamma curve. Otherwise it’s a waste of time.

[Omar Godinez]

Joseph,

You and I have have pretty much the same experience. I agree with you, for me, every correction is a LUT.

I prefer to start with Alexa LogC or REDlog Film in Node 1 with a Primary Custom LUM S-Curve or an aggressive Primary Contrast correction. That, for me, is my LUT. Then, I go into grading.

Omar Godinez
Colour Cafe, LLC
Dallas, TX

MacPro5,1 2.93GHz 12-Cores
24GB RAM
GTX-470 (x2)
RED Rocket
FSI LM-2461W
BMD UltraScope
Panasonic 12 Series Pro Plasma

[Mike Most]

Its not a waste of time if you use it correctly. Using Redlogfilm as the gamma curve allows full retention of virtually all information in the original RAW record. If you use a proper processing pipeline, it also yields what is arguably the best greyscale interpretation of Red material that has ever been available, superior to and more controllable than either Redgamma or Redgamma2. How to do that most effectively has already been discussed in numerous threads here and elsewhere.

[Nook Kim]

I think Jamal is also asking about using LUT for previewing in another color space (or gamut, sRGB in this case) than the primary delivery format (Rec 709 in this case). IMHO, this is very important practice to have extra preview monitor(s) for different color spaces unless I’m allowed or paid to perform multiple rounds of grading just for any additional delivery formats.

Just for this purpose, our team is preparing a color management pipeline which includes top-of-the-line hardware and softwares. Our aim is to be able to match all in-house monitors as close as possible and to generate and utilize color space conversion LUT’s.

As for the use of LUT in Resolve for Red material, I also grade in Redcolor2/Redlogfilm with Arri Log to Rec709 3D LUT as input LUT at the project level. It is no doubt that Redlogfilm offers much more useful range than any other gamma space Red has to offer in grading environment. Very rarely, I do grade without the LUT if I feel like the LUT is limiting the range of the footage. However, I can’t argue with how effective it is to use the LUT since it really speeds me up.

Nook Kim
http://www.nookkim.com

[Mike Most]

You should not be using a LogC to Rec709 LUT as built on the Arri site as that would include an Alexa-specific color matrix. You should build a LUT to go from LogC to Video without the matrix. That yields a great result when used behind Red footage that’s interpreted using either Redcolor or Redcolor2 (those are color matrices) and RedlogFilm. You don’t want to be using another color matrix as that will yield extreme saturation and incorrect colors. Further, you should not be using the LUT as an input LUT as that will limit information, especially if the image is underexposed or overexposed. You should have the LUT downstream in the processing path, at least after an initial correction, to allow for exposure adjustments prior to the LUT. All LUTs are designed to convert from one color space to another based on a proper exposure. If the material is not properly exposed, the LUT cannot do its job. You can fix that limitation by using the LUT after an initial correction, either on the first node, a later node, or on the output.