FLUT in Resolve

[Paul Stevenson]

Hi, apologies if I'm asking a stupid question here, but could someone explain why and when I'd use FLUT controls in post work for Red 4k footage? I'm using Resolve 15.
I shoot on Scarlet MX

Appears to boost the gain, but if so, how does that differ from increasing the ISO or exposure controls in Resolve?

Thanks!

Paul

I

 

[Bob Gundu]

It works like ISO but with finer control.

 

[Paul Stevenson]

Thanks Bob that's a big help. Are there any pros or cons to using FLUT vs ISO increases in terms of the loss in DR/ increase in noise?

 

[Michael Tiemann]

You are asking about FLUT, which is old terminology. As of IPP2, FLUT is now Exposure Adjust.

As I read the latest IPP2 Image Pipeline Stages document from RED (published 3/26/18), ISO and Exposure Adjust are part of Stage 1. Which means that Exposure Adjust and ISO are likely (and logically) conjoined into a single digital gain factor and then applied. You can easily test this: presuming you have something recorded at ISO 800 and Exposure Adjust 0, generate images in RCX from image developed with ISO 100 and Exposure Adjust +3 stops and from an image developed with ISO 6400 and Exposure Adjust -3 stops. If all three are identical (or very nearly), then you have your answer.

 

[Paul Stevenson]

Thanks for the detailed answer Michael. I'll do some tests!

Paul

 

[Mikael Lubtchansky]

+ 1.0 FLUT (aka exposure compensation with IPP2) = + 1 stop = doubling ISO value

ISO only works in 1/3 increments so equivalent to 0.3333 FLUT steps.

like Bob and Michael said : use it if you need finer ISO control or prefer using decimal values versus the ISO concept.

 

[Marc Wielage]

I have never bothered to use FLUT in final color correction on R3D files -- I just get the ISO more or less in line with what the DP did on set, along with the exposure and color temperature controls, and then do all the fine tuning with the other color-correction controls within the software. We can get far more precise with those knobs than we can with the Raw controls.

The reality of post is that we're generally under the gun to get a certain amount of material color-timed every day, and the Raw controls are much too slow for this. Also, a lot of the work we do (or at least what I do) involves setting exposure differently for different parts of the shot with tracking masks and windows, basically "burning and dodging" in the darkroom or Photoshop. So overall corrections don't hack it -- we have to correct faces, bodies, background walls, foreground objects, skies, and so on all separately. I have had shows with a dozen simultaneous windows going on, and I've seen commercial people easily do double that (particularly in fashion or music video projects).

What is true is that on the larger panels, it's easier to adjust some of the Raw controls with physical knobs, and that does help to a point. Patrick Inhofer over on MixingLight.com did a piece a year or two back where he compared Raw adjustments with normal lift/gamma/gain adjustments, and the upshot was that the final pictures were essentially identical. You do need to optimize the Raw settings, and ISO is pretty critical, though once in a blue moon I can coax a tiny bit more highlight detail from the picture by dropping it about a stop more than the original exposure and using other controls to bring everything else back up.