ACES red files weired

[fredjeang2]

Does somebody know why if I use ACES from open EXR generated by RCX it Works perfectly but if I use the R3D directly it's got issues: Clipped highlights. ??

[D Fuller]

Does somebody know why if I use ACES from open EXR generated by RCX it Works perfectly but if I use the R3D directly it's got issues: Clipped highlights. ??

It's hard to know without more info on your Raw settings, but I'd guess that it is because you are not interpreting the R3D as linear light, which is what ACES requires.

Here's a post by Graeme Nattress on Reduser that explains how the R3D needs to be set up to work:

The ACES starting point is linear light with scene mid grey at 0.18f. That is what we provide via the EXR output, and it's dependent on ISO as that is what decides which sensor code value maps represents mid grey and hence which sensor code value maps to 0.18f in the linear light data.

Again, just to re-iterate that we don't use an IDT because that is really only necessary for cameras that shoot something "video-ish" that needs to go through special transforms to map back to linear light and then to go through the colour space transforms. Because we take all raw development through a linear light XYZ stage (as it's necessary to do so for proper raw development) we just export that stage with an XYZ to ACES matrix (as defined by the Academy). In this sense there is no IDT.

So what we do provide is the linear light floating point data with mid grey mapped to 0.18f that does result in an a default image through the RRT and ODT that displays as accurately and as nicely as the Academy's math allows for.

That Reduser thread has a lot of good info about ACES in it. The end story is that you absolutely can set up an R3D to work with ACES in Resolve (or Nuke, or wherever) but you have to set it up in quite a specific way or your setup will defeat the ACES system. The "Use ACES" EXR export in RedCine-X is Red's way of giving users an easy way to get there without having to know the details.

[fredjeang2]

Great post. Many thanks DF.

This forum is getting more reliable in terms of
Motion  than most specialized forums.
When people know what they are talking about
It changes all.

When had this issue, I checked for imputs in the
Cow, in Lift-gamma-gain, in Red forum and there are
So many posts that finding the good ones is often
Very tedius.
The mantra generally accepted (and beleived) is that
resolve does not work properly with R3d in ACES,
And that we shouldn't use aces with native red.
And that even Red themselves don't recommend its use.
As I read this statement over and over again, I thought
It was correct.

It was not.

Again, internet is as much a source of information as
A complete desinformation one.
And there is a "mass effect" that some concepts are given for
Truth, laws or beleifs.

Thanks for the tip. Now I know it"s possible. Also interesting
The Graemme precision on IDT.

[fredjeang2]

Yesterday, also falled into a Red discution, quite
Animated and attaking Graenne and Red on the fact
That they don't bring proper LUTs for RLF like Arri
Does and because of that it's a guessing mess.

I had (and still have) a collection of cubes made by Red
Users. They work fine.
But in the end my approach is personal as it should be
And really started to build my own luts using Scratch.
In my workflow, I prefer a lut that pre-lut to 50%ish or
Let's say a "pass 1".
I like to bring the look step by step, keeping control on the dr always.

What I find horrible is this "film emulation" fashion that
Burns eveything into a high contrast fashion sauce.
The other day, I realised big mistake when grabed a
Technicolor Bond scene from Goldfinger and there was
Absolutly none clipping anywhere and the DR was there.
Actially so usable that if I applied any look flavor, the
Image stand still. Maybe one of the easiest material to
Grade and no vulgar high-contrast "film look".
So those supposed film-look luts are 99,999% crap.

I could put my hands on a 2 srips technicolor built only for LW and for what I'm seeing, I suspect
That someone grabed the settings done for
Aviator. If my memory is correct they used Scratch to build the look according to Scorcese indications. This 2 strips preserves
Integraly the image information and in this sense I think it has a good pedigree. But not
Affirming nothing as I don't know the story.

Moral of the story: as Coot says: test and veryfy.

Later on, I discovered that experienced colorists aren't
Barking on Red's lack of lut support for RLF because
They simply have their own sauce. Wich is what I
Ended to do.

Everybody started to warn me about how difficult it
Is to build reliable lut, wich is true, and stated that I
Have too little experience on that to even try it.
You know..."don't do that", "you need to be preapared"
But I never follow "well intentionned" advices that tend to limit one.
Trump can says "you're fired" because he dared.
That way, nobody can fired you.
Actually, I animate everybody to create their own sauce.


Also have a precise data sheet for creating my own luts
In Fusion. I plan to work on it the next days.

There are many many mantra and confusion everywhere.
That a Lut is a grade, that a lut has to be applied previous to a cc
And then discover colorist gurus actually not using the divine
Order in operation. The list is long.

I have only 5 years of experience in motion, and really maybe
2 years in serious. And I don't count the endless hours
Spent in internet to find the correct infos and deal with
Issues when later I discovered that it was wrong.
And the fact that a specific forum is known as "specialists"
Does not guarantee anything. Just like here in the medium format.

The wildwest is a virgen game compared to the motion mess.

[fredjeang2]

Yep: idt : none.

[D Fuller]

The mantra generally accepted (and beleived) is that
resolve does not work properly with R3d in ACES,
And that we shouldn't use aces with native red.
And that even Red themselves don't recommend its use.
As I read this statement over and over again, I thought
It was correct.

It was not.

Red has good reason to recommend the EXR path with the "Use ACES" checkbox. It is just too easy to do it wrong using the R3D method. And most users would freak out looking at linear light gamma on their histograms or scopes. One of Red's constant issues is that they'e given users an awful lot of power in their R3d system, and if you don't know some basic stuff about photography, it's very easy to get so in the weeds that it feels like everything is broken.

To their credit, Red has tried to give its users a system that conforms to known industry standards, so they don't have to re-invent stuff. RedLogFilm, for example, is designed to conform to the Cineon log you'd get from a film scan. That's a standard starting point for colorists. Red has resisted providing LUTs to transform from RedLogFilm because Cineon is a standard, so the question would be, "RLF to what?" You, the user, get to decide that one. The problem is, if you come from a video background, or are a photographer venturing into motion, you've probably never been exposed to those cinema production standards, so you're a bit on your own.

FWIW, there's a guy named Nick Shaw at Antler Post in London who has made some very good RedLogFilm to RedGamma LUTs (in various RedGamma flavors). I use them to let me deBayer to RLF but see the same thing I was seeing on set--only with the highlight retention the RLF gives. Good stuff, and pretty cheap.
---

To your other point... Yeah, misinformation has become the language of the internet. And when lots of people repeat the same crap often enough, it becomes "common knowledge". Drives me nuts. (That's why I started that other thread to try to get Michael to correct the misinformation he wrote about video color sampling. ) I don't think there's a cure for that. You just have to seek out the people who get it right most of the time and listen to them. And try to become one of them.

DAF

[fredjeang2]

Thanks Daf.

Yes, motion is highly technical and requires a lot
Of commitment. Specially when one just enters
This world and only scratched the surface (no puns
With scratch and surface)
Like it's the case for me.

Personaly, I can't give myself for satisfied when I take the easy
Way, using pre-heated workflows because the price to pay
Is generally that one does not end to understand really what he does,
Even if it works.
And knowledge is freedom. I have to learn, understand
And assimilate (...more pun...not doing it on purpose!)
How the hell is working everything to master
What I am doing and why.
This is why I ask questiins all the time.
So yes, I have often hard time to find who are the good ones
To listen to and often felt a bit on my own in a middle
Of a huge tech monster to digest.
Even Graeme is often pissed by the "established mantras"
And put a healphy limit in its interventions, when things
Start to get silly by the "I know it all".

But despite the learning curve I'm happy. I see the progress, and each time I make a step
Is very rewarding.
I've seen that the very best way while in the learning curve is forget the ego and
Don't hesitate to ask questions, no matter if the all
World see one as an ignorant.
It's better to be ignorant but learning, and I think that maybe
In internet, many people don't dare to be seen as tech deficients by others and in the end this is where the false
Knowledge comes into play. We're very exposed so the egos are active.
It took me a while to realise that even in Red forum, in the Cow,
The real knowledgeable people are a few compared to the volume of users. Bur it's just not visible at first. At first it seems that all those dudes are tech geniuses and during some
Time I felt "stupid" because I couldn't understand
Their tech conversations. Later on, I discovered that a lot are in fact posers, they know enough tech to look super pros, but...not enough to actually be pro.

Hope in the future I'll be able to be as usefull as some people
Have been to me.

Cheers from Madrid.