> On Jul 6, 2015, at 1:55 PM, Deke Kincaid <[email protected]> wrote: > > Just a note to add to Matt's post. Do not use the ACES or IIF included with > Nuke as it is 3 years old (ACES v0.1.1). Get the ACES 1.0 OCIO profile off > the Academy site (it links to HP's current fork of the OCIO configs on > github). > > http://www.oscars.org/science-technology/sci-tech-projects/aces#field-tabbed-content-tab-1 > > <http://www.oscars.org/science-technology/sci-tech-projects/aces#field-tabbed-content-tab-1> > > That should be it. One possible hitch -- I think the EXR writer doesn't know > that you're in ACES so won't write the metadata about ACES. (Anybody know if > that's still the case?) > > Nuke does not support writing the "chromaticities" metadata at the moment and > you can't simply use a modifyMetadata to add it as it's not a simple string. > Also we do not yet support the ACESClip sidecar file at this moment either. > > -- > Deke Kincaid > Media & Entertainment OEM Development Manager > The Foundry > Skype: dekekincaid > Tel: (310) 399 4555 - Mobile: (310) 883 4313 > Web: www.thefoundry.co.uk <http://www.thefoundry.co.uk/> > Email: [email protected] <mailto:[email protected]> > > On Mon, Jul 6, 2015 at 1:27 AM, <[email protected] > <mailto:[email protected]>> wrote: > Hey Matt, > > I have to test some of those things and will get back to you. Or hopefully > not. :) > This is just a quick Thank You for your thorough explanation. > > Greets, > Igor > > > > Am 05.07.2015 10:05, schrieb Matt Plec: > On Fri, Jul 3, 2015 at 10:04 PM, <[email protected] > <mailto:[email protected]>> wrote: > > Hey guys, > > I am trying to wrap my head around ACES. > > I'm sure you're not the only one. I have heard that before... Here's > the basic idea: > > First off, for anyone who hasn't thought much about color management > in general, why does it matter? > > When you work with color in the computer it's just numbers, so we need > a way to define what color, in some absolute way, [1.0, 0.0, 0.0] > means. > > What do you need to turn a [1.0, 0.0, 0.0] from Nuke into to see the > same color projected by a DCI compliant monitor as you see on your > workstation monitor? Or if you've got an sRGB JPEG and a REDcolor clip > does the value [1.0, 0.0, 0.0] mean the same color in the scene? (No!) > A colorspace specification like sRGB, rec709, AdobeRGB, and ACES > defines that. Which in turn makes it possible to transform color > values between one space and another. > > There are two key parts to a colorspace: the colorimetry -- the > primaries & white point that specify the hue/shade intended by a color > value -- and the transfer function (or encoding), which specifies how > the increase/decrease of values is encoded -- log, some gamma, etc. > > When you read an image into Nuke you might have noticed that the > (so-called) colorspace knob only defines the encoding. As a result, > there's sort of a built-in assumption that you are working in the same > colorimetry as your input images (and that they are all the same) and > all you need to specify is the transfer function to make them linear. > That was true (ish) when everything came from a film scanner and went > back out to a film printer. (err... well, let's not get into that.) > And we hack around it with Colorspace nodes. > > Luckily, by the nature of digital capture devices, their colorimetry > is known (even if only to the manufacturer) so a translation to well > known spaces can also be defined. Then as a practical matter we just > need to pick a working space to transform different sources into for > processing and back out of for display/delivery. > > In the past we knew what the "from" was based on file type, headers, > etc. (hopefully) but there was no well-defined standard "to" (though > it's essentially de facto been sRGB/rec709). > > Enter ACES. > > So, from what I understand ACES gives us on hand more gamut and on > the other hand it is a way to bring footage together from different > sources more easily. > That sounds good, right?! Ok, but I never used that kind of > workflow, and it does not seem to be that trivial. > > I think you'll be surprised. Conceptually it actually isn't really > much more than what happens now in Nuke. > > By default when you read an image in it goes through a process to > linearize it. When you write it out it goes through another process to > log or gamma it. If you're working in ACES that process just involves > more math to change the colorimetry in addition to the encoding. For > you as a user it's just more manual because of outdated assumptions > built into the Read/Write, and there are some gotchas to watch out > for. > > Since the Read & Write only do a 1D LUT for colorspace, you need to > use OCIO nodes to do the input and output colorspace transform > instead. Which means setting the Read/Write colorspace knobs to > linear. But if you do this and you're converting to/from log with > OCIOColorSpace or OCIOLogConvert then the Write can't autodetect that > you're writing log and set the dpx headers correctly, so you need to > set the transfer knob manually. > > In the Project Settings' OCIO tab, pick the ACES config and set the > viewer LUTs to use OCIO luts so you get the ACES conversion to > rec709/sRGB for display on screen. > > Congratulations, you're working in ACES. > > The scenario: > I've got R3D files which I push through hiero to generate openEXRs. > Problem I've got is I do not see an option to set the exrs for ACES, > like in REDCINE where I can specify that in the export settings. Ok, > comparing those two (redcine aces exr vs hiero exrs) the difference > is visible, most prominent the reds seem more pushed or saturated in > a non-aces exr. > > If you've selected ACES for your OCIO config, then your inputs are > converting to ACES on read and the colorimetry of the output EXRs will > be ACES since there's no conversion when writing to EXR. > > Now my questions: > When I process them as aces, I also need a display LUT so that I see > the right output, right? Is this provided with the OCIO Aces Config? > Have to take a look at that. > > Yes. > > What do I do with CG content? Do I apply a LUT in Maya, or even to > the render itself? Or do I treat it as usual and just transform the > color into ACES space? To what do I render? ACES or nonACES plate? > Do I treat CG simply as scene referred light? > > You'll need to convert your textures from whatever space they're in > now to ACES, either by converting the files or setting something on > your texture reads, like you'd do to linearize them. I don't know > about others, but MODO supports OCIO so you can pick the ACES config > and then just make sure your texture inputs have the right colorspace > set. And of course view through the ACES sRGB or rec709 LUT so the > image gets translated properly for your display. Essentially the same > as in Nuke. > > How do I export in Nuke exrs in aces? Simply set to linear and > everything is fine, or more magic sauce? > > That should be it. One possible hitch -- I think the EXR writer > doesn't know that you're in ACES so won't write the metadata about > ACES. (Anybody know if that's still the case?) The files are EXRs just > fine of course but anyone else relying on that metadata to identify > them as ACES won't find it. Maybe someone's got a ModifyMetadata node > they could share that puts the right stuff in, to chain in before the > Write? > > Hope this helped! > > I am a bit confused, and any (non-technical as possible) > explanation, tip, link, whatever is highly appreciated. > > Thanks in advance, > Igor > _______________________________________________ > Nuke-users mailing list > [email protected] > <mailto:[email protected]>, http://forums.thefoundry.co.uk/ > <http://forums.thefoundry.co.uk/> > [1] > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users > <http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> > [2] > > > > Links: > ------ > [1] http://forums.thefoundry.co.uk/ <http://forums.thefoundry.co.uk/> > [2] http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users > <http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> > > _______________________________________________ > Nuke-users mailing list > [email protected] > <mailto:[email protected]>, http://forums.thefoundry.co.uk/ > <http://forums.thefoundry.co.uk/> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users > <http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> > > _______________________________________________ > Nuke-users mailing list > [email protected] > <mailto:[email protected]>, http://forums.thefoundry.co.uk/ > <http://forums.thefoundry.co.uk/> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users > <http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
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