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 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 Email: [email protected] On Mon, Jul 6, 2015 at 1:27 AM, <[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]> 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], http://forums.thefoundry.co.uk/ >>> [1] >>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>> [2] >>> >> >> >> >> Links: >> ------ >> [1] http://forums.thefoundry.co.uk/ >> [2] 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 >> > > _______________________________________________ > 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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