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Compensate for Scene-referred Profiles - Do you use this?

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Shawn MarshallCompensate for Scene-referred Profiles - Do you use this?
by on Oct 1, 2012 at 8:02:57 pm

I've read Trish Meyer's piece on what this color management setting is supposed to do, and I sort of understand it, but I find it a real hassle to implement because whenever I've tried to generate a RAM preview with Compensate for Scene-referred Profiles enabled the resulting RAM preview just stutters along at 3 or 4 fps on my 2012 Mac Pro.

My monitor is calibrated to the sRGB color space. Most of our work involves 3D animations rendered in Cinema 4D or working with storyboards provided by agencies. In such cases I usually set up my color management workspace in AE CS6 for 16-bit depth, sRGB IEC61966-2.1 working space. I assume these are the correct settings if the project is destined to be viewed primarily on computers.

But what if it's going to play on HDTV monitors at trade shows or for a broadcast TV commercial or show? In such cases I would change the working space to HDTV (Rec. 709). But then my 3D renders and PSD elements look washed out. Sometimes.

And this doesn't even address what happens when I compress a color managed Pro Res 4444 Quicktime master to an h.264 Quicktime or mp4.

Can anyone offer some clarity about the correct workflow?

Thanks.

Shawn Marshall
Marshall Arts Motion Graphics


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Walter SoykaRe: Compensate for Scene-referred Profiles - Do you use this?
by on Oct 2, 2012 at 1:54:53 am

[Shawn Marshall] "I've read Trish Meyer's piece on what this color management setting is supposed to do, and I sort of understand it, but I find it a real hassle to implement because whenever I've tried to generate a RAM preview with Compensate for Scene-referred Profiles enabled the resulting RAM preview just stutters along at 3 or 4 fps on my 2012 Mac Pro."

There's some additional explanation for the Compensate for scene-referred Profiles feature under Gamma and Tone [link] in the documentation. Andrew Somers has written a great post here [link] including some information on the difference between scene-related and display-related profiles. I do leave it on when using color managed workflows.

With regard to the low fps, are you previewing your work on a profiled computer monitor via the graphics card, or a calibrated monitor via a video IO card?


[Shawn Marshall] "My monitor is calibrated to the sRGB color space. Most of our work involves 3D animations rendered in Cinema 4D or working with storyboards provided by agencies. In such cases I usually set up my color management workspace in AE CS6 for 16-bit depth, sRGB IEC61966-2.1 working space. I assume these are the correct settings if the project is destined to be viewed primarily on computers. But what if it's going to play on HDTV monitors at trade shows or for a broadcast TV commercial or show? In such cases I would change the working space to HDTV (Rec. 709). But then my 3D renders and PSD elements look washed out. Sometimes. "

If color management is not enabled, then Ae makes no effort to ensure accuracy or consistency. RGB values are simply passed through as in any other unmanaged workflow.

If color management is enabled, then Ae interprets a footage item according to its embedded profile (or the profile defined by the user in Interpret Footage), transforms it to the working space where all calculations are performed, then optionally transforms it again to the monitor's profile for display or to the output module's color management space for render. This preserves the appearance of colors throughout the Ae workflow.

The working space is the one common space into which all source colors are transformed for calculations (effects and blending), but it can be separate from the source and output spaces.

With that in mind, imagine a source image with no applied effects or blends. If the working and display/output spaces are large enough, we can preserve the look of the original image from its source through the working space to the display and output spaces. Changing working spaces will not change the visual result (again, unless we choose a working space smaller than the output) because we are simply transforming the same perceived color through a series of different RGB representations in different color spaces.

Once we apply some effects or blends to the image that alter the image, changing the working space will change the visualresult. Why? Because these effects and blends are really just math done on the RGB values for the pixels, not the colors those RGB values represent, and because different color spaces translate specific RGB values to actual perceived color differently.

Theoretically, there's no right or wrong choice for working space (again with the proviso that it is large enough), because adjustments like these are made subjectively. If you were working in a different working space, you'd simply have to make different adjustments to get your same desired end result. You should not change working spaces in the middle of a project because it could break the appearance of your subjective color decisions.

As for C4D imagery being washed out, R13 renders linearly. If you turn off color management or incorrectly interpret the source footage, linear images won't look right.


[Shawn Marshall] "Can anyone offer some clarity about the correct workflow?"

Practically speaking, if you have a single deliverable, I think it's a good practice to base your working space on your deliverable as Ae bases the default output module profiles on the working space.

If you have multiple deliverables from the same project, you can use the output module's color management tab to correctly manage for multiple color spaces.


[Shawn Marshall] "And this doesn't even address what happens when I compress a color managed Pro Res 4444 Quicktime master to an h.264 Quicktime or mp4."

Yeah, that's where all hell breaks loose. Unless you control the final display system, you obviously can't count on color management all the way though.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
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Shawn MarshallRe: Compensate for Scene-referred Profiles - Do you use this?
by on Oct 3, 2012 at 8:11:40 am

Thanks for the reply. I have been working in color managed workspaces for six or seven years. It's the addition of this Compensate function a while back which is a bit of a mystery. I'll read up on it some more.

I just rely on my calibrated monitor to keep track of my colors. I have an NTSC monitor hooked up to an AJA box which I haven't needed for years.

I've never been able to get a RAM preview to play real time when Compensate for Scene-referred Profiles is enabled. They play fine when it's off, 3 fps or so when it's on. This has happened over multiple versions of AE, over multiple workstations (2008, 2012 Mac Pros) and multiple operating systems (Leopard, Snow Leopard, Lion). Given this issue I'll probably just leave the feature deactivated.

Cheers.

Shawn Marshall
Marshall Arts Motion Graphics


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