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simonfarussell

Linear workflow in AE

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Hey,

 

So I'm doing some compositing (AE CC 2014) and I'm wondering about how AE deals with Linear working space.
I'm finding my shape layer gradients look very different in the options box than they do on the screen. There seems to be a massive amount of sensativity down near the low ranges of colour values and then an exponential lessening of effect.

 

I'm exporting out of Cinema 4D, rendering in Linear, using PSD files in 16bit and AE is in 16Bit Linear mode too.

 

Have I forgotten to click something or is this behaviour to be expected?

 

Thanks

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Do you mean in AE, between the color picker and the viewer, they look different? Make sure you have "Use Display Color Management" checked in the View menu. That should make things match up.

 

The range of value in linear mode is like what you described. It starts getting lighter very quick and there is a large falloff to white.

 

Also, one benefit of working in linear color mode is that you can render white values above 1. If you have any areas of your render that should be above 1, you should render to 32bit files that support that like .exr. 16 bit and 32bit .psd's will clip bright values to 1. Your AE comp should be set to 32bpc too.

Edited by theta

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Here's an example of the gradient. You can see the discrepancy between what's on the screen and what's on the gradient tool colour picker. (Big version here: http://i.imgur.com/udaXqYn.jpg)

udaXqYnl.jpg

 

I'll have to double check this but I'm finding that some passes (such as GI) have the information compressed into a very small range of the spectrum... eg. You can barely see the gi pass as it's so dark.

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Yeah, ya know what? I think it's because the Gradient Editor window isn't displaying the colors in linear color, but the viewer is - so it looks lighter. Maybe it's an issue with the Gradient Editor in shaper layers not supporting linear color mode? If you add just a regular fill, instead of Gradient Fill, you can see the difference. That's really wierd.

 

If you add something like a Sapphire Gradient though the color picker matches, might just be an issue with the gradient editor.

Edited by theta

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If you keep your settings the same and turn off "Use Display Color Management", the viewer gets darker, and should match your color picker. So that tells me there's an issue with the shape layer - gradient editor not displaying the right values in linear color mode.

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If you keep your settings the same and turn off "Use Display Color Management", the viewer gets darker, and should match your color picker. So that tells me there's an issue with the shape layer - gradient editor not displaying the right values in linear color mode.

 

Thanks. It's no great shakes about the gradient not displaying properly but I just wanted to check.

It's weird, I always work in Linear but the way the values are working just feels a bit weird. I'm probably loosing it! :)

I am working on a new MP and new version of AE.

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Did you linearise your colour space, in the AE project settings? You need to (I think!) to get the correct blending in AE, but it does push the colour picker values into high gear like you've noticed.

 

Agree though that you should be rendering 32bit, 16 still clips your range between 0-1 and limits how hard you can push the colour range, it's like all the hassle of LWF with none of the benefits.

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Did you linearise your colour space, in the AE project settings? You need to (I think!) to get the correct blending in AE, but it does push the colour picker values into high gear like you've noticed.

 

Agree though that you should be rendering 32bit, 16 still clips your range between 0-1 and limits how hard you can push the colour range, it's like all the hassle of LWF with none of the benefits.

 

Yeah I've Linearised my AE settings.

Working in 32Bit may be tricky, I'm working on 6400x1080 so multipass files are pretty heavy and I'm fast running out of space. I think I'd need a new drive!

Does AE run noticeably slower in 32bit?

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CC2014 is better I think at flicking through .exr sequences, and they're not massive files. But yep, it's slower.

 

With big comps I've taken to rendering in 32 bit and then making a 16-bit project in AE - you get all that juicy colour range from the renders but AE behaves like you expect it to.

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Yeah, I guess if you wanted to, you could pick and choose only certain shots or scenes to comp in 32bpc and pre-render those out. I guess it depends on what the project is, but shots with a lot of depth of field / motion blur. Not all projects even warrant a linear workflow.

Edited by theta

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If you're working in a linearized color space and want to input gamma encoded sRGB values you can apply the “Color Profile Converter” effect to solids, text and shape layers. If you set the Input Profile to sRGB, it will convert the gamma encoded colors to linear color values and it will match up visually. AE can’t guess if you want to input color values in a linearized scene-referred space or in a gamma encoded space.

Edited by Sen

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If you're working in a linearized color space and want to input gamma encoded sRGB values you can apply the “Color Profile Converter” effect to solids, text and shape layers. If you set the Input Profile to sRGB, it will convert the gamma encoded colors to linear color values and it will match up visually. AE can’t guess if you want to input color values in a linearized scene-referred space or in a gamma encoded space.

 

I love this place! Getting the color I want when working in linear mode has always driven me nuts. I'm so glad I found out about this! Thanks, Sen!

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If you're working in a linearized color space and want to input gamma encoded sRGB values you can apply the “Color Profile Converter” effect to solids, text and shape layers. If you set the Input Profile to sRGB, it will convert the gamma encoded colors to linear color values and it will match up visually. AE can’t guess if you want to input color values in a linearized scene-referred space or in a gamma encoded space.

 

Thanks Sen. That's a useful tip.

 

I've been doing a bit of reading up as I'm not too clued up on this area. I didn't realise 32bit gave so much more range in blurs and comping. This gives quite a nice simple intro into linear in AE for anyone who's interested.

 

There doesn't seem to be a good workaround to the fact that linear in AE messes up all the responses to curves/levels/colours etc. It's frustrating as if you just want to put an S contrast curve on you can't... or you can but you have to convert the colourspace (Levels/Color Profile Converter) apply the effect and then switch back.

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There doesn't seem to be a good workaround to the fact that linear in AE messes up all the responses to curves/levels/colours etc. It's frustrating as if you just want to put an S contrast curve on you can't... or you can but you have to convert the colourspace (Levels/Color Profile Converter) apply the effect and then switch back.

 

I agree but it's not that AE messes up. Some tools are expecting a perceptual, gamma encoded color space. Best way as you describe is to sandwich the effects between color profile converters and convert from linear to sRGB/log and go back to linear. Inverting an image and adding grain are also two examples that are nicer in a gamma encoded space (log).

 

http://prolost.com/blog/2006/6/4/know-when-to-log-em-know-when-to-lin-em.html

 

Alternatively, you can convert between gamma/color spaces with Fnordware OpenColorIO or QuarterLight NuclearLUT. Gamma 2.2 is not 100% equal to sRGB. The gamma 2.2 curve approaches black at a lower angle than the sRGB spec so there's some slight crushing of the blacks.

Edited by Sen

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Alternatively, you can convert between gamma/color spaces with Fnordware OpenColorIO or QuarterLight NuclearLUT. Gamma 2.2 is not 100% equal to sRGB. The gamma 2.2 curve approaches black at a lower angle than the sRGB spec so there's some slight crushing of the blacks.

 

Oh no, we have Log as well as Linear and sRGB! They're multiplying!

 

From a brief look OpenColorIO and NuclearLUT seem to be similar but more sophisticated versions of the AE Color Profile Converter, is this right?

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From a brief look OpenColorIO and NuclearLUT seem to be similar but more sophisticated versions of the AE Color Profile Converter, is this right?

 

Color management (which the Color Profile Converter is part of) in AE is based on ICC profiles. This is a somewhat different setup to most other VFX packages that are based on a 1D LUT (similar to a curves effect) or a 3D LUT to do their color transformations.

 

OpenColorIO is going to be the upcoming opensource standard. The main advantage is that it will work identically between programs (ex. Nuke) and your color transformations will look the same regardless of the program used.

 

NuclearLUT is 1D LUT converter and provides a lot more transformations than the Color Profile Converter. I'm actually working with Sony F55 footage right now in Slog2 which is available in NuclearLUT.

 

You can do a complete manual color management workflow in AE: always enable "preserve RGB" on in- and output files, pre comp the footage and convert to linear with one of the plug-ins. Disable 'Use display color management' under View and add a guide layer with a linear to sRGB transform. This is like the old eLin days in 2004 when there was no 32bit in AE but it's still a valid workflow and it can clarify what AE is doing under the hood.

Edited by Sen

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Ah cool, this all sorta makes sense. Useful information.
I'm just going between C4D and AE so don't have to worry too much about pipeline issues.

 

I'm finding just using the built in AE converter fine for getting the response I want out of curves/levels and so on.

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Its a shame it doesn't work a bit more like nuke where everything is converted to linear behind the scenes. While we're on the subject, anyone know if you can render straight to adobe media encoder (h264) from a 32bit comp? Currently the h264 seems to come out in linear colour space (ie its much darker than it should be). If i render to lossless QT and then encode that to h264 with media encoder it works fine. - Sorry to hijack the thread : )

 

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