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AE cs5.5 color management 5D Mark II issue

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javier gonzalez
AE cs5.5 color management 5D Mark II issue
on Nov 13, 2011 at 12:57:41 am

Hi and thank you for reading this,
I am color correcting a Canon 5D Mark ii short film and i decided to use color management in AE when i noticed that i coudnt export a frame in AE and import it into photoshop looking exactly the same.
I shot my footage with SGRB color space selected in the camera. So in After effects i select Working Space - SRGB, and then the Movie Clips are interpreted as well as SRGB.
And this way i get a consistent output everywhere, great. Output is all good. But there is a problem that i cannot understand in the input. From having color management turned off to on with SRGB there is a very clear Gamma Shift in the AE Compositing window in the 5D Video Clips. Very clear and obvious.
How can this happen, is this normal?. Given that im using SRGB all around why would there be a Gamma shift within AE?
Basically when i enter AE and i see the 5D clips with color management turned off, they have a bit more saturation and contrast (in relation to the next step). If i then turn color management on, selecting working space to SRGB and allowing the clips to be interpreted as SRGB as well, then there is a clear gamma shift that reduces contrast and saturation in the clips in the AE compositing window.
To see this i only need to look at the AE compositing window, i dont need to export or do anything else.

So the question is, how can i enable color management in AE with 5D Mark ii footage without getting a gamma shift in the transition from having it off to on?

Im using Windows 7, After effects CS5.5

Thank you so much for your help and info
Jav


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Bob Dix
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 3:39:45 am

I would not use After Effects, most stills processed in Canon Digital Professional from RAW to jpeg generally need no tweeking in ADOBE'S PHOTOSHOP and in HD video 1920 x 1080p colour very never needs colour correction. My experience over 3.5 years, but, you need the exposure levels to be spot on.I use CS5 5.5.2


Good luck

And that is using a Canon 5D mark II with the latest Firmware update

Freelance Imaging & Video
AUSTRALIA


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Walter Soyka
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 5:59:33 pm

Have you calibrated and profiled your monitor? This is an important first step and will influence how color-managed documents appear on your screen.

If you're new to color management in AE, I'd suggest you start with Adobe's color management workflow white paper [link].

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
Creative Cow Forum Host: Live & Stage Events


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 6:14:03 pm

hi and thank you for the reply,
of course my monitor is calibrated properly, also i have read all the adobe whitepapers and other 50 articles online,
i have now found all the explanations thanks to a couple of VFX experts that helped me yesterday, its all good
the gamma shift is due to having a wide gamut monitor and color management off, once color management is on we are seeing the right response as the output adapts to an specific color space
have a great day
jav


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 6:53:38 pm

the final doubt i have is this,
i want to work in linear space, 32 bits, and all my grading is done with the Colorista ii plugin in AE, it seems to be working but i read today this

"The advantages and techniques of working linear are well-covered on my blog and in Mark's book. Linear isn't better for everything, and Colorista is an example of an effect that works better in gamma-encoded space (or log) than in linear. "

so i need to find out if Colorista ii is not really ready for linear space, or if the new version, the ii, is ok for linear space,

any ideas?
best
jav


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Walter Soyka
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 7:26:27 pm

[javier gonzalez] "so i need to find out if Colorista ii is not really ready for linear space, or if the new version, the ii, is ok for linear space"

It's not Colorista II itself that's not well-suited for linear work -- it's that color correction techinques generally behave differently in linear space than they do in a display-corrected space. Any gamma adjustments you make during color correction in linear may have unintended consequences.

See Stu Maschwitz's blog post Color correction in linear vs. gamma corrected space [link] for more.

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
Creative Cow Forum Host: Live & Stage Events


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 7:34:20 pm

i understand and yes i have read many articles and i was worried about that as well; when you mean any gamma change, you mean changes in the luminosity of midtones, shadows or highlights (gain, etc) as opposed to pure changes of color in the color wheels?

im trying to understand if gamma changes refer to actually any changes of brightness in the colorista color wheels

i have been testing and certainly i see how it behaves differently, its very clear to me, although it also seems totally usable, it just behaves differently, but as you say, i have read in other places also about the problems that can happen when changing gamma, so i need to understand what exactly you are referring to when you say changes in gamma, (as we all know gamma is a word we use for describing 1000 things :) ),

are we referring to changes of luminosity in the outside of the color wheels (in shadows, midtones or highlights)

or are we referring to changing the gamma with the Curve controls instead?

or are we referring to what exactly

are we saying that its only safe to change the chroma channels but that anything that changes luminosity can have risks to degrade the image?

are we saying that in general is just a more delicate process that can potentially degrade the quality of the final result?

please give me some light on this :)
thank you :)


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 7:56:20 pm

so if a few people are advising not to use linear with colorista ii, then i may have to change, and at the same time if i take linear out, the Universal Print working space i wanted to use seems to behave weirdly in non-linear way,
so i may have to go back to REC709 in non linear as long as use Colorista ii for the grading, oh well, thats a pity

in future i plan to move to using Resolve from davinci and i guess that will be linear all the way

im still trying to find out though for sure that the latest version colorista ii is ok or not to work with linear, or to understand what those changes in gamma people talk about mean

thanks :)


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 8:50:48 pm

i read this article
http://prolost.com/blog/2005/1/26/color-correction-in-linear-vs-gamma-corre...

and now i start to understand some of the weird things i have seen while using colorista ii in some tests yesterday in linear,

i could see that in the highlights strange tintings were happening, obviously after some gamma changes, so now i start to understand some of the risks...

its obvious that to use linear in grading one has to be careful and know what one is doing, at the same time doing any gamma changes at the end, i dont know, sounds complicated, im used to be doing all gamma changes either at beginning or combined with the rest through the process,

all in all it may be safer to stay in non linear with colorista ii in AE, and then i guess stay in a REC709 working space (instead of the intended Universal print density space as that one doesnt seem to work correctly in non linear)


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 8:53:48 pm

maybe color grading in linear spaces (and universal print density) only makes sense with a da vinci resolve, lustre, color or similars?


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Walter Soyka
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 9:00:05 pm

By gamma, I meant the power function that bends a luminance curve away from linearity. This can be adjusted several ways, including the wheels or the curves controls.

If you look at the example that I referred to on Stu's blog, you'll see that when he warms up image with gamma adjustments in the RGB channels, the result bends the gamma curve the other way in the superbrights, actually cooling superbrights (as illustrated by the inset circle in image 4). This is not immediately obvious, because the new color cast exists in the superbrights only, but it would affect subsequent linear compositing or additional adjustments. There are more obvious effects in the shadows specifically, and the contrast in general.

Then, he illustrates how multiplying the image in linear space with constant RGB values removes the cast without adversely affecting contrast and superbrights.

Personally, I wouldn't color grade in linear, because the tools I am accustomed to using won't work the way I'm accustomed to using them. I'd composite in linear, then grade in non-linear. If you wanted to keep composited elements separate for grading, maybe export mattes during compositing and use them for your grades.

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
Creative Cow Forum Host: Live & Stage Events


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javier gonzalez
Re: AE cs5.5 color management 5D Mark II issue
on Nov 14, 2011 at 9:07:43 pm

This makes all the sense, thank you very much and it also matches with others saying that linear space is good for compositing and VFX but not that needed for color grading

great, so i will go back to Non-Linear in REC709 working space and 32 bits in AE

i wanted to use universal print density working space in case i go to cinema in future, but it doesnt seem to work well in non-linear mode so i guess i will go to REC709 as i read there are some LUTs that potentially allow to go from REC709 to the Cinema Log spaces in case thats needed in future, any opinion about this? (setting working space REC709 as opposed to non-linear universal density print in AE if thats possible, im using Canon 5D Mark II native non transcoded footage)

thank you very much :)


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