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Gamma shift on export, but not visible within After Effects

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Stuart ElithGamma shift on export, but not visible within After Effects
by on Aug 19, 2011 at 5:45:59 am

Hi all,

We're getting a strange problem with gamma/color shift in files rendered from After Effects. We were supplied FCP Uncompressed 10-Bit 4:2:2 footage, which I have VFX'ed and rendered out. Here's what we are experiencing :

- The post facility say that the gamma is shifting.
- If I open the files in Quicktime or FCP, I can see the difference they are referring to.
- When I re-import the render into AE, it looks identical to the original footage.
- I have tried a number of renders from AE, including re-rendering JUST the original footage in the FCP codec, Animation, as well as 16-bit. All look the same when I bring them back into AE.

- When we pull the original footage and one of my renders (that appears the same in AE) into FCP, we can see the difference, and when I render the two clips out of FCP and bring that render back into AE, suddenly we CAN see the difference.

So it seems that AE is doing some kind of compensation or treatment of the files, but I have no idea what. As far as I can remember, we haven't changed any settings or installed a new QT recently, and we haven't had reports of this problem in the past (but I suppose they *could* have existed for a while and we just hadn't noticed).

Any thoughts?
- Stuart


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Tudor "Ted" JelescuRe: Gamma shift on export, but not visible within After Effects
by on Aug 19, 2011 at 11:13:20 am

What version of AE are you using?
Are you using color management?
Did you try rendering out a few uncompressed stills (tga, Tiff or PNG) to see if the color shift is the same?

Tudor "Ted" Jelescu
Senior VFX Artist


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Stuart ElithRe: Gamma shift on export, but not visible within After Effects
by on Aug 22, 2011 at 2:06:26 am

Thanks for the quick reply, Tudor.

I'm using AE CS5 (should have mentioned that earlier!) on a Mac running Leopard.

Color management is off, which is how we've always done things.

I have just tried rendering out some stills:

When I render a dpx or PNG , I still get gamma shift if I import back into FCP, and I still don't see the gamma shift in AE.

Interestingly, I have checked some footage we received in dpx sequence from another post facility, and when I render out an image from that sequence, there is no gamma shift (checked in photoshop as FCP doesn't seem to accept dpx). So it does seem to be something QT related.


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Stefan HinzeRe: Gamma shift on export, but not visible within After Effects
by on Aug 19, 2011 at 11:15:50 am

There is a lot of info to this Toppic - Try the Forum and some Serchengine...

I hope i am allowed to post some links:

http://blogs.adobe.com/toddkopriva/2009/12/prores-4444-colors-and-gamma-s.h...

http://kb2.adobe.com/cps/402/kb402801.html

VCP Solution:

http://www.videocopilot.net/blog/2008/06/fix-quicktime-gamma-shift/

hope this helps!
Steven

(take a step back, to see the bigger picture)


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Stefan HinzeRe: Gamma shift on export, but not visible within After Effects
by on Aug 19, 2011 at 11:18:20 am

Ted is right, try the Image-Sequenz!
Worked for me!

Greetings

(take a step back, to see the bigger picture)


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