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Brightness/Color shift

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craig whitBrightness/Color shift
by on Feb 21, 2010 at 1:24:02 am


I have a piece of 1080 footage that has the following codec "Uncompressed Component Y'CbCr 10-bit 4:22" This is the first time I've worked with footage this heavy so I made a 264 version to work with in my comp. When I view both clips in QT, they look very similar. When I go to replace the hi-res version in my comp with the newer, low res clip, there is a drastic brightness/color shift. The 264 clip is much darker as you can see. As I said, I'm new to this quality/codec so any help is greatly appreciated. The deliverables are due on Friday and I'm feeling the pinch. Thanks everyone.


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Walter SoykaRe: Brightness/Color shift
by on Feb 21, 2010 at 1:34:16 am

Here's an Adobe document on gamma shifts; it may give you some useful information.

That aside, I'd recommend against using h264 footage in After Effects. I hope Dave LaRonde doesn't mind if I parrot his stock answer on the topic:

Dave's Stock Answer #1:
If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, mp4, m2t, H.261 or H.264 -- you need to convert it to a different codec.

These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.

In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.

You'd be better off using a codec like DVCPRO HD or ProRes.

Walter Soyka
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Todd KoprivaRe: Brightness/Color shift
by on Feb 21, 2010 at 1:49:43 am

First, I need to make sure that you're rendering and exporting through the render queue. If you're using QuickTime components to export through the File > Export menu, I can't help you; you're doomed.

If you are rendering and exporting through the render queue, then I will urge you to use color management. That's the only way to really have control of your colors and ensure consistent color.

The document that Walter pointed to is about QuickTime-caused gamma shifts in non-color-managed projects. QuickTime has problems with gamma. We put in the Match Legacy After Effects QuickTime Gamma Adjustments option to give some control, but it's not always the solution.

There's a very informative thread here in which one of the After Effects engineering managers go on at quite some length about the QuickTime gamma issues. (The good parts are toward the end of the thread, in Chris Prosser's posts.)

Todd Kopriva, Adobe Systems Incorporated
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craig whitRe: Brightness/Color shift
by on Feb 21, 2010 at 2:27:51 am

Hey guys,

Thank you both for your fast replies.

I always use the render queue when exporting, however, I haven't got to that point yet with this project. So far, I received the uncompressed HD footage, made a 264 from it using QT 7 and am now a/b'ing them in AE. I will definitely try and make a ProRes version instead of 264 before I do anything else. Is it ok to use QT 7 for something like this or is that where I'm picking up the gamma problem? I'll have to read up on Color Management as well.


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Joey ForemanRe: Brightness/Color shift
by on Feb 21, 2010 at 4:42:45 am

Just to add to Todd's comprehensive response, I'd go with ProRes over DVCPro (if you're on a Mac), just because it, DVCPro, tends to default to its own flavor of non-square pixel aspect ratio, and can be a headache finding the correct one to implement for a round trip to your editing app.

ProRes retains your correct display dimensions, regardless of source codec or pixel aspect ratio.

It's more user-friendly.

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