Tuesday, October 30, 2007

Fun with Gamma, Quicktime and After Effects

Here’s a scenario being replayed at studios around the globe: The decision is made to upgrade to After Effects CS3. A big project comes in. All proceeds quite well until it’s time to render for final output, at which point files coming out of After Effects - particularly those being edited in Final Cut Pro - appear darker, even when rendered with a codec traditionally thought to be “safe” for gamma such as Photo-JPEG or even Animation (as was used to create this image). Howls of pain and gnashing of teeth ensue, After Effects is blamed, and in at least one case the entire studio reverts to 7.0. True story.

Don’t let this happen to you, folks.

Although there are various permutations of this problem, it generally comes back to rendering Quicktime movies directly from After Effects. “Why is After Effects messing with my Quicktime output?” you might ask. “Why doesn’t it just work like in previous versions?”

The short answer is that a simple checkbox may help you. Open Project Settings in After Effects CS3 and under Color Settings, toggle Match Legacy After Effects Quicktime Gamma Adjustments. This causes After Effects to work with QuickTime movies the same way as previous versions of After Effects. Boom. No need to set a Working Space or mess with gamma in any other way.

The longer answer is that gamma in Quicktime has essentially always been unpredictable for a couple of reasons: Apple changes the gamma according to their perception of how you’re viewing it (i.e. which platform you’re on, whether it’s a web codec, and what application is being used) and, being Apple, they haven’t published their gamma settings so that anyone else knows what the heck is going on, other than empirically.

Oh, don’t get me wrong Apple, I’m typing this on a MacBook Pro running Leopard, an iPhone at my left hand, Mac Pro behind it, ready to send this post via Airport Extreme.

I will likely have more to say on the subject of color management and I/O in After Effects, also a huge topic for the new edition of the book. Meanwhile, please freely post your horror stories (or revelations) here and I will scan them for more specific points to address. There’s also more to say about Quicktime and how it handles (or doesn’t) things like aspect ratio.

If you’re feeling bitter, boycott Quicktime until Apple and Adobe work this out together and use image sequences instead, like your pals who are film professionals.

By the way, here is a post from FreshDV a couple months back showing another culprit feature for unpredictable Quicktime gamma, in Quicktime 7.2’s very own preferences.

Compositing •
Software • (1) Comments • Most recent comments by: glennser, • Permalink

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