Post Production

After Effects and Alexa – Part 1

Working with Arri Log C footage in After Effects

The Arri Alexa is a hugely popular digital camera, but it records footage in a proprietary Arri colourspace called Log C.  While there are many ways of working with Log C footage in After Effects, none of them are immediately obvious – and if you’re new to log colourspaces then it can be a bit of a shock to import a footage file and see it looking flat and washed out.

The bigger issue is if you have to deliver a Log C file out of After Effects, because again there is no obvious way to do a round trip.  While this may not be a common situation, if it’s something you’re asked to do it’s something you need to do correctly.

Looking at the best way of working with Log C footage opens up a whole can of worms to do with colourspace and colour management, and so this video presentation has expanded out into two comprehensive parts.

In part 1, I introduce the problems that different colourspaces pose.  Colour can be such a confusing subject that it’s important to define exactly what we’re talking about.  This gives us a solid base to understand what Log C footage is, why it’s useful, and what we need to do to work with it.  This isn’t exactly simple, so part 1 is an overview of colourspaces, colour management, 32bit float images, and logarithmic file formats.  It’s all of the background information you should have to work with colour professionally.

In part 2, I specifically look at the Arri Log C colourspace, and compare different methods of working with it in After Effects.  While I have my preferred workflow, it’s worth noting some other approaches.  And at the very end, I do a quick demonstration to show that the actual process only takes a few seconds.

However I also understand that not everyone wants to sit through 40 minutes of video and listen to someone waffle on about colourspaces just to be shown a few mouse clicks.  So I’ve also put together a very short cutdown that demonstrates what I think is the best technique.  The expurgated version cuts out all of the explanation and comparisons and demonstrates the most elegant workflow in about 3 minutes.



Although it mightn’t seem like it, these videos are a very quick introduction to some very serious topics.  The diagrams used in part 1 are quite simple and are not intended to be to scale – the intention is only to introduce the subject.

There are many resources out there on colour management, and if you’re after some that are more precise and in-depth, then start here:

Adobe article on colour management in After Effects.

Arri website page on Log C and rec709 colourspaces.

Information on the Kodak Cineon format.


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Chris was born a geek, and was lucky enough to own a Commodore 64 at a time when the number of students at his primary school who owned a computer could be counted on one…