After Effects -> Compressor Changes Colour

Hi all,

I'm currently working on a video that involves adding an effect in After Effects, then editing in FCPX. The files are huge when I export from AE so I need to run them through something like Compressor. I don't have Adobe Media Encoder. I'm getting a colour change when I do this; the files run through Compressor are a bit brighter, I think they've lost some contrast. They all look pretty much identical, no matter what codec I use (I've tried 6 or 7).

Weirdly, I've found a more convoluted process that does work: export from AE -> open with QuickTime (which "converts" the file -- I'm not sure what it's doing exactly but it cuts the file size in ~1/3) -> import to FCPX -> export FROM FCPX as H.264 -> now it's a manageable size and still looks fine, no weird colour change.

There's probably something I'm not understanding in here but in general Compressor hasn't given me problems in the past so I'm a little confused by this. Any suggestions?