FCP to AE and back again: lightness change…

[Chris Smith]

You are having the standard problem of converting from YUV to RGB to YUV.

FCP defaults to working in YUV space when working with a YUV codec like DV.
AE is 100% RGB internally. So a conversion must be made. Unfortunately, YUV and RGB use color space a little bit differently. RGB considers black to white to be 0 to 255. YUV considers it to be 16 to 235. Above and below 16 and 235 are “Super White” and “Super Black” and are buffer zones.

So say you have some thing in FCP that is black. It sits at 16 in YUV color space. FCP makes it look black. Bring that into AE. Now it’s not really black, it’s slightly lighter than black because AE sees black as 0. Then when you save back out to DV. AE compresses the RGB spectrum to fit into the YUV space making your light black even lighter. By time you get this back into FCP, your contrast has dropped a bit.

There are a few things you could do. You could use levels to fix the luminance in AE to RGB. So you would add a levels to your overall footage. Make sure levels is showing value and not percent. Put the black at 16 and the whites at 235. Which will expand the color space to fit RGB.

Or you can save to an RGB codec like Animation and set FCP timeline settings to Always use RGB instead of YUV.

But I may add that using DV as a intermediate codec is a very bad idea. It just recompresses repeatedly. So use a lossy codec to trnsfer to and from AE like Animation at best settings. Plus if you want to keep an alpha channel, Animation codec supports one when using millions of colors+. DV does not support an Alpha channel.

Chris Smith
https://www.sugarfilmproduction.com

[Trevor Gilchrist]

Wow.
Thank you so much for your comprehensive and speedy reply. Now I get it.

Very much appreciated.

Trevor