Background colour is showing in ProRes 4444 exports for transparent layers

[zh55667]

I have a project with a lower third and a book mockup with some keyframed opacity and some shadows, which I've used multiple times. I've never had any issues with this setup until I recently changed the comp background colour to make it easier to see what I was working on.

I'm under the impression that this background colour should not be visible in the final render, but any part of the lower third that has partial opacity (not 0 or 100%) will be changed to the background colour, still with opacity applied. So a grey/black shadow or fade will appear green if the background colour is set to green, and as an asset fades up, it will go from darker to brighter.

This colour change is not visible in the composition window but is visible in Quicktime and when imported into Premiere Pro or After Effects.

I've tried exporting from both After Effects 22.6.5 and 24.1.0

The Render settings I have tried are:

Field render: Off/Upper Field

All other settings are default for "Best settings"

The Output Module settings I have tried:

Quicktime Apple ProRes 4444

RGB + Alpha

Color: Premultiplied/Straight

I have also tried exporting as PNG, TIFF and Quicktime Uncompressed RGB 8-bit it does not show the background colour, as expected. Is this an issue with the ProRes 4444 codec or something else?

Also note in the second screenshot, the red border is visible in quicktime but not in PP or AE.

I hope this is enough info for you.

Thanks!

[zh55667]

I wasn't sure if I could edit but I thought I'd add:

OS is MacOS Ventura 13.6.3

[nishu_kush]

Sorry for the delayed response. Are you still having the issue?
Feel free to reach out.
I am moving this thread from Bugs to Discussions for now.

Thanks,
Nishu

[zh55667]

Hey! No worries. Yes I am still having the issue, though testing again I notice that exporting as Straight (Unmatted) fixes the issue.

I'm not sure what I did different before but I thought setting Color to Straight still showed the Background colour but that must have been incorrect.

I am still seeing the Background colour on Quicktime ProRes 4444 and 4444XQ when exporting with Premultiplied (Matted) selected.

An interesting thing I noticed is when you import this footage into Premiere Pro the border of the Background colour is very harsh in the preview window, with no gradient on the transparency, but when I choose Export Frame the transparency is smooth (might just be how premultiplied works but I found it intriguing). When you interpret the footage to "Ignore Alpha Channel" the entire preview window goes green (whatever colour was selected as the Background colour in AE).

I've added a bunch of screenshots of my AE exports as well as frame exports from Premiere Pro of how they appear there.

I'm seeing the same results from AE versions 22.6.5, 23.6.5, and 24.3.0. Now on Mac OS Ventura 13.6.6.

Thanks so much for any help

[nishu_kush]

Thanks for sharing the details. I wasn't able to reproduce the issue on my end with the settings you provided. I can see the background color in Quick Time but not in Premiere Pro or After Effects. Could you share a project file with us that repeats the problem at your end?

Feel free to DM me.

Thanks,

Nishu

[zh55667]

Sorry for the long wait. Here is a new project file I've made with some shape layers and text. Export as Quicktime 4444 RGB + Alpha and you can see the assets with opacity, like gradient, will appear blue.

I've attached a video as well which was exported with these settings, then compressed as h264 to upload here.

Thanks!