Problem with fade to black of layered clips with white backgrounds

[Petter Stahre]

I would just like to confirm that I guess I’ve run into the same problem, but I’m sorry to say I have yet to find a good solution.

A situation similar to what you describe can be repeated in FCPX by doing this:
– Create a clip containing a solid background (generator) 100% white (RGB 255,255,255).
– Make a copy of the clip, crop it or trim it and color it light grey (I used 90% white).
– You should now have a white background with a light grey rectangle somewhere.
– Mark them and make a compound clip (CC).
– Color correct the CC by changing the exposure so that the light grey rectangle disappears – all should seem to be white.
– Now good luck in trying to make a good transition using that CC 🙂

What I guess is happening is that the color values that FCPX is using internally for calculations can be over 255 (and under 0 I guess). Like a raw-image in Photoshop until you convert it.

So the two whites in the CC in my case becomes something like RGB 255,255,255 and RGB 280,280,280 which all displays as solid whites until you start to do calculations with them, then their actual color value is used – thus the difference during transitions.

Anyone awake? 😉

This is what the CC looks like in FCPX:

This is the CC when I apply an exposure correction (+11% overall):

And this is how the transition looks when I move the playhead:

Even if you create the transition using a separate clip above/under the CC the same happens.

It would be super if FCPX had some kind of limiter / clipping functionality that said all values under or over RGB 0 / 255 for this clip should be calculated as no less than 0 or no more than 255.

At least this is what I guess the problem is about but I would be very glad if I’m wrong and if there is a simple solution to this.

Best,
Petter

[Jeremy Garchow]

A luma key fixes it.

Here’s David’s video with a luma key, new white BG, and slug fade:

https://reels.creativecow.net/film/luma

[Nick Toth]

Do the luma key. I’ve been doing it since the days of video switchers and tube cameras. The same idea carries forward into today’s NLE’s. Why make it difficult?

Also, you can’t apply overall color correction to your white clips. You have to correct one white clip to match the other.

anickt

[Petter Stahre]

Couldn’t see the video (it starts/stops within 1 sec) but I think I get what you mean.

Thanks for the information, will try that next time!

[Jeremy Garchow]

[Petter Stahre] “Couldn’t see the video (it starts/stops within 1 sec) but I think I get what you mean.”

I took the beginning of your movie, so it’s short!

Here’s a file of it: 7463_untitledproject.mp4.zip

[Petter Stahre]

[Nick Toth] “Do the luma key. I’ve been doing it since the days of video switchers and tube cameras. The same idea carries forward into today’s NLE’s. Why make it difficult?

And why stop making it easier? 😉
I understand the luma mask concept but think it could be much easier and less time consuming. A simple checkbox for the clip could do the job (“Clip values outside 0-255”).

[Nick Toth] Also, you can’t apply overall color correction to your white clips. You have to correct one white clip to match the other.”

I made the situation up only to show that what seems matched on screen could still have different color values.

In my own case I noticed the problem when I was working with a movie clip and tried to get the over exposed whites become 5% grey. A luma mask would probably have been the solution.

Thanks for your input.

[Petter Stahre]

[Jeremy Garchow] “I took the beginning of your movie, so it’s short!
“

Ah… not my video, but thank’s for the effort.

[Jeremy Garchow]

Oops, David’s video.

Apologies.

[David Meister]

Thank you all for your help. Luma key and fade with a slug on top works for me.

I agree with Petter, FCP X must have white levels beyond 255. Is there any point in having that? I know that you can go beyond 255 if you work in HDR 32 bits. Can FCP X do that? I know that in AE you can do some fun stuff by animating HDR material… Anyway, that’s off thread. Thanks again. David