Alpha Problem in FCP X that docent happen in FCP 7

Apple Final Cut Pro

Alpha Problem in FCP X that docent happen in FCP 7

Posted by Ricky Dominguez on February 21, 2013 at 5:14 pm

I have a graphic that was created in After Effects with alpha premultiplied and exported as a ProRes 4444. I import the graphic in FCP X and I add a black generator and as a connected clip I add the After Effects with alpha premultiplied graphic and it’s not doing a good job, as you can see in the still that I include (FCP X.jpg) the colors are different, the quality it is like low resolution and it have a hallo. If I change the alpha handling to None/Ignore Alpha it is like it’s suppose to be and with good quality so I suppose that the problem is with the Alpha.

I also did the same test in FCP 7 a black generator track 1 and in track 2 I add the After Effects graphic with alpha premultiplied graphic and I don’t have the problem with the Alpha. I also include a still (FCP 7.jpg).

So any help would be appreciated way in FCP 7 is OK and in FCP X don’t work.

Thanks,
Ricky Dominguez
Luna Films
Puerto Rico

T. Payton replied 13 years, 2 months ago 3 Members · 12 Replies
12 Replies

Ricky Dominguez
February 21, 2013 at 6:15 pm

Sorry the stills

FCPX
https://dl.dropbox.com/u/847397/FCP%20X.jpg

FCP 7
https://dl.dropbox.com/u/847397/FCP%207.jpg
T. Payton
February 22, 2013 at 12:02 am

I heard about something like this but I can’t quite remember the fix. Any chance you could post a still of that graphic with the alpha. Perhaps just a few frames of the ProRes 4444?

——
T. Payton
OneCreative, Albuquerque
Bret Williams
February 22, 2013 at 7:10 am

Sounds like its interpreting as straight (which is always a higher quality alpha, you should use that whenever possible). Highlight the clip and go to the inspector and make sure it’s interpreting it as premiltiplied. I can’t tell anything from your stills.
Ricky Dominguez
February 22, 2013 at 6:52 pm

Thanks Payton and Bret for the replay.

Payton her I have a link with a ProRes 4444 and it is 1 second and the file is 30mb.

https://www.dropbox.com/s/nptp9xa43feoddg/ProRes%204444%20Premultiplied.mov

Bret and Payton the files is ProRes 4444 premultiplied, FCP X interpret the alpha as straight so I change to premultiplied in inspector.

The graphic artist export the video in different codec:
ProRes 4444, uncompressed and none in version straight and version premultiplied, and all of them give the same alpha problem in FCP X.

Seen this problem the artist give me the animation without the alpha, the alpha was given as matte so I can combine in FCP X with compositing blend mode stencil alpha, this one work perfect.

I try the animation in all the version in FCP 7 and I didn’t have the alpha problem .

The final test that I did today is I toke the ProRes 4444 and add the Boris BBC Alpha Process and I lower the Gamma value from 1 to .50 and it work. So I think that FCP X change the alpha gamma.

Again thanks Bret and Payton for the help and have a good weekend.

Ricky Dominguez
Luna Films
Puerto Rico
Bret Williams
February 22, 2013 at 9:36 pm

I’ve been working on exporting 4444 FCP X keyed individuals to AE, (FCPX exports as premultiplied btw) , then bringing them back from AE as 4444 straight alpha wiht other elements added (X often interprets as premultiplied and I fix) and no issues. All works just like it did in 7 for me.
T. Payton
February 22, 2013 at 11:29 pm

I created a green PSD file then just grabbed your footage and dragged in into FCP X, AE CS6 and FCP 7. FCP X identified the file as premultiplied so I didn’t do anything. AE required me to change the interpretation to premultiply. FCP 7 I changed the Alpha Settings to “black”.

So here are the results (gamma adjusted so the outputs match)

I’m not seeing anything like you described. And it appears that FCP X is the most correct. Correctly interpreting and compositing the Alpha, with an image that matches AE. FCP 7 is darker and looks incorrect. Check out the yellow and green dots especially.

It was odd that your FCP X was interpenetrating the Alpha as straight. Are you on 10.0.7?

Also is this any help?

——
T. Payton
OneCreative, Albuquerque
Bret Williams
February 23, 2013 at 5:26 am

You’re looking at green dots, but what I see is the bad dark fringe in the FCP 7 alpha key. But that’s to be expected in a premultiply in FCP 7. Probably one reason I always use straight. I see the darker dots, but I would attribute that to any gamma shifts/corrections you had to do, no?
Ricky Dominguez
February 25, 2013 at 6:46 pm

Again thanks for the time to help, I really don’t know what it’s happening I my FCPX that it’s 10.0.7 Payton.

I did what you did create a green back as you did and I don’t have the problem, but if I take that green background and I make it darker it show what I have been talking, low quality and the hallo around the color particle.
I include two stills one created as Payton do the test with a green background and one with the darker green background.

stillwithpaytongreenbutdarker.jpg
stillwithpaytongreen.jpg

Thanks Again, Ricky
Ricky Dominguez
February 25, 2013 at 6:48 pm

Sorry the stills are here:

https://dl.dropbox.com/u/847397/Still%20with%20Payton%20Green.jpg

https://dl.dropbox.com/u/847397/Still%20with%20Payton%20Green%20but%20darker.jpg
T. Payton
February 25, 2013 at 7:55 pm

I think I have a fix for you. In “Info” Settings View, Change the Alpha Handling to Straight and then in the timeline itself set the Compositing Blend Mode to “Premultiplied Mix”.

This might not be prefect, but at least there are no halos or artifacts. How does it look to you?

——
T. Payton
OneCreative, Albuquerque

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