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Straight alpha matte out of After Effects into Final Cut Pro 7 luminance shift
Hello,
I’ve scoured the Internet but can’t find an answer to this. Maybe somebody can point me in the right direction.
I have been creating lower thirds in After Effects CS6 and exporting using Animation Codec with RGB+, straight alpha. I’m using QuickTime 7.6.6 as well.
When I import the lower third into Final Cut Pro 7.03, I place the lower third over my video and all looks and works fine. However, I notice there is a slight luminance shift (gets slightly brighter) when the lower third comes on and off. In addition to the luminance shift, the picture also gets slightly softer as if it the alpha was acting as a filter.
I’m guessing it has to do with AE being RGB based and FCP being YUV…but I can’t figure out how to eliminate this luminance shift. It’s driving me nuts. I’m guessing it’s something really simple.
Thanks for any help you may offer.
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10 Replies
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Hi David
I have had this happen a couple of times where the luminance changes with the addition of the super. Both times it turned out that the matte (alpha) was not quite 100% white but something very slightly off like 99.97% – making that 100% fixed the issue.
I hope it is something that easy.
best wishes
Neil
http://www.patience.tv8 Core MacPro, Kona 3, Tangent Wave, Mackie Universal Symphony 6.5 FCP7
i7 2.7 Gig MBP (non retina) 16Gigs Ram Blackmagic Monitor Mini Symphony 6.5 FCP7 -
Thank you for your answer. That makes sense. Where did you get your reading of 99.7% for the alpha? Also, how did you tweak the alpha? Or is just a matter of adding levels within FCP and adjusting the white level manually?
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Hi David
To be honest the 99.7% for the alpha was a made up number, I can’t remember now exactly what it was but it turned out the alpha channel was causing the key to be slightly “transparent” and was not totally keying out. I am not an AE guy but coincidentally the week before I had some still images with a separate matte sent to me and that matte was not quite 100% white so it pretty much had the same effect. So I figured the alpha was possibly the issue, just called up the guy that did the AE and he realised straight away the problem was able to pretty quickly adjust and all was good.
best wishes
Neil
http://www.patience.tv8 Core MacPro, Kona 3, Tangent Wave, Mackie Universal Symphony 6.5 FCP7
i7 2.7 Gig MBP (non retina) 16Gigs Ram Blackmagic Monitor Mini Symphony 6.5 FCP7 -
Ah, I understand. Well, this gives me something to look into so thanks again.
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Try change alpha interpretation inside fcp under alpha try premultipled with black or white.
Massimo Alberto Croce
Video Editor, Colorist, Pro Tools Editor
massimoalberto.croce@gmail.com -
Thanks, I’ll give that a try too.
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[Massimo Alberto Croce] “Try change alpha interpretation inside fcp under alpha try premultipled with black or white.”
FCP prefers Straight alpha; is his natural alpha option.
rafael -
[Rafael Amador] “FCP prefers Straight alpha; is his natural alpha option”
Yes, I Know.
But sometimes change interpretation solve my issue with alpha channel.Massimo Alberto Croce
Video Editor, Colorist, Pro Tools Editor
massimoalberto.croce@gmail.com -
Thanks for all the suggestions. I’m away from the office but when I get back in, I’m going to try the Pro Res 4444 and the QT PNG codec.
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