Alpha in final cut pro

cribble · Post by **cribble** » Tue Jan 23, 2007 9:59 pm

So i got a copy of Final Cut Pro from my college. Yay.

So i was experimenting implementing animation on top of video, but ran into a problem. When i import my quicktime file (alpha enabled), i loose the colour of the image. It also turns very dark on light colours and dark colours turn really bright, and a bit transparent (when it's meant to be a solid colour).

Anyone know how to correct it back to its original colour and solid...ness?

love

heyvern · Post by **heyvern** » Tue Jan 23, 2007 11:34 pm

Uh... hate to say this but the alpha channels from AS don't work that great.

For some reason the alpha transparency channel from AS uses the "values" of the colors for the alpha channel... or something odd like that.

I am only guessing but this might be why you are getting strange things in compositing.

I have never been able to use alpha channels from AS. The only way I could get proper transparency was rendering a file sequence out to PSD witch puts each layer from AS to layers in PS.

-vern

slowtiger · Post by **slowtiger** » Wed Jan 24, 2007 12:07 am

That can't be the full answer.

I just did a test with two small scenes from AS which I rendered and imported into Mirage. One was completely OK, the other showed the odd transparency you mentioned. The first result is that correct transparency (alpha) is possible to achieve. Now I had a closer look at the two scenes to spot the difference in coloring - it had to be the coloring.

Second result: the scene in which I colored my character completely with styles was the one with correct alpha! The other one had no styles at all.

Would others please test their scenes and post the results here. Codec: Animation, with Millions+ colours. Watch for shapes with styles applied in opposite to shapes without styles.

cribble · Post by **cribble** » Wed Jan 24, 2007 2:21 pm

So it's not just me having the problem. Odd... surely this should be something that... well... AS should have initially. Or is it a codec fault. I'm using:

Animation
Million Colours+

Do i need to pre-multiply alpha (or what ever that option is)?

F.M. · Post by **F.M.** » Wed Jan 24, 2007 5:37 pm

I always use Quicktime to save movie files when I need the Alpha channel to work properly. Settings: Animation Millions of colors+ (Quality) Best.

heyvern · Post by **heyvern** » Thu Jan 25, 2007 1:50 am

I do a lot of print illustration work now using AS and have found that exporting one frame as a psd sequence was the best way to get perfect transparency, it actually gives me the layers.

I've never used it but does FCP import layered Photoshop documents? That might be a cool way to get a whole complex AS file into it with each element on layers.

I did an illustration with like... 7 characters in their own folders in AS. Ended up with a layered photoshop document with each character in it's own layer for easy moving and adjusting.

-vern

cribble · Post by **cribble** » Thu Jan 25, 2007 2:21 am

Sounds like a painful plan. I have jotted it down and will give it a shot... sometime.... soon.

slowtiger · Post by **slowtiger** » Sun Jan 28, 2007 11:45 pm

This alpha channel testing drives me crazy. (But thanks to cribble to point to that bug (it must be one) because discovering it later in real work would have been a catastrophy!)

I have a moho file. I had built the character with normal fills etc, no styles. I rendered it with alpha, and on import it turned out that the character was transparent.

Then I created some styles and applied them (different colours, just to be sure to really change it). Rendered the file, but: no change! The character still is semi-transparent.

I tried a lot: erase every fill before applying the style, checking every level's properties ... The only thing that works seems to be to choose a style first and then draw a completely new shape with it. This is the only thing wich turns out opaque in the rendered QT.

A file in which I had created the styles before I drew any shape is OK, I can easily create new styles and apply them where another style was, and it renders OK.

Any ideas?

heyvern · Post by **heyvern** » Mon Jan 29, 2007 12:03 am

When you create a shape it has a fill style already. When you apply a style to an existing shape the "old" fill style is sort of there already... waiting in limbo.

I wonder if this might have something to do with it?

There are a bunch of check boxes for styles in both places, the fill shape's default style and the "external" style. Are any of these... inconsistently checked or unchecked? You can check things and they sort of stay checked but are grayed out. I've often wondered what is happening in those situations.

Sorry for you troubles but I am glad that this "puzzle" has an explanation. Please post this info in the bugs section. It is important.

-vern

cribble · Post by **cribble** » Wed Jan 31, 2007 5:02 pm

See, here's something else to throw into the works. Does this happen with any video exported from different software, or just the ones exported from AS(S hehehe)?

slowtiger · Post by **slowtiger** » Wed Jan 31, 2007 11:46 pm

Uhm, the bug works on export, means: within Moho/AS.

Import with alpha should be fine in any program. If you have problems to get _any_ alpha, check the importing program's settings. If some file fromm one program are fine and others from another program are not, check that program's export settings.

DarthFurby · Post by **DarthFurby** » Tue Feb 06, 2007 1:04 am

It almost sounds like you have a layer blending mode turned on. I've never used Final Cut but check the settings for the background and alpha layer blending modes. The default should be "Normal", but you never know. Make sure there aren't any matte settings turned on either.

Also when you import video with alpha sometimes you have to tell the program that you are importing either straight unmatted alpha, or premultiplied alpha. When opened in Quicktime, straight unmatted alpha can be frightening to look at(unlike premultiplied), but should import properly in a good compositor. (I prefer to export straight unmatted. Premultiplied picks up some of the background color for things like clouds and smoke.)

slowtiger · Post by **slowtiger** » Tue Feb 06, 2007 10:12 am

This doesn't meet the point. I've tested the AS video output in other programs than Final Cut, and the result is still the same: half-transparent characters (not wanted) on a transparent background (that's OK). The bug is clearly within the file rendered from AS.

cribble · Post by **cribble** » Tue Feb 06, 2007 7:19 pm

gaaayyyyy

DarthFurby · Post by **DarthFurby** » Wed Feb 07, 2007 1:32 am

I exported both premultiplied and straight unmatted alpha clips from AS and it imports perfectly in both Flash and After Effects.

I'm on a PC so maybe this is a bug specific to the Mac version, but I'd still double check your layer settings in Final Cut Pro.