does alpha transparency work ?

jbeale1 wrote on 3/30/2003, 4:25 PM
A title sequence I'm doing requires a transparency effect which I ought to be able to do with an alpha channel. I'm using Vegas 4 and Photoshop 7. I have created my alpha channel in Photoshop and saved the image as a one-layer PSD file with four channels (R,G,B,A). I can load it back in Photoshop and all channels appear as expected, including the alpha channel as a red area when I enable that in the channel dialogue.

Now I can import the PSD into the top video track in V4, but it behaves as though there were no alpha channel (ie, whole image is entirely opaque; lower video tracks don't show through).
I have set the top track's compositing mode to "Source Alpha" and the Event Properties/Media/Alpha channel to "Straight (unmatted)" and also "premultiplied" but nothing works, it's still all opaque. Is there some other setting I've missed? Has anyone got source image alpha transparency to work in V4 ?

Comments

BillyBoy wrote on 3/30/2003, 6:40 PM
You don't really need a parent child track relationship for simple transparencies. Just drop the Photoshop file on a track ABOVE your main track. I wrote a short tutorial (number 5) that shows basically what you want and the video that goes with the tutorial is somewhere on Chinework's site. I think I called it bird mask or something like that.

http://www.wideopenwest.com/%7Ewvg/tutorial-menu.htm


Found it:

http://www.vegasusers.com/vidshare/textdisp?billyboy-bird-mask-3d.txt
Grazie wrote on 3/31/2003, 12:15 AM
BB is correct - I too got myself in a mess until I placed the "graphic" on its own track ABOVE the clip I wanted to "show" through the "graphic".

Grazie
jbeale1 wrote on 3/31/2003, 1:49 AM
Thanks for the help, and for this link which shows exactly what I'm trying to do: http://www.wideopenwest.com/%7Ewvg/tutorial-5.htm

Problem is, it doesn't work that way for me. In the above link it shows the bird still frame on the timeline above the background, with the masked out portion transparent (with the greytone checkerboard background). OK, I saved my R-G-B-A image from photoshop as a PSD and imported into Vegas 4, and put it on the timeline, but it does NOT show any regions transparent, as the above example does. Is there more than one kind of alpha channel, could I be saving the PSD wrong? But when I re-load the PSD into Photoshop, the alpha channel is there. Is Vegas 4 not compatible with Photoshop 7? I can't figure it out.

Tyler.Durden wrote on 3/31/2003, 5:19 AM
Hi John,

You may need to tell Vegas to turn on the alpha by rightclicking the media or event and selecting premultiplied from the alpha menu.





HTH, MPH

Tips:
http://www.martyhedler.com/homepage/Vegas_Tutorials.html

BillyBoy wrote on 3/31/2003, 7:45 AM
I didn't save the veg file, so trying to remember if I did anything special. I don't think so.

However I seem to remember if you try to drop a transparancy on the timeline where you already have a parent/child relationship it may not work as expected. Try using two new tracks where you don't have any parent/child compositing setup.