Creating Alpha Channel Mattes For Photoshop Images To Allow Overlaying In Cinestream

QUESTION:

What is the most elegant way to...

Take an image lets say from photoshop. Import it in to CineStream. And have it placed over a video track so the background video shows through where ever the imported image is not.
eg, adding a MasterCard logo over an existing video image, like in the top righthand corner.
In summary- How does one create an image for importing into CineStream, such that it has an alpha channel everywhere outside the image.

ANSWER:

Here goes:

1. In photoshop, create a document that is 640x480pixels @ 72 dpi (for NTSC, 720X576 for PAL) with a transparent background.
2. Import your image (i.e. visa card) into the document and place it where you want it to be in the video (note: if you don't already have a "safe title lineout" document that is photoshop importable you'll have to do a couple of tests to see where things disappear off the screen - the short: it is roughly 5/8" or a little more than a cm wide border around the document).
3. Once you've got it placed where you like, you'll need to accurately marquee it -- in older versions of photoshop, this can be done by hitting apple/option/T ( "select non-transparent pixels" ) in newer versions you can command click the layer in the layer palette ("select opaque pixels").
4. Now that your selection is properly marqueed, go to the SELECT menu and drag down to save selection. Your forthcoming dialogue box should default to "create new channel" (plus some other presently irrelevant things). Give your new channel a name and press return.
5. You've now created an aplha channel for your selection ( if you look in the "channels" window you'll see the normal RGB channels plus a fourth with the title you've assigned it. ) This document ( after it has been saved as a .pict file ) will key relatively well in most video applications.
6. To get a 'perfect' key you'll need to create another layer behind your present one and fill it entirely with black ( in apps like After Effects, you would then choose "matted with black" in the import file dialogue box ).
7. Now save the document, keeping it as a photoshop document in case you want to edit it later. You'll create the document that you actually import by doing "save a copy" and in the dialogue box choose File Type:PICT, preserve alpha, and flatten image and/or merge layers ( a lot of your selections will grey out as soon as you choose file type:pict, but be sure to select preserve/include alpha channel).
8. Now you can import your PICT into CineStream. Be sure to check "preserve alpha" when you do import ( it defaults to it anyway, but check to be sure) The import dialogue box will prompt you with a convert dialogue box.
9. The default aspect ratio on your imported pict ( the one on the left ) will be something like 720x480 -- you'll want to change the "720" to "640", your image on the right should then snap to fit its window. Hit return and it'll prompt you to save your new document as a .mov file. Hit return and now your document is in your bin and you can use it as video track 2 keying element over video that is in video track 1.
   
   That's it in a nutshell. I hope I didn't miss anything ( written from memory... ). If anyone has any shortcuts, or a different way, please chime in!
   
   Shawn Hamer
   Villager Omnimedia