Creating an Alpha Channel in AE 5.5

[Alisa Placas]

Do you mean that you have an image with a black background and you want the background to be transparent?
Or do you have an image without a background and want to make an animation with an alpha?

If your image has no background, all you have to do is place it in the timeline and render it out. In the render que, under the “Output Module,” make sure the Channels says “RGB + alpha” and the Depth says “Millions of colors + ”
The ‘default’ background color in your comp will be identified as the alpha channel and only your ‘image layer’ will appear.

If you have an image that already has a black background and you want to remove it so that it will be transparent over your video……put it in your timeline and either:

A. draw a mask around the area that you want to keep opaque. Whatever is not in the masked area will be transparent and render out with the above settings. Use the pen tool in your tool window to draw the mask. After you draw it, press “F” to open the mask feather options….you can soften the cutout of the mask by a few pixels if you wish with this.

B. Use a keying effect on your image, selecting the background color to ‘remove’ it. Fiddle with the tolerance levels to get a clean key. (this is only a good solution depending on the colors in your image and the color you want to ‘remove.’ ) Render with the above settings.

I hope I interpretted your question correctly. Let me know if I didn’t
Good luck.

[Ryan Osika]

For example, I have created some letterbox graphics, thin strips that line the top and bottom of the screen. I want to output the letterbox so that I can bring it into an editing program and lay it over video. What I meant by the black layer is the space between the upper and lower graphic strips that form the letterbox. Right now, they are only a black solid. That black solid is where I hope to see the video once I bring it into an editing program. So, how do I make that black solid layer transparant? Does that make sense? Thanks again.

Ryan

[Alisa Placas]

Put your letterbox graphic in the timeline.
Take the square tool from your tools palette and draw a rectangle around the portion you want to remain visible. This is a mask. The black bars are now invisible.

Either under the composition pulldown menu or by pushing Shift+Cmd+B (i think), you can change your background color. Change it to something other than black. This will allow you to see if you’ve drawn the box properly and have removed all of the black in the letter box area.

With that layer selected, press “F” to open the feather options. Try giving the mask a feather of 1 pixel. This is just to slightly soften the line.

If you want, change the background color back to black.
Render your timeline out. Keep in mind that only certain codecs will support an alpha channel. Quicktime’s Animation codec is a safe one to use if you are unsure. You can select this under the “Output Module” in the render que.
The “Format” should be Quicktime. Then, click on the quicktime button and you will get a second pop up menu with a pulldown list of possible codecs. Look for animation. A setting of High should be sufficient. Close that menu.
Under “Channels,” make sure you select RGB + Alpha. The “Depth” should then say “millions of colors +”

If you ever want to doublecheck that an animation has an alpha, open the rendered movie in quicktime and press “Cmd + I”. This gives you the movie info. Click the triangle for “more info.”
Under Format, it will say “Millions of Colors +” if it has an alpha channel.

When you import it into your editing application, be sure you have your settings set up for importing with an alpha.

Are you just laying still letterboxed graphics over the video? Or are you somehow animating the graphics in after effects that you had already made?

[Ryan Osika]

The reason I don’t think the square mask won’t work is that at one point, a graphic flies across the entire screen. Thus, I would like, if possible, to bring the animation into my editing program and have the letter box and graphics animate over my video. Again, thanks so much.

Ryan

[Alisa Placas]

I guess I’m not understanding WHAT you graphic actually is.
Are you creating something in after effects and animating it onscreen?
Or is it a pict file or a jpeg that you’ve imported and are animating in after effects?

Is it one item that you set keyframes so it moves across screen?
Or did you create a series of graphics (like a flipbook) and you just play one after another to create the appearance that it is moving?

The easiest way to do any of it is to create your object in Photoshop on its own layer and import just that layer. Animate it in your time line and unless you physically put a background in place in your comp, then no background actually exists and you can render it out with an alpha channel.

Are your letterboxed top and bottom supposed to be transparent over the video….or is that what you want to be opaque so that you are actually creating a letterbox look OVER your video?

sorry if we are confusing each other!
you can call if it would be easier to explain. 978-369-3268

[Ryan Osika]

I actually have many different layers animated using keyframes and zaxwerks 3D. If I leave the background blank, meaning no solid color in the background and I render the timeline out as an animation, will I then be able to lay that animation over video in an editing program and see the video where the blank background once was? I may just try that and see, but does what I’m saying make sense. Thank you very much for your help and your patience.

Ryan

[Alisa Placas]

yes, yes. Exactly!
Just make sure when you render, you pick the preset “Lossless with Alpha” from the Output Module pulldown menu in your render que.
After selecting it, if you click on it, it opens a window for its settings. You’ll see that the Channels is set to “RGB + Alpha”. If you click on Format Options, you can set the quality of your animation codec. “Lossless” is the Animation codec and it is…..lossless……so it makes a BIG file. You may be able to bring down the quality to High instead of Best if you wish.

Alisa