Get the greatest possible versatility from your still image or footage with a transparent background. Here's how to use the alpha channel in After Effects.
If you've never heard of the alpha channel before, don't worry. Everyone knows what it is – even the people who think they don't.
What is Alpha Channel?
Before touching Photoshop or Premiere Pro, I used PowerPoint for school projects. I was amazed that when I dragged an image into the software, the white background disappeared.
This disappearing background is known as the alpha channel or transparency. You'll want this when you need to overlay graphics on top of other media files. When you have a logo with transparency you can put it on top of anything you want.
I always use the alpha channel in After Effects. Without them, graphics that go beyond video – lower thirds, accented graphics, etc. – would have to be rendered to their exact composition dimensions. If you don't render the alpha channel, After Effects fills the blank area with black.
How do you render with transparency?
First, check out how much of your composition is transparent. Find the transparency grid under your main composition and toggle it on and off. Do you see gray and white checkered patterns? These are your transparent places. Turning this grid on and off does not affect the final rendering. You can only preview the final product.
Step 1: render queue
To render a video with transparency, you must first add it to the render queue. So under composition, click Add to the render queue.
Step 2: lossless
Then navigate to and click Lossless. A window called Settings of the output module will appear.
Step 3: output module settings
Here you can change the codec, color depth, format and channel. For the sake of transparency, you should be in the animation codec (or another one that allows the alpha channel to be exported). Note that some codecs do not support transparency or RGB + alpha. There's a red, green, and blue channel, then the fourth invisible channel, the alpha channel. Transparency is the alpha channel. Once you've chosen the right combination of channels for your video, you should be able to render it well.
RGB + alpha
I like to use transparency when exporting lower thirds. If I correctly position the bottom third in a 4K composition, I'll just export the entire 4K video with the RGB and alpha channels.
That way I can drag and drop the entire video into Premiere Pro without having to change its position. Of course, you don't have to render the alpha channel on all projects, but it is important to know what the alpha channel is and how it is used.
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