What are alpha channels?
Alpha channels are used to create videos that contain elements that are partially or completely transparent. These assets are often used when compositing a video together using multiple layers. An alpha channel is an additional layer of information that assigns a transparency value to each pixel in a video which allows portions of a video’s frame to be partially or entirely transparent.
Incorporating Alpha Channels Into Your Shutterstock Portfolio.
Some codecs support alpha channels, and others don't. However, if you're creating videos with alpha channels, there's an easy way to get your content on site in a form that customers can use, regardless of filetype. To do this, you’ll have to create a matte for your video. Specifically, a luma matte using After Effects.
This process assumes you have a completed composition that features transparent elements.
First, you need to create a standard version of your video.
With your composition selected, select File > Export > Add to Render Queue.
Second, you need to create the luma matte.
To do this, follow steps 1 through 4 again. Once you’re back at the Output Module Settings menu with the correct codec, open the Channels dropdown and select Alpha. Set your destination folder and export.
Now you should have two version of your video. One version will look just the way the video did inside After Effects. The second version will look like a black and white cutout of your video; everything solid will be white, and everything transparent black. This is your luma matte.
Finally, drop the two files into any Editing software you’d like and drop the files in the timeline so the standard version first, the luma version second. Export the project as one video.
Now, when your clip is purchased, the customer can place the luma matte over the video to create a video with transparent elements.