After Effects Premultiplied Alpha. Utilisation de l'option Prémultiplier alpha dans VRED Images with premultiplied alpha will look correct, even when the alpha-channel is ignored (or not supported by early-day applications). Adobe Premiere Pro and After Effects recognize both straight and premultiplied channels, but only the first alpha channel they encounter in a file containing multiple alpha channels.
Premultiplied vs Straight Alpha Apple Community from discussions.apple.com
In short, premultiplied alphas define the semi-transparent areas (your anti-aliased edges) by determining what your object would look like semi-transparent over a black background* In After Effects, for example, you might have your background set to blue, despite it being transparent.
Premultiplied vs Straight Alpha Apple Community
With straight (or unmatted) channels, transparency information is stored only in the alpha channel, not in any of the visible color channels. In short, premultiplied alphas define the semi-transparent areas (your anti-aliased edges) by determining what your object would look like semi-transparent over a black background* In After Effects you Interpret the footage on import and set the Premultiplied - Matted With Color picker to White
Difference Between Straight Alpha VS Premultiplied Alpha in After Effects YouTube. The oversimplified answer about what to use is that straight channels are better but premultiplied channels are compatible with more software. After Effects Help explains Alpha channel interpretation: premultiplied or straight
La couche Alpha dans After effects YouTube. Straight alpha channels, which are optimal, are purely defined by a level of transparency, without "premultiplying" it to any specific color. Adobe Premiere Pro and After Effects recognize both straight and premultiplied channels, but only the first alpha channel they encounter in a file containing multiple alpha channels.