Premultiplied Alpha (2009)

Ah, premultiplied alpha! I haven't thought about that in years.

For reference, here's the original paper by Porter and Duff: https://dl.acm.org/doi/10.1145/964965.808606

See also: The Horrors of the Alpha Channel - https://www.youtube.com/watch?v=XobSAXZaKJ8