Plus there are 12 comments on HN mentioning this URL in 12 different discussions:
https://ampie.app/url-context?url=alvyray.com/Memos/CG/Micro..., and it has been linked from this great article on alpha compositing by Bartosz Ciechanowski (you should really check out his blog if you haven't seen it):
https://ciechanow.ski/alpha-compositing/