alt Hacker NewsLossless means "is identical".
The other two are variations of lossy.
Calling one of them "perceptually lossless" is cheating, to the disadvantage of algorithms that honestly advertise themselves as lossy while still achieving "looks identical" compression.
Replies
TeMPOraL • 11/08/2024
I honestly don't notice this anymore. Advertisers have been using such language since time immemorial, to the point it's pretty much a rule that an adjective with a qualifier means "not actually ${adjective}, but kind of like it in ${specific circumstances}". So "perceptually lossless" just means "not actually lossless, except you couldn't tell it from truly lossless just by looking".
It's a well established term, though. It's been used in academic works for a long time (since at least 1970), and it's basically another term for the notion of "transparency" as it relates to data compression.