Hacker News Reader

Do you mean lossless? PNGs are not lossy. A large photo with alpha channel in a lossless png could easily be 20x the size of a lossy webp

No I meant lossy. This is the library I use; https://pngquant.org/

Pre-processing does not a codec make (this is why .gif is considered lossless even though you lose all that 24-bit colour goodness)

Fair enough but it gets the job done well none the less.

PNG of course can be lossy. They aren’t great at it, but depending on the image can be good enough.