Yes, thank you for pointing this out. To be more precise about it:
Original PNG: 1310987 bytes
Lossy PNG: 1154386 bytes (90.4% of LZ4i)
Lossy LZ4i: 1276477 bytes
More Lossy PNG: 693278 bytes
More Lossy LZ4i: 818774 bytes (84.7% of LZ4i)
So it's notable that this lossy PNG technique has diminishing returns for LZ4i - it actually becomes more effective as a PNG preprocessor as you get more lossy, relative to LZ4i!
Still, there's a decent argument that PNG is no longer Pareto-optimal. There's stuff that gets close to the same compression ratio but decompresses much faster, and there's stuff that compresses much better and is also lossless, e.g. JPEG-XL lossless mode.
Still, there's a decent argument that PNG is no longer Pareto-optimal. There's stuff that gets close to the same compression ratio but decompresses much faster, and there's stuff that compresses much better and is also lossless, e.g. JPEG-XL lossless mode.