[bscphil]

Exactly. Many people are insensitive to blurring / smearing artifacts, and so what you very often see is a comparison between an old codec at a medium bitrate with noticeable artifacts (e.g. JPEG picking and ringing) and a new codec at a low bitrate with different artifacts that the author just didn't notice. It's no longer a 1:1 comparison. Is the modern codec still better? Probably, but unless the new codec is identical to the old one with less bitrate (hint: it rarely is), you can't prove it with differently sized comparison images.

[vlovich123]

It cuts both ways though which is what I’m trying to say. Humans can’t say “this artifact is 20% worse”. Everyone has a subjective opinion.

I disagree thought mostly about the codec characterization. H265/AV1 are definitely higher quality at the same bitrate. The test I used is to find the bitrate that artifacts started to be noticeable. H265 was 15-20% smaller bitrate consistently (across multiple people surveyed, not just me). I could definitely believe that AV1 manages a similar feat above that.