[jug]

> Zoomed to 240% and looking at the top area

This isn't what any lossy formats are designed for.

How much do the lossy spots stick out when viewed in a cursory glance without zooming from a normal viewing distance? This is what lossy formats are designed for.

[lifthrasiir]

If that's indeed true, there is no point to compress an image that is larger than a target viewport---any larger image can be scaled down on encoding and upscaled on decoding. But all formats mentioned easily support much larger images.

[jug]

When I said "This isn't what any lossy formats are designed for", I meant on the web, which I thought was the context with the article and all. And then there is indeed little point of uploading images to a web server that is far larger than viewports.

I also still maintain that lossy formats aren't designed to manage users zooming into textures and trying to find out compression artifacts and wavelet caused softening of power lines. We have lossless compression for this and in this regard, WebP is actually surprisingly powerful, far far more so than PNG.

[lifthrasiir]

In case you didn't realize, "designed" is a very strong word. JPEG was certainly not designed for the web; the first web browsers didn't support inline images. WebP, despite of its name, is a key frame from VP8 which wasn't not exactly designed for the web; it was the latest iteration of TrueMotion codecs developed by On2 Technologies before its acquisition to Google, and while later codecs were also used in the web, they initially targeted games and later expanded to the general purpose format. AV1 and AVIF is probably the only format that can be possibly designed for the web due to their explicit goals.

And even so, it is utterly unclear to me how lossy image formats can be designed "for the web" in the way you have described. I will probably expect a good progressive decoding support and possibly animation, but that's all. Otherwise it's a good old psychovisual optimization under specific viewing conditions, and it is much debatable which viewing conditions represent the web environment.

> I also still maintain that lossy formats aren't designed to manage users zooming into textures and trying to find out compression artifacts and wavelet caused softening of power lines.

Which is a fair point but WebP at the lower quality does show significant enough artifacts visible without zoom for ordinary displays. Mobiles with higher pixel density in a constrainted form factor do matter, but you can't ignore ordinary displays in your file format solely for that reason.