>>3218
>JPEG>>>gif, PNG
I find myself believing this unironically with each passing day. Especially since JPEG also supports lossless mode. And they're actually smaller than PNG (sometimes) (on why see next paragraph).

>I can barely see the images zoomed whenever I click on them
I think arithmetic coding (aka my main weapon in crushing filesize of those images) is to blame. The patents on it have only expired few years ago, so the support for it isn't yet widespread.
For example even I encounter some bugs on its way. I recompressed the image from >>3215 with arithmetic encoding, and after expanding it I see blankness. Stil works if viewed in separate tab (funnily enough, first characters of md5sum of that image spell 'bad', as you can see for yourself in the URL)
But man, is it the killer feature of the jpeg imo. The all grey 171 bytes image? 17 kilobytes with regular Huffman coding. In 90% cases it's achieves superior compression to Huffman tables.

I tried >>3215 with Huffman coding just now and it actually came out with smaller filesize than arithmetic coded one. WTF ARITHMETICBROS THIS WASN'T SUPPOSED TO HAPPEN
I guess this just goes to show that there is no golden panacea for everything