[notlisted]

Suspect that in-browser sharpening of resized images (CSS or HTML) can make up for some of the detail lost in the lower JPG quality.

In the 60-90 range, differences are always minimal, especially when applied to images lacking detail 'coverage' to begin with (like the test set on the site).

Bottom line: I to think that the blogger is onto something.

Even if the "less than original size" thing doesn't always pan out due to inefficiencies in his compression process, it makes sense that in-browser sharpening would allow reduced file sizes for images displayed at lower than native resolution.

PS Significant savings in JPEG size with barely any perceptible loss of detail can be achieved by anyone with JPEGMini (which, unlike JPEG2000 is 100% compatible with all browsers these days).