[unilynx]

You can't easily use that with a plain* CDN though - you would need to add a Vary: Accept header and cache misses will increase as every variant of Accept: will cache a different version

* it seems fixable with things like Lambda@Edge and I wouldn't be surprised if a smart CDN which already does on-the-fly image compression had implemented this too

[selcuka]

You can't parse the User-Agent header (which is the suggested method in the article) with a plain CDN either, so that argument is moot.