@davidhund You’re exactly right. Image compression gets pretty great and it’s truly not linear. But that greatly depends on the type of image. I tried a variety of scenarios (Obama, Ronald Reagan, A cat, etc) and doubling the resolution, usually sat in the 300%+ range.
I suppose that statement could be massaged over time with more data. That would be an interesting test case to build.
re: Quality - I’ve heard musings of the “Quality Hack” that you described for serving images, but haven’t seen a blog post or demo outlying that. I’d be hesitant to give anyone a Quality: 30 graphic, but I bet it totally depends on the situation. You should write a blog post on that and teach the world, please!
I like ReSRC and Sencha.IO, but I’m hesitant to use anything that doesn’t document it’s targeting strategy (is it UA sniffing? Setting a cookie or something?). When targeting fails, it fails really bad (see Basecamp Mobile, etc). Additionally, I’m hesitant to use a 3rd party service (beyond a CDN) for something as simple as images. That said, I think a lot about dedicated “media boxes” might become a part of the frontend web stack in the future, due to the increasing complexity there.