Given all of the effort spent to use Quartz's graphics operations, I was curious as to how they actually performed. I opened an account and tried out the upsampling, and was a bit disappointed.
Upsampling is a pretty unusual operation, though. A more useful comparison would be something like the common website task of scaling an image down to a thumbnail and adding a bit of sharpening and auto contrast/levels, etc.
Just FYI both of those 0x0.st images crash Chrome (Version 42.0.2311.135 (64-bit)) for me and several colleagues...
You don't even have to click the link, just simply get Chrome to load it into memory
edit: looks like something to do with Chrome's pre-fetching and https cert parsing, I think they're literally parsing the "0x0" string within the cert as a memory location
It handles image loading, unloading, and basic manipulation options.
I imagine, especially if the traffic is mainly for downsampling, it'd be sufficient. If it's not, then writing some custom code to do the image transforms on a GPU and bring them back shouldn't be that gnarly--and if you can afford to stick a shitton of macs in a data center, you can afford a graphics programmer to get that done.
http://chen.imgix.net/rose.png?w=560
What other upsamplers look like: https://github.com/haasn/mpvhq-upscalers/blob/master/Rose.md
Looking at the other operations available, I fail to see what is done better by Quartz than just by imagemagick.