Fun fact! If it weren't for imgix, this plugin simply wouldn't exist. I was rebuilding a site for a client that had over 30,000 images, moving them from a custom rails based CMS to WordPress. On top of that, the design of the site was going to be changing again in the short term future, so I had to solve a lot of problems around media storage and handling with regards to WordPress. If the design was going to change in the future, requiring new image sizes to be recut and generated, doing that for 30,000 images was going to be a nightmare! But, because I knew imgix could do all of this cropping and resizing on the fly, it was just a matter of writing a plugin to get imgix integrated. And now here we are, four years later!
imgix is a real-time image processing proxy and CDN. It can resize, optimize, add filters and effects and do other amazing image processing tasks on the fly - and then deliver those processed images to your users through their blazing fast CDN.
I know that sounds like a commercial, but I don't work for imgix nor am I paid in any way by imgix. I am, however, one of their biggest cheerleaders because I think the service is so amazing and so fundamental to a scaleable WordPress stack that I can't imagine not using it on any WordPress site my clients engage me to build.