Inspired entirely by @jasonnoble, this Rack middleware recreates the upside-down-ternet described in http://www.ex-parrot.com/pete/upside-down-ternet.html.

Works just like any other middleware. Bonus: set your own image transformations!

# environment.rb
require 'rack_upside_down_ternet'
config.middleware.use Rack::UpsideDownTernet, '-blur 10'

• Uses curl instead of just grabbing the file out of the images directory
• Doesn't even kinda work with remote/absolute URL images
• Requires unicorn (or any multi-worker setup). Make sure you have at least 2 workers running, as your first request will block curl from downloading images
• Requires that you create PROJECT_DIR/tmp and PROJECT_DIR/images/mod