When you request an image the first time the result is stored in a cache folder and all further requests use that cache. Image file updated and re-uploaded? No need to flush the cache; everything is automatically taken care of! Want to define the size of your “thumbnail” image? Want to add a “megaawesome” option so you can request images/image.png?s=megaawesome ? Want to disable arbitrary resizing (options 4 & 5)? No problem! Everything is set up in the first few lines of the code using intuitively-named variables. Works out of the box but is extremely easy to customize.