The big difference between ImageRack and most others solutions is that you pre-define the available image manipulations templates on the server side (for example a template for thumbnails, large images, iPad sizes etc.). I'm not a fan of letting the client generate multiple versions of an image by changing the URL (i.e. http://resize.ly/450x150/http://resize.ly/img/kittens/kitty-...).
Feel free to check it out: https://github.com/diarmuidie/ImageRack
The big difference between ImageRack and most others solutions is that you pre-define the available image manipulations templates on the server side (for example a template for thumbnails, large images, iPad sizes etc.). I'm not a fan of letting the client generate multiple versions of an image by changing the URL (i.e. http://resize.ly/450x150/http://resize.ly/img/kittens/kitty-...).