Dragonfly is a framework that enables on-the-fly processing for any content type.
It is especially suited to image handling. Its uses range from image thumbnails to standard attachments to on-demand text generation.
simple-image-uploader creates Image scaffold with file upload and removal. It is based on carrierwave and mini-imagegick gems. Image model, controller and form are have simple code that allows any application to use image upload immediately. Add simple-image-uploader gem to your Gemfile. Run bundle install. Then run 'rails g simple_image_uploader'. Run rails s and check http://localhost:3000/images.