gistfile1.rb

has_attachment  :content_type => :image,
                :max_size     => 5.megabytes,
                :resize_to    => '800x800>',
                :storage      => :s3,
                :s3_access    => :authenticated_read,
                :thumbnails   => {
                  :thumb      => '100x100>',
                  :small      => '168x168>',
                  :mid        => '400x400>'
                }