paperclip.rb

module Paperclip
  module Dimension
    def get_size_of(name, thumbnail=nil)
      return '0x0' unless get_path_of(name, thumbnail)
      Geometry.from_file(get_path_of(name, thumbnail)).to_s
    end
    
    # calculates width using processor
    def get_width_of(name, thumbnail=nil)
      return 0 unless get_path_of(name, thumbnail)
      Geometry.from_file(get_path_of(name, thumbnail)).width.to_i
    end
    
    # calculates height using processor
    def get_height_of(name, thumbnail=nil)
      return 0 unless get_path_of(name, thumbnail)
      Geometry.from_file(get_path_of(name, thumbnail)).height.to_i
    end
    
    #path to the attachment
    def get_path_of(name, thumbnail=nil)
      attachment_for(name).path(thumbnail)
    end
  end
end

Paperclip::InstanceMethods.send(:include, Paperclip::Dimension)

Added the ability to get at the dimensions of thumbnails in addition to the original.