# File lib/dragonfly/image_magick/processors/convert.rb, line 6
        def call(content, args='', opts={})
          convert_command = content.env[:convert_command] || 'convert'
          format = opts['format']

          input_args = opts['input_args'] if opts['input_args']
          delegate_string = "#{opts['delegate']}:" if opts['delegate']
          frame_string = "[#{opts['frame']}]" if opts['frame']

          content.shell_update :ext => format do |old_path, new_path|
            "#{convert_command} #{input_args} #{delegate_string}#{old_path}#{frame_string} #{args} #{new_path}"
          end

          if format
            content.meta['format'] = format.to_s
            content.ext = format
            content.meta['mime_type'] = nil # don't need it as we have ext now
          end
        end