def convert(f, opts = {})
      opts = opts.dup
      f = f.to_s.downcase
      allowed = %w(jpeg jpg png)
      raise ArgumentError, "Format must be one of: #{allowed.join(',')}" unless allowed.include?(f)
      self.format_override = f == 'jpeg' ? 'jpg' : f
      opts[:Q] = opts.delete(:quality) if opts.has_key?(:quality)
      write_opts.merge!(opts)
      get_image
    end
def convert(f, opts = {})
      opts = opts.dup
      f = f.to_s.downcase
      allowed = %w(jpeg jpg png)
      raise ArgumentError, "Format must be one of: #{allowed.join(',')}" unless allowed.include?(f)
      self.format_override = f == 'jpeg' ? 'jpg' : f
      opts[:Q] = opts.delete(:quality) if opts.has_key?(:quality)
      write_opts.merge!(opts)
      get_image
    end
Convert the file to a different format


 === Parameters
 [f (String)] the format for the file format (jpeg, png)
 [opts (Hash)] options to be passed to converting function (ie, :interlace => true for png)