Magick::OptionalMethodArguments

      # File lib/RMagick.rb, line 1909
1909:     def initialize(img)
1910:        @img = img
1911:     end

      # File lib/RMagick.rb, line 1919
1919:     def define(key, val = nil)
1920:        @img.define(key, val)
1921:     end

      # File lib/RMagick.rb, line 1924
1924:     def highlight_color=(color)
1925:        color = @img.to_color(color) if color.respond_to?(:to_color)
1926:        @img.define("highlight-color", color)
1927:     end

      # File lib/RMagick.rb, line 1930
1930:     def lowlight_color=(color)
1931:        color = @img.to_color(color) if color.respond_to?(:to_color)
1932:        @img.define("lowlight-color", color)
1933:     end

      # File lib/RMagick.rb, line 1914
1914:     def method_missing(mth, val)
1915:        @img.define(mth.to_s.tr('_', '-'), val)
1916:     end