class Magick::OptionalMethodArguments

Collects non-specific optional method arguments

def define(key, val = nil)

set(key, val) corresponds to -set option:key val 
def define(key, val = nil)
   @img.define(key, val)
end

def highlight_color=(color)

accepts Pixel object or color name 
def highlight_color=(color)
   color = @img.to_color(color) if color.respond_to?(:to_color)
   @img.define("highlight-color", color)
end

def initialize(img) 

def initialize(img)
   @img = img
end

def lowlight_color=(color)

accepts Pixel object or color name 
def lowlight_color=(color)
   color = @img.to_color(color) if color.respond_to?(:to_color)
   @img.define("lowlight-color", color)
end

def method_missing(mth, val)

miscellaneous options like -verbose 
def method_missing(mth, val)
   @img.define(mth.to_s.tr('_', '-'), val)
end