def to_f(a)
      b = []
      a.each do |n|
        b.push(n / 255.0)
      end
      return b
    end
def to_f(a)
      b = []
      a.each do |n|
        b.push(n / 255.0)
      end
      return b
    end
Convert from Fixnum (0..255) to Float (0.0..1.0)