A color class to calculate the distance between 2 colors.

Color.rb

class MyColor
  attr_accessor :red, :blue, :green, :alpha
  def initialize(args)
    @red = args[:red]
    @blue = args[:blue]
    @green = args[:green]
    @alpha = args[:alpha] || 1
  end
  def distance(color)   
    red_diff = self.red - color.red
    blue_diff = self.blue - color.blue
    green_diff = self.green - color.green
    alpha_product = self.alpha * color.alpha
    (100) * Math.sqrt(((red_diff ** 2) + (blue_diff ** 2) + (green_diff ** 2)) * alpha_product/3 + (self.alpha - color.alpha) ** 2)
  end

  def distance_in_percentage(color)
    (distance(color) * 100) / 25000
  end
end


c1 = MyColor.new({red: 233, green: 233, blue: 233})
c2 = MyColor.new({red: 102, green: 102, blue: 102})
c3 = MyColor.new({red: 212, green: 212, blue: 204})
c4 = MyColor.new({red: 232, green: 232, blue: 232})
c5 = MyColor.new({red: 0, green: 0, blue: 0})

c4.distance_in_percentage(c2)

c1.distance_in_percentage(c4)