Colors.rb

# -*- coding: utf-8 -*-

class Colors
  def Colors.getArrayFromString(str, num)
    colors = str.unpack(("a" + num.to_s) * (str.length / 2))
    colors = colors.collect{|color|
      color.hex
    }  
    return colors
  end

  def Colors.getRGB2HSB(rgb)
    # #の削除
    rgb = rgb.sub(/#/, "")
    # 文字列をRGBのそれぞれに分割
    colors = getArrayFromString(rgb, 2)
    # RGB => HSB に変換する
    # Hへの変換
    h = nil
    if (colors.max - colors.min) == 0 then
      h = 0
    else
      h = (colors.max - colors[0]) / (colors.max - colors.min).to_f * 60
      + 60
    end
    # Sへの変換
    s = nil
    if colors.max == 0 then
      s = 0
    else
      s = (colors.max - colors.min) / colors.max.to_f * 255
    end
    # Bへの変換
    b = colors.max
    return [h, s, b]
  end

  def Colors.distance(color1, color2) 
    array = []
    color1.each_with_index{|v, i|
      ratio = (color1[i] - color2[i]).abs / 255.to_f
      distance = 1 - ratio 
      array.push(distance)
    }
    return array
  end

  def Colors.distanceForRGB(color1, color2) 
    return distance(getRGB2HSB(color1), getRGB2HSB(color2))
  end
end

web.rb

# -*- coding: utf-8 -*-

require './Colors'

color1 = "#FF0000"
color2 = "#0000FF"

distances = Colors.distanceForRGB(color1, color2)
p distances
puts "色の類似度:" + distances.inject(:*).to_s