rmagick_extract_colors.rb

require 'RMagick'
img = Magick::ImageList.new( logo )
white = 768
expected_saturation = white*0.65
colors = []
img.quantize(30).color_histogram.each{|c|
  r,g,b = [c[0].red, c[0].green, c[0].blue].map{|c| c/256 }
  soma = r + g + b

  points = 0
  points += (soma - expected_saturation).abs*3

  points += (256 - r)
  points += (256 - g)
  points += (256 - b)

  colors << [points, r, g, b]
}
cs = colors.sort_by{|c| c[0] }.map{|_,r,g,b|
  '#' + [r,g,b].map{|c| c.to_s(16).rjust(2,'0')}.join
}[0..5]