colors.rb

require 'digest/sha1'

0.upto(1000).each do |i|
  s = i.to_s
  digest = Digest::SHA1.hexdigest(s)
  fg = digest[0..5]

  fg_     = {}
  fg_[:r] = fg[0..1]
  fg_[:g] = fg[2..3]
  fg_[:b] = fg[4..5]

  bg_ = {}
  bg  = ''
  # maximize contrast
  delta = 0x80

  [:r, :g, :b].each do |component|
    level = fg_[component].to_i(16)
    bg_level = level + delta
    bg_[component] = '%02x' % (bg_level % 0x100)
    bg << bg_[component]
  end

  print %Q{<span style="display:inline-block; width:5ex; font-weight: bold; color:##{fg}; background:##{bg}; text-align:right;padding-right:0.2ex;">#{s}</span>}
end