Find images that aren't referenced at all in a folder's code

gistfile1.rb

`find /Users/tyson/project/images/`.split("\n").each do |path|
  file = path.split("/").last
  next if file.empty? || file == ".DS_Store"
  result = `ack '#{file.gsub(".", "\\.")}' /Users/tyson/project`
  puts path if result.empty?
end

Thought I could do this with a pithy one-liner shell script. Alas, it was beyond me.