title: google image search: search similar images
body: <p>I want to write a mobile app which takes a picture and searches google images for similar pictures and then displays the results.</p>
  
  <p>However, with google image search I can only search for text strings, and with the search API it seems there's no possibility to search for <em>similar</em> pictures; this feature seems to be available only through the web interface.</p>
  
  <p>Any idea how I can solve this problem? </p>
  
  <p>thanks,
  Christoph</p>