The Google URLs have changed for image search; it now has the URL including &udm=2. I have decided to play with the parameter’s value.
Playing with the &udm parameter shows interesting search results categories:
https://www.google.com/search?q=boolean&udm=2 images
https://www.google.com/search?q=boolean&udm=4 perspectives (!)
https://www.google.com/search?q=boolean&udm=6 learn (!)
https://www.google.com/search?q=boolean&udm=7 video (redirects to https://www.google.com/search?q=boolean&tbm=vid)
https://www.google.com/search?q=boolean&udm=12 news (redirects to https://www.google.com/search?q=boolean&tbm=nws)
https://www.google.com/search?q=boolean&udm=14 web, no AI (!)
https://www.google.com/search?q=boolean&udm=18 forums
I do not think this is documented.
By Googling, I also discovered this interesting reading about the last “no AI” option – Wrenching Around Google URLs, Get Your Old Skool Search Back (for now).
It is fun playing with URLs. 🙂