Tineye must take this so much further, one image I looked up was about half of one of the pictures returned, I think it was in a page of a book.
From the reddit link further down - "A Fourier transform takes a signal in the time domain and breaks it down into its frequency components. Simplified, it takes a CD and produces sheet music.", "To be clear, OP says this is a matching algorithm - it's not what tineye uses, because matching the signature from the searched-for image with the database of previous signatures which is probably a nightmare."
From the reddit link further down - "A Fourier transform takes a signal in the time domain and breaks it down into its frequency components. Simplified, it takes a CD and produces sheet music.", "To be clear, OP says this is a matching algorithm - it's not what tineye uses, because matching the signature from the searched-for image with the database of previous signatures which is probably a nightmare."