Google's book scanner apparently uses infrared to detect the orientation of the page and hence adjust for the position of the page: http://www.npr.org/blogs/lib

Google's book scanner apparently uses infrared to detect the orientation of the page and hence adjust for the position of the page: http://www.npr.org/blogs/library/2009/04/the_granting_of_patent_7508978.html http://www.npr.org/blogs/library/2009/04/the_granting_of_pat... It's unclear what the speed of the scanning device is though.