As many will know, images of all US censuses going back to 1790 are available online http://blog.archive.org/2010/12/22/1790-1930-u-s-census-records-available-free/. Unfortunately the quality of the images is very poor in places and, as far as I know, there are no free processed versions of them available. If you take an example like the following from the 1920 census, what would be a good method to extract relatively clean images of the handwritten text from the background image and noise?
The original pdf for the page is at http://wikisend.com/download/737634/page.pdf as I don't have the reputation points to post it here yet (can someone with more rep upload it?).