The British Library will soon be asking for your help. In partnership with Microsoft, the British Library has digitized thousands of out-of-copyright books from the 17th, 18th, and 19th centuries. Included within those books were maps, diagrams, illustrations, photographs, and more. The Library has uploaded more than a million of them onto Flickr and released them to the public domain. However, the majority of the million picture collection is uncatalogued, its subject matter unknown.
To be sure, the collection does list the title of each book from which a picture, illustration, or map was extracted. However, most of these images are listed without any description other than what may be found in adjacent pages. Of course, a human can read those pages and even a computer can do so using OCR technology. However, no computer can isolate and extract the descriptions of the images from a printed page.
The Library plans to launch a crowdsourced application to enable humans to describe the images. Each person presumably will need to look at assigned images one at a time, read a page or two of text published before and after each image, then write a description of that single image. This information will then be used to train an automated classifier that will be run against the entire corpus.
The call for volunteers will probably appear sometime in 2014, after planners determine for contents and format of the tagging and metadata information. The crowdsourcing management software also needs to be written.
You can view many of the images now by starting at http://www.flickr.com/photos/britishlibrary.