One convenient program that you may use to transform photographs into line art is Lica, which you may download from http://www.photolinedrawing.com/. It is appreciable that it allows you to also convert entire batches of documents, as well the fact that it supports complete web integration. Finally, it also allows you to edit the final output according to your needs, by deleting or adding lines. Of course, this is a simpler, and cheaper solution for this purpose. You may certainly use Adobe Photoshop for the same function. It offers considerably more complex line art options, but its license is significantly more expensive.