Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 156-166).A picture is worth a thousand words. Images have been used extensively by us to interact with other human beings to solve certain problems, for example, showing an image of a bird to a bird expert to identify its species or giving an image of a cosmetic product to a husband to help purchase the right product. However, images have been rarely used to support similar interactions with computers. In this thesis, I present a series of useful applications for users to interact with computers using images and develop several computer vision algorith...