An electronic document, such as an image and a text file for example, may be associated with an action by (1) electronically extracting within a client device features from the electronic document work, (2) transmitting the extracted features from the client device to one or more servers, (3) receiving at the client device from the one or more servers an identification of the electronic document work based on the extracted features, wherein the identification is based on a sub-linear search (or wherein the identification is based on a non-exhaustive search identifying a neighbor), (4) electronically determining an action based on the identification of the electronic document work, and (5) electronically performing the action on the client device.