Abstract: A method of lens position determination in an imaging system is disclosed. The system can include an imaging lens, an image sensor, and an optical encoder interposed between the imaging lens and the image sensor. The method can include capturing image data from a scene by detecting, with the array of pixels of the image sensor, light incident from the scene having passed through the imaging lens and the encoder, the encoder being configured to encode angle-dependent information about the incident light in the image data in accordance with an angular response of the encoder. The method can also include generating a uniform-field image from the captured image data, the uniform-field image having an intensity profile that varies with image position in accordance with the encoded angle-dependent information. The method can further include determining current lens position information about the imaging lens from the intensity profile of the uniform-field image.

Abstract: A method and system for searching databases having items indexed by multiple keywords that are indicative of the item being indexed for easy searching by having keyword lists that reference lists of items that fall under these specific keywords. These keyword lists reference item lists that indicate which item is under which keyword and how this item can be found in a database. The keyword lists are advantageously searched by storing them in a word tree where each node in the word tree is an element of a keyword. By traversing the word tree to arrive at a bottom node or at an intermediary node from which bottom nodes derive, partial and full keyword searches are performed. These keyword lists and their corresponding item lists are able to be cached at a user computer from which the user performs his or her search. Any items that match the search terms entered by the user can then be retrieved from a remote server.