Keyword Spotting and Retrieval of Document Images Captured by a Digital Camera

This paper presents a keyword spotting technique that locates keywords within document images captured by a digital camera. In the proposed technique, the shape of word images in perspective view is captured by using three perspective invariants, namely, holes, water reservoirs, and character ascenders and descenders. Given a camera im- age of document, text line and word images are first seg- mented through the connected component analysis. The three perspective invariants are then detected through two rounds of scanning process, which transliterate each char- acter image into a character shape code of dimension six and so convert each word image into a word shape code.