Visual tag dictionary: interpreting tags with visual words

Visual-word based image representation has shown effectiveness in a wide variety of applications such as categorization, annotation and search. By detecting keypoints in images and treating their patterns as visual words, an image can be represented as a bag of visual words, which is analogous to the bag-of-words representation of text documents. In this paper, we introduce a corpus named visual tag dictionary. Unlike the conventional dictionaries that define terms with textual words, the visual tag dictionary interprets each tag with visual words. The dictionary is constructed in a fully automatic way by exploring the tagged image data on the Internet. With this dictionary, tags and images are connected via visual words and many applications can be thus facilitated. As examples, we empirically demonstrate the effectiveness of the dictionary in tag-based image search, tag ranking and image annotation.