Representing Topics Using Images

Nikolaos Aletras and Mark Stevenson

Topics generated automatically, e.g. using LDA, are now widely used in Computational Linguistics. Topics are normally represented as a set of keywords, often the $n$ terms in a topic with the highest marginal probabilities. We introduce an alternative approach in which topics are represented using images. Candidate images for each topic are retrieved from the web by querying a search engine using the top $n$ terms. The most suitable image is selected from this set using a graph-based algorithm which makes use of textual information from the metadata associated with each image and features extracted from the images themselves. We show that the proposed approach significantly outperforms several baselines and can provide images that are useful to represent a topic.