A system identifies a first document that includes a number of first images, identifies a second document that includes a number of second images, and forms a cluster based on a relationship between the first document and the second document. The system identifies a first caption associated with one of the first images, identifies a second caption associated with one of the second images, selects the one of the first images or the one of the second images as a representative image for the cluster based on the first caption or the second caption, and associates the representative image with the cluster.