16. The system of claim 15 , wherein identifying one or more entity images based on the advertising entity comprises: providing the advertising entity as a query to an image search engine; receiving, from the image search engine, data identifying images responsive to the query, the images being ranked according to an order of relevance to the query; and selecting images that are the highest ranked in the order as the entity images.
16. The system of claim 15 , wherein identifying one or more entity images based on the advertising entity comprises: providing the advertising entity as a query to an image search engine; receiving, from the image search engine, data identifying images responsive to the query, the images being ranked according to an order of relevance to the query; and selecting images that are the highest ranked in the order as the entity images. 17. The system of claim 16 , wherein determining an advertising entity for the textual advertisement comprises selecting keywords from the textual advertisement, each keyword specifying one of a product or service described in the textual advertisement.