1. A method for converting a text sentence into an image sentence, the method comprising: receiving a text sentence comprising a plurality of words, wherein the text sentence includes a verb phrase that is associated with a semantic role; submitting a query to an image database, the image database having stored therein a plurality of candidate images, at least a portion of which are tagged with image content descriptors; making a determination that none of the candidate images in the database is tagged with an image content descriptor that corresponds to the semantic role; in response to making the determination, generating first and second sentence fragments from the text sentence, wherein each of the first and second sentence fragments is associated with a respective first and second fragmented semantic role; generating a feature vector characterizing a subset of the candidate images stored in the image database; and identifying a first particular one of the candidate images in the subset of candidate images that is characterized by features matching at least one of the first and second fragmented semantic roles.