9. The system of claim 8 , wherein generating a score for each of a plurality of images comprises: identifying, from a corpus of images, an image that has not been scored using the trained image relevance model for the first query; assigning the image a relevance score specifying a measure of relevance of the image as a search result for the first query; storing the relevance score in association with a reference to the image; and iteratively repeating the identifying, assigning, and storing for one or more additional images that have not been scored using the trained image relevance model for the first query.
9. The system of claim 8 , wherein generating a score for each of a plurality of images comprises: identifying, from a corpus of images, an image that has not been scored using the trained image relevance model for the first query; assigning the image a relevance score specifying a measure of relevance of the image as a search result for the first query; storing the relevance score in association with a reference to the image; and iteratively repeating the identifying, assigning, and storing for one or more additional images that have not been scored using the trained image relevance model for the first query. 10. The system of claim 9 , wherein identifying one or more highest scoring images comprises: in response to receiving the search query, identifying the stored relevance scores for images from the corpus of images; and identifying, as search results for the search query, one or more of the images from the corpus of images having highest stored relevance scores.