12. The system of claim 11 , wherein the instructions cause the one or more computers to perform operations comprising: computing a classification score for the image to the one or more candidate labels based on the feature vector and the image classification model for the n-gram matching the one or more candidate labels; and classifying the image as relevant to the one or more candidate labels based on the classification score.
13. The system of claim 12 , wherein classifying the image to the one or more candidate labels based on the classification score comprises: determining that the image has a classification score to a particular candidate label that meets or exceeds a relevance threshold; and labeling the image with a label corresponding to the particular candidate label.