1. A computer-implemented method, comprising: obtaining a user query; identifying, by one or more computers, images that have been assigned, by one or more image classification models for one or more corresponding n-grams that each match the user query, the n-gram as a text label of the image, wherein the image classification models assign n-grams as labels to images based on the images being associated with text matching the corresponding n-gram of the image classification model and a feature vector of the image; applying, by one or more computers, a boost value to a relevance score of each of at least one of the images to obtain an adjusted relevance score, wherein the boost value applied is based, at least in part, on a strength of the match between the user query and the text label of the image; ranking, by one or more computers, the images based, at least in part, on the adjusted relevance score; and outputting, by one or more computers, at least a portion of the images for presentation on a search results page responsive to the user query.