1. A retrieval method comprising: providing a projection for embedding an original image representation in an embedding space, the original image representation being based on features extracted from the image, the projection having been learned from category-labeled training data to optimize a classification rate on the training data; and with a processor, for each of plurality of database images, computing a comparison measure between a query image and the database image, the comparison measure being computed in the embedding space, respective original image representations of the query image and the database image being embedded in the embedding space with the projection; and providing for retrieving at least one of the database images based on the comparison.