5. A method comprising: obtaining a query image; generating a high-dimensional generative representation of low-level features the query image; generating a lower-dimensional representation of the low-level features of the query image based on the high-dimensional generative representation; and generating a comparison score for the query image and a reference image based on the lower-dimensional representation of the query image and on a combined representation of the reference image, wherein the combined representation of the reference image includes one or more classifiers and a lower-dimensional representation of the reference image, and wherein the combined representation of the reference image was generated according to 
 {tilde over (x)} ij =λ·w i +(1−λ)· x ij , where x ij is the lower-dimensional representation of the reference image, where w i is a respective classifier of a label that is associated with the reference image, and where λ is a weighting parameter.
5. A method comprising: obtaining a query image; generating a high-dimensional generative representation of low-level features the query image; generating a lower-dimensional representation of the low-level features of the query image based on the high-dimensional generative representation; and generating a comparison score for the query image and a reference image based on the lower-dimensional representation of the query image and on a combined representation of the reference image, wherein the combined representation of the reference image includes one or more classifiers and a lower-dimensional representation of the reference image, and wherein the combined representation of the reference image was generated according to 
 {tilde over (x)} ij =λ·w i +(1−λ)· x ij , where x ij is the lower-dimensional representation of the reference image, where w i is a respective classifier of a label that is associated with the reference image, and where λ is a weighting parameter. 9. The method of claim 5 , wherein the comparison score is generated by a dot-product operation.