8. The computer-implemented method of claim 6 , wherein determining, for each visual word and based at least in part on the respective second count for the visual word, the respective second probability that the term is not associated with the visual word further comprises: determining the second probability based at least in part on dividing the respective second count for the visual word by a number of pairwise comparisons for determining the respective second count between images in the first set of images and images in the second set of images.
6. The computer-implemented method of claim 5 , wherein determining the set of visual words from the visual words further comprises: determining a respective first count for each visual word that co-occurs in the first set of images, wherein each co-occurrence is determined based on a pairwise comparison between images in the first set of images; determining a respective second count for each visual word that co-occurs in the second set of images, wherein each co-occurrence is determined based on a pairwise comparison between images in the first set of images and images in the second set of images; determining, for each visual word and based at least in part on the respective first count for the visual word, a respective first probability that the term is associated with the visual word; determining, for each visual word and based at least in part on the respective second count for the visual word, a respective second probability that the term is not associated with the visual word; and determining a respective likelihood that the term is associated with the visual word based at least in part on the first probability and the second probability.