13. A computer-implemented method, comprising: determining a plurality of semantic category scores for a digital image via application of a corresponding plurality of classifiers; and automatically determining a semantic category profile for the image based on the plurality of semantic category scores, wherein the semantic category profile characterizes semantic content of the image, and is useable to perform semantic based operations with respect to the image; analyzing a plurality of semantic categories with respect to a plurality of digital images based on one or more criteria, wherein the one or more criteria comprise at least one of: relevance of each of the semantic categories; consistency with human based classification; or accuracy of each of the semantic categories; and automatically performing: determining a subset of the semantic categories that efficiently spans the semantic content of the plurality of digital images based on said analyzing; or ranking the plurality of sets of semantic categories based on said analyzing.
13. A computer-implemented method, comprising: determining a plurality of semantic category scores for a digital image via application of a corresponding plurality of classifiers; and automatically determining a semantic category profile for the image based on the plurality of semantic category scores, wherein the semantic category profile characterizes semantic content of the image, and is useable to perform semantic based operations with respect to the image; analyzing a plurality of semantic categories with respect to a plurality of digital images based on one or more criteria, wherein the one or more criteria comprise at least one of: relevance of each of the semantic categories; consistency with human based classification; or accuracy of each of the semantic categories; and automatically performing: determining a subset of the semantic categories that efficiently spans the semantic content of the plurality of digital images based on said analyzing; or ranking the plurality of sets of semantic categories based on said analyzing. 19. The method of claim 13 , wherein the digital image is comprised in the plurality of digital images, the method further comprising: automatically determining a respective value of a semantic similarity measure for each digital image of at least a subset of the plurality of digital images with respect to the first digital image based on the semantic category profile of the first digital image and semantic category profiles of each digital image of the at least a subset of the plurality of digital images, wherein each digital image of the at least a subset of the plurality of digital images has one or more respective keywords; and automatically determining one or more keywords from the respective keywords for association with the first digital image based on the values of the semantic similarity measure.