19. The non-transitory computer-readable medium of claim 16 , wherein the instructions to classify each event comprises instructions to calculate a subject distance for each image in an event within the hierarchical event representation, wherein the classifying each event is based upon the subject distances.
16. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising: instructions to generate an event representation of an image collection; instructions to compute global time-based features for each event within a hierarchical event representation; instructions to compute image-level content-based features for each image in an event within the hierarchical event representation; instructions to combine image-level content-based features for each image in an event to generate event-level content-based features; instructions to classify, using time-based features including at least one of a duration of event, inter-event duration, or number of images in the event and event-level content-based features, each event into a category from a pre-determined set of top-level event categories; instructions to validate, using a rule-based system, each event belongs to an associated category based on the event-level content-based features; and instructions to refine the category of at least one event into a sub-category based on the event-level content-based features.