8. The attribute-assigning image-processing system of claim 1 , wherein the probability returned by an aggregate classifier that returns one of two attribute values x and y is computed from a first probability distribution generated from results of applying the aggregate classifier to a set of test normalized regions known to have the attribute value x and from a second probability distribution generated from results of applying the classifier to a set of test normalized regions known to have the attribute value y.
8. The attribute-assigning image-processing system of claim 1 , wherein the probability returned by an aggregate classifier that returns one of two attribute values x and y is computed from a first probability distribution generated from results of applying the aggregate classifier to a set of test normalized regions known to have the attribute value x and from a second probability distribution generated from results of applying the classifier to a set of test normalized regions known to have the attribute value y. 9. The attribute-assigning image-processing system of claim 8 wherein the first probability distribution for the test normalized regions known to have the attribute value x is obtained from a tabulation of the number the number of component classifiers of the aggregate classifier returning the attribute value x for each test normalized regions to have the attribute value x and the second probability distribution for the test normalized regions known to have the attribute value y is obtained from a tabulation of the number the number of component classifiers of the aggregate classifier returning the attribute value y for each test normalized regions to have the attribute value y.