1. A method of generating annotation tags for a digital image characterized by: maintaining a library of human-meaningful words or phrases organized as category entries according to a number of defined image description categories; receiving context metadata for the digital image that is associated with capture of the digital image; selecting particular category entries as vocabulary metadata for the digital image by mapping the context metadata into the library; generating annotation tags for the digital image by logically combining the vocabulary metadata according to a defined set of deductive logic rules that are predicated on the defined image description categories, said defined set of deductive logic rules comprising a set of conditional tests predicated on variable entries for one or more of the defined image description categories, such that said generating annotation tags for the digital image comprises substituting the category entries making up the vocabulary metadata as values for corresponding ones of the variable entries, and then logically evaluating the set of conditional tests according to the substituted category entries; determining confidence or fuzzy logic weighting values from the context metadata, said confidence or fuzzy logic weighting values numerically expressing the extents to which given ones of the substituted category entries apply to the digital image; and ranking the generated annotation tags from most likely to least likely, in terms of applicability to the digital image, according to the confidence or fuzzy logic weighting values, or incorporating the confidence or fuzzy logic weighting values into said logical evaluation of the set of conditional tests, whereby the truthfulness of each conditional evaluation depends on the confidence or fuzzy logic weighting values, such that the generated annotation tags correspond to higher-weighted category entries or combinations thereof.