1. A method for detecting captions in a document that includes text fragments and objects of interest, the method comprising: assigning a signature to each text fragment, the signature being the value for that text fragment of a text fragment representation comprising at least one text fragment attribute; identifying a caption signature as a signature assigned to a substantial number of text fragments that are near at least one object of interest in the document; and detecting one or more captions as one or more text fragments each assigned a caption signature.