1. 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; computing a near property for each text fragment, the near property having a near value if the proximity of the text fragment to at least one object of interest in the document satisfies a near criterion and a value other than the near value otherwise; 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, the near property being used in the identifying to recognize text fragments that are near at least one object of interest in the document, wherein the identifying includes computing a signature-nearness association score for each signature indicative of a strength of association of the signature with text fragments having the near value; and detecting one or more captions as one or more text fragments each assigned a caption signature.