1. A method for classifying a multimodal test object, termed a multimedia test object, described according to at least one first modality and one second modality, said method comprising: constructing a recoding matrix X of representatives of the first modality forming a dictionary of the first modality including a plurality K T of words of the first modality, wherein each of the components of the recoding matrix X forms information representative of the frequency of each word of the second modality of a dictionary of the second modality including a plurality K v of words of the second modality, for each word of the first modality, an offline construction, by unsupervised classification, of a multimedia dictionary W m , defined by a plurality K m of multimedia words, on the basis of the recoding matrix X, a classification of a multimedia test object comprising: recoding of each representative of the first modality, relating to the multimedia test object, on the multimedia dictionary W m base, and aggregating the representatives of the first modality coded in the recoding step in a single vector BoMW representative of the multimedia test object.