1. A method of acquiring high-resolution ultrasound images of a medium (M) using an array of N transducers (T 1 to TN) using successive transmission matrices, characterized in that it comprises the steps of: a) acquiring at least one preliminary image (ZI) of the medium (M); b) defining an area of interest (D 1 ) in the preliminary image (ZI); c) determining inter-transducer correlation matrices corresponding to the area of interest (D 1 ) and to the unwanted area; d) determining a characteristic matrix (MC) of the area of interest (D 1 ) resulting from the product of the inverse of the inter-transducer correlation matrix of the unwanted area by the inter-transducer correlation matrix of the area of interest (D 1 ); e) calculating eigenvectors and eigenvalues of the characteristic matrix (MC) of the area of interest (D 1 ), these vectors, classified as a function of their corresponding eigenvalues, defining a transmission matrix; f) selecting the K eigenvectors associated with the K highest eigenvalues from the N eigenvectors; g) firing K waves weighted by the selected K eigenvectors, each selected vector weighting the signals transmitted by the transducers (T 1 to TN) during a firing, these vectors defining a truncated transmission matrix composed of, in a first part, the K vectors of the family of eigenvectors associated with the K highest eigenvalues of the characteristic matrix and, in a second part, columns of zeros corresponding to the firings that are not effected; h) receiving the signals returned by the medium (M); i) multiplying a reception matrix constituted of the acquired signals completed by data set to zero corresponding to the firings not effected by the inverse of the transmission matrix to obtain a complete data set; j) extracting low-resolution images from the complete data set as in synthetic aperture echographic imaging methods; and k) reconstructing the high-resolution image corresponding to the area of interest (D 1 ) by coherent summing, as in synthetic aperture echographic imaging methods, of the low-resolution images extracted from the complete data set.