Abstract: The invention concerns a method of converting raw multidimensional digital data corresponding to points making up a 2D or 3D image of unknown size and an associated system. The method comprises: the sizing a multidimensional window for traversing of said image, the said sizing depending on the size of a buffer; the traversing the said image comprising the movement of the said window in the image along the axes of the image; at each position of the said window in the image: the step of acquisition and loading, in the said buffer, of the data of the part of the image defined by the window; the conversion by calculation of the multidimensional wavelet transform of the said loaded part by means of at least one compact support filter for generating low- and high-frequency coefficients; the saving of the said coefficients generated. Application to wavelet transformation synchronously with the acquisition of medical or seismic images.