1. A method of converting raw multidimensional digital data (x k ) corresponding to points (k) making up a multidimensional image including a two dimensional (2D) or three dimensional (3D) image of an unknown size, to be implemented by one or more processors, the points forming lines along axes of the multidimensional image, the method comprising: a step of sizing, via the one or more processors, a multidimensional window for traversing of the multidimensional image of unknown size, wherein the sizing depends on a size of a buffer memory; a step of traversing, via the one or more processors, the multidimensional image comprising a movement of the multidimensional window in the multidimensional image along the axes of the multidimensional image; at each position of the multidimensional window in the multidimensional image of unknown size: a step of acquiring, via the one or more processors, raw data (x k ) of a part of the multidimensional image of unknown size defined by the multidimensional window and loading the raw data (x k ) in the buffer memory; a conversion step comprising a step of calculating, via the one or more processors, a multidimensional wavelet transform of the loaded part of the multidimensional image by means of at least one compact support filter for generating low-frequency (s k ) and high-frequency (d k ) coefficients, the calculating step comprising, successively along each of the axes of the loaded part, filtering each of the lines extending along the axis; and a step of saving, via the one or more processors, the generated low-frequency (s k ) and high-frequency (d k ) coefficients.