A method comprises at least the following steps: a step of acquiring data by radar to obtain an SAR image covering a given geographical domain; a step of acquiring at least one secondary image covering the domain, produced by a source external to the radar, the image supplying information on the colors of the constituent elements of the SAR image; a step of superimposing the SAR image and the secondary image; a step of assigning colors to the elements on the basis of their position in the superimposed secondary image.