The invention relates to a method for processing the three-dimensional digital image of the surface of a tyre, in which: the three-dimensional image of the surface is captured and each point of the acquired image is assigned a grey scale value corresponding to the elevation thereof; a first closing-type transformation of the image of the surface is performed with the aid of a first morphological operator using a rectangular structuring element; a second opening-type transformation of the surface is performed with the aid of a second morphological operator using a rectangular structuring element; and each point of the image is assigned a grey scale value equal to the minimum value between the grey scale value at this point in the image obtained in the preceding step and the grey scale value at this point in the acquired image, such as to eliminate false measurement points.