1. A characterization method for characterizing a digital image in which at least one point of interest (PI) in the digital image is detected in association with a region of the image presenting high frequencies, the method being characterized by the steps of: selecting a first determined two-dimensional working region (RPI) of the image digital, of size smaller than the size of the image and containing the detected point (PI); for each (θ) of a plurality (I) of different prescribed orientations in the digital image: extracting a family ({f θ (k) (n)} 1≦k≦K ) of one-dimensional lines (f θ (k) (n)) of points from the first two-dimensional working region (RPI) along straight lines (K) having said orientation (θ); and calculating for each one-dimensional line (f θ (k) (n)) of points of the extracted family and for each sub-sampling level (s) selected from prescribed sub-sampling levels, a foveal energy signal (E θ,s (k) (n)) using foveal wavelets; and combining the foveal energy signals (E θ,s (k) (n)) on the lines and on their arguments to calculate a foveal signature (SI) depending on the orientations (θ) and the levels (s) of sub-sampling and characterizing the working region.