Method for processing images using a device comprising at least one case comprising at least one first image sensor capable of covering a first spectral range and at least one second image sensor capable of covering a second spectral range, different from the first spectral range, the first and second sensor being capable of forming images of the same zone of space, the first sensor being capable of covering a spectral range belonging to the range of the wavelengths of the visible spectrum, the second sensor being capable of covering a second spectral range belonging to the range of the infrared wavelengths, the method involving: a) acquiring a first image I 1 of said given zone of space using the first image sensor, b) acquiring a second image I 2 of said given zone of space using the second image sensor, c) carrying out a decomposition of the first image I 1 so as to obtain at least one image of luminance I 1 L, d) obtaining an image I f resulting from the digital fusion of the image of luminance I 1 L and of the second image I 2, e) adding a piece of information on colour to the fusion image I f, said method being characterised in that the digital fusion involves: - carrying out decompositions, respectively noted as F n 1 F and F n 2, into successive spatial frequencies n of the image of luminance I 1 L, and of the second image I 2, - carrying out a calculation of energy in at least some zones of the images F n 1 L, F n 2 each associated with a frequency component n, - calculating a weighting image P n 1 L, P n 2, for each of the images F n 1 L, F n 2 associated with a frequency component n, from the local analysis carried out in the previous step, - for each image F n 1 L, F n 2 associated with a frequency component carrying out the following calculation: F ′ n x y = P n 1 L x y ⋅ F n 1L x y + P n 2 x y ⋅ F n 2 x y - carrying out a recombination of all the images F' n each associated with a frequency component n so as to obtain a fused image I f of all the spatial frequencies. a) acquiring a first image I 1 of said given zone of space using the first image sensor, b) acquiring a second image I 2 of said given zone of space using the second image sensor, c) carrying out a decomposition of the first image I 1 so as to obtain at least one image of luminance I 1 L, d) obtaining an image I f resulting from the digital fusion of the image of luminance I 1 L and of the second image I 2, e) adding a piece of information on colour to the fusion image I f, - carrying out decompositions, respectively noted as F n 1 F and F n 2, into successive spatial frequencies n of the image of luminance I 1 L, and of the second image I 2, - carrying out a calculation of energy in at least some zones of the images F n 1 L, F n 2 each associated with a frequency component n, - calculating a weighting image P n 1 L, P n 2, for each of the images F n 1 L, F n 2 associated with a frequency component n, from the local analysis carried out in the previous step, - for each image F n 1 L, F n 2 associated with a frequency component carrying out the following calculation: F ′ n x y = P n 1 L x y ⋅ F n 1L x y + P n 2 x y ⋅ F n 2 x y - carrying out a recombination of all the images F' n each associated with a frequency component n so as to obtain a fused image I f of all the spatial frequencies.