1. A processing method for a digital image to be processed, representing a scene, the digital image to be processed being acquired using a digital capturing apparatus comprising a sensor and an optical system, the digital image to be processed being a superposition of several color channels, the method comprising: predetermining, using a processor, as a function of asymmetries in a physical constitution of the sensor, for a predetermined number of illuminant types, relative illumination modification parameters dependent on a position of pixels within the sensor; accessing the relative illumination modification parameters for each of the predetermined illuminant types that have been stored in memory including at least first illumination modification parameters for a first illuminant type and second illumination modification parameters for a second illuminant type; determining an illuminant of the represented scene on the acquired image to be processed by application of a white balance estimation algorithm; selecting, via the processor, one of the first illumination modification parameters and the second illumination modification parameters that is commensurate with the illuminant that has been determined; and modifying, on the acquired image to be processed, a relative illumination by multiplication by pixel values of the first illumination modification parameters or the second illumination modification parameters that is selected according to the illuminant, the modifying being dependent on a position of pixels within the image.