An apparatus comprising: - a scanning photographic sensor configured to be able to acquire an image, according to a given integration time of the sensor, of a scene illuminated by a source with regular light pulses, the light pulses of the source being emitted periodically according to a given period, so that when the integration time of the sensor is different from the period of the light pulses, the acquired image may have a regular succession of bands with different luminosities, said acquired image being made up of pixels of different colour components, - a processing unit configured to: - generate a signature vector representative of the regular succession of bands with different luminosities present in the image acquired by the photographic sensor, the signature vector being independent of the reflectance of the objects in the photographed scene and the light level in the scene, - determine a band frequency in the image from the generated signature vector, - determine the period of the source pulses from the determined frequency of the bands in the image, - a control unit configured to adjust the integration time of the photographic sensor so that the integration time is a multiple of the determined period of the light pulses from the source, the apparatus being characterised in that, to generate a signature vector associated with a colour component of the image, the processing unit is configured to: - for each line of said acquired image: - sum the value of the pixels of said colour component of this line so as to obtain for this line a value representative of this colour component, then - divide the value representative of this colour component by a value representative of this same colour component of an adjacent line of the image. - a scanning photographic sensor configured to be able to acquire an image, according to a given integration time of the sensor, of a scene illuminated by a source with regular light pulses, the light pulses of the source being emitted periodically according to a given period, so that when the integration time of the sensor is different from the period of the light pulses, the acquired image may have a regular succession of bands with different luminosities, said acquired image being made up of pixels of different colour components, - a processing unit configured to: - generate a signature vector representative of the regular succession of bands with different luminosities present in the image acquired by the photographic sensor, the signature vector being independent of the reflectance of the objects in the photographed scene and the light level in the scene, - determine a band frequency in the image from the generated signature vector, - determine the period of the source pulses from the determined frequency of the bands in the image, - a control unit configured to adjust the integration time of the photographic sensor so that the integration time is a multiple of the determined period of the light pulses from the source, - generate a signature vector representative of the regular succession of bands with different luminosities present in the image acquired by the photographic sensor, the signature vector being independent of the reflectance of the objects in the photographed scene and the light level in the scene, - determine a band frequency in the image from the generated signature vector, - determine the period of the source pulses from the determined frequency of the bands in the image, - a control unit configured to adjust the integration time of the photographic sensor so that the integration time is a multiple of the determined period of the light pulses from the source, - for each line of said acquired image: - sum the value of the pixels of said colour component of this line so as to obtain for this line a value representative of this colour component, then - divide the value representative of this colour component by a value representative of this same colour component of an adjacent line of the image.