A chromatically non-uniform illumination device comprising: - an artificial broad-band light source (52; 60,64; 80,84) comprising a white light source or a light source with a spectral bandwidth greater than 100 nanometers in the range of wavelengths between 400 nanometers and 700 nanometers, the artificial light source comprising one or more active elements which emit photons or which absorb photons and then re-emit them at a higher wavelength; - a chromatic diffuser (56; 66; 86) located downstream the artificial light source; the chromatic diffuser is configured to not emit light and to change the propagation direction of the light emitted by the artificial light source; and wherein the chromatic diffuser comprises elements of a first non-liquid material transparent to light in the range of wavelengths between 400 nanometers and 700 nanometers and having refractive index n 1, the elements of the first non-liquid material being dispersed in a second non-liquid material transparent to light in the range of wavelengths between 400 nanometers and 700 nanometers and having refractive index n 2, wherein |n 2 /n 1 -1|>0.1 and wherein a typical linear dimension d of the dispersed elements of the first non-liquid material satisfies the condition 5nm≤d≤300nm; and wherein a maximum dimension L max of the chromatic diffuser is equal to or greater than five times the minimum dimension d min of a projection of the largest of said active elements in a first plane perpendicular to a first direction, wherein: - in case the artificial light source is anisotropic, said first direction is the maximum emission direction (I max) of said artificial light source; otherwise - in case the artificial light source is isotropic, said first direction is defined by a straight line (I prox) that joins the two closest points of said artificial light source and chromatic diffuser; and wherein said maximum dimension L max of said chromatic diffuser is defined as the greatest between: - a transverse dimension defined as the maximum distance between couples of points belonging to a projection of the chromatic diffuser on the first plane; and - a longitudinal dimension, defined as the maximum distance between couples of points belonging to a projection of the chromatic diffuser on a second plane parallel to the first direction; the chromatic diffuser being thereby configured to separate blue radiation, scattered by the chromatic diffuser, from yellow radiation, transmitted by the chromatic diffuser. - an artificial broad-band light source (52; 60,64; 80,84) comprising a white light source or a light source with a spectral bandwidth greater than 100 nanometers in the range of wavelengths between 400 nanometers and 700 nanometers, the artificial light source comprising one or more active elements which emit photons or which absorb photons and then re-emit them at a higher wavelength; - a chromatic diffuser (56; 66; 86) located downstream the artificial light source; - in case the artificial light source is anisotropic, said first direction is the maximum emission direction (I max) of said artificial light source; otherwise - in case the artificial light source is isotropic, said first direction is defined by a straight line (I prox) that joins the two closest points of said artificial light source and chromatic diffuser; - a transverse dimension defined as the maximum distance between couples of points belonging to a projection of the chromatic diffuser on the first plane; and - a longitudinal dimension, defined as the maximum distance between couples of points belonging to a projection of the chromatic diffuser on a second plane parallel to the first direction;