The color gamut of a image display device is improved by the introduction of a broad band stop filter in combination with a band pass filter, a first light field and a second light field. The first light field is generated by a first and a second light source, emitting blue and green light, respectively. The second light field is generated by said second light source and a third light source emitting red light. The color gamut is improved since the band pass filter facilitates a displacement of the color point of said second light source towards shorter wavelengths, as the band pass filter transmits some of the blue light in the first light field. Similarly, a displacement towards longer wavelengths is facilitated, as the filter transmits some of the red light of said second light field. Hence, four primary colors are generated by only three light sources.