A decorative light bulb includes an outer surface forming a decorative shape and one or more inert gases inserted within the decorative light bulb to create ethereal electrical arcing having a first color. A sensor signal which is characteristic of a pressure in the area of a fuel injector is filtered using the two filters, which have filter characteristics that differ from one another. It is suitable for generating a collimated beam bundle as a multicolor source for use in digital image generation.