The light stream Lumen [lm] is a photometric unit, which means that it is measured in the wavelength range of visible light (380 bis 780 nm). Photometry does not investigate the physical connections but instead is based on the sensitivity of the human eye. For projectors or video projectors, the light beam is measured in ANSI Lumen. ANSI (American National Standards Institute) is an old norm for establishing the beam of light used in projectors.
Interestingly, this norm has not been valid since 2003 – i.e. the current details are no longer valid. The reason for this is that the maximum settings appropriate for the norm are almost never relevant because they are unusable. If the settings are optimized, the light beams are usually below it.
In order to measure the light beam according to the norm, new measurements are made on the projection surface and the values of the illumination strength are measured in order to obtain an average value which is multiplied by the surface of the image ( Lumen = Lux * m²).
As in the LCD sector, where it is popular to advertise with huge contrast values, it is not possible ti imagine much based on the number of the ANSI Lumen value except that the image becomes brighter the higher the ANSI Lumen rating. For example, a 100 watt light bulb has an ANSI Lumen rating of 1500 lm. The light supply is the ratio of light beam to power consumption, which is why it is 15 lm/W in our example. The rest of the energy is lost through head and invisible projection.