ANSI lumens is a unit of measurement that shows how strong or intense a light source is, specifically in projectors. It is defined by the American National Standards Institute (ANSI) and is the standard measurement of projector brightness. The ANSI Lumens Measurement Method involves many variables and is more complicated than measuring lumens. It takes the average of nine different measurement points on the screen to provide a more accurate value. The factors that affect ANSI Lumens in a projector include lamp brightness, projector optics, screen size and distance, ambient light, and color and contrast. ANSI Lumens is an essential measurement in projectors that determines how bright the image will appear on the screen.