How does a movie projector show black?

Courtesy of Rhett Allen

But what about the colors from the video display device? It basically does the same thing. However, instead of an array of small RGB LEDs, it projects RGB colors to different locations on the screen.

Highlight the black color

Now we’re ready for the fun stuff. How does a video projector emit black light? The black light will be the absence any Light as we have seen before. How can you not expect anything? First, let’s think of a screen like a television. If you have three small lights (red, green, blue), you can create a small black spot by simply turning off the lights for all three colors in that spot. Boom, it’s black!

Is it possible to just turn off the monitor to get black? This can’t be true, right? If so, you won’t be able to tell the difference between the expected black and the screen without turning on the monitor. Yes, this is exactly how it works.

Check it out: In the next image, I’m showing a slide that’s half black and half white. The slide occupies most of the screen space.