How do projectors and screens show the color black if black is the absence of light?
In: Technology
By not having any Light, on lcd screens the crystals will all block meaning very little light comes through causing an almost completely black pixel. With oled it just turns off that spot entirely, and with projectors it doesnt project or block light at that place
They don’t really. They do their best to show no light there and hope the contrast with the bright areas creates the appearance of black.
The physically darkest a screen can get is turned off, so if you just turn off your monitor you can see the blackest black it can create. This can be made darker by reducing the amount of ambient light hitting the screen, which is why if you want a good home theater experience you need to black out the room to make it as dark as possible.
They don’t, but in slightly different ways.
Projectors send an image on a reflective white screen, and for black the film is completely opaque so that no light is sent. However you have to watch in the dark so that no ambient light “lights up” the parts you want to be black.
Computer and TV screens also send light when needed, or not at all, but the default color of the material used is black to begin with, so even in a lit room, you see a black object.
There was a scam a few years ago about à glace let containing a micro projector showing a user interface on your wrist, and their prototype video showed black being projected. You simply cannot do that.
They just don’t display anything.
For a screen, which looks pretty black when turned off, works pretty well.
But for a white projector screen, the room really needs to be dark.
By either blocking the light that is being emitted (in the case of a projector or LCD screen), or by not emitting light from that pixel at all (as is the case for OLED screens).
How close this gets to a true black will vary by screen and ambient conditions. In the case of projectors in particular, they project onto a white or grey screen, and the underlying pixel cannot be any darker than when the projector is off, which is why they need darkened rooms to be particularly effective.
Human s enses are logarithmic. You don’t really see black, your eyes will see a dark gray in the absence of light (eisengrau).
You perceive black where, logarithmically, the image has less light.
This one amazed me when it got mentioned in a VT course.
The black you see is actually white.
Imagine a white wall, on which you project an Excel sheet.
White with black lines. Because you cannot project black light the best you can do is project nothing for the lines and a lot of white light for the white parts.
Now if you don’t project light on a white surface it is still white. But the rest of it is just “more” white or brighter and that makes you think it is black.
That’s why you need a really bright light or a dark room. If the light is not bright enough or if the surrounding light is brighter, you don’t get that level of contrast for your brain to make it black. Then the lines appear to be gray.
If you are thinking of movie projectors, or something that is projected on to a white screen, that is not the absence of color, that is actually all the colors projected at the same time. If you were to mix a whole bunch of different paints together and spread it on a white background it would look black. So projectors are just painting with light.
There is a whole complex theory behind this that has to do with what color actually is, how we perceive color, and how light projection works but that gets really complicated and takes a bit to wrap your head around. This gets into how projecting all the colors is really actually blocking all the colors and that what you see on a screen that is black is actually just a really dark color but not true black. Like I said it gets complicated
So If you are wondering why something projected on a screen is black, it’s really projecting all the colors.
Now modern tvs and monitors are not projecting and the science behind how they make color gets complex fast and it all depends on what method is used to display that color.
Projectors show the color black by turning off all of the lights in the room. TV screens show the color black by making the screen absorb as much light as possible. Which is why movie theaters turn off the lights when the movie starts, but you can still watch TV in a brightly lit room.
Black isn’t the absence of light, its the absorption of light, if anything, its the color with the most light
Darkness is full of light, just look at black holes
And space
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