How is a CRT able to display black?

MaximRecoil

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The screen of a CRT is not black when turned off (especially the older ones, which were light gray). For the RGB color model, black = zero levels of red, green, and blue, so that would mean that no electrons are exciting any phosphor when black is called for, right? Which is the same thing that happens when the monitor is turned off; so why don't you just see the gray color of the screen instead of black?

Similarly, how does a film projector display black on a white screen? Anything black on the film would be opaque, right? So if no light can pass through the black areas of the film, shouldn't that leave the screen white? Black of course, is not a color, but rather, the absence of light. Projection is a means of "throwing light". The idea of "projecting black" would seem to be oxymoronic.
 
Contrast. That's it. Compared with the illuminated areas on a CRT, the default "gray" is really really dark. Same with projection. But projectors are more like LCD displays. The default is brightest white. You have to try to prevent the light from getting through by using opaque areas. That's why most (if not all) LCDs look terrible compared with a even a mediocre CRT display. You just can't get good blacks.
 
So it is just an illusion then. I guess the idea behind the darker gray screens that started showing up in the late '80s was for better blacks in lit rooms (thus resulting in better contrast)? I suppose the same thing is accomplished with tinted plexi in front of the monitor, like some classic arcade machines had.
 
Yep, I think you got it. With the tinted overlays, I think there were a couple of goals. First was probably to add color to B&W games. Second, the tinted/smoked overlays hide small changes in intensity at the dark end. That takes care of phosphor burn. A third benefit was to hide the guts of the machine somewhat.
 
The screen of a CRT is not black when turned off (especially the older ones, which were light gray). For the RGB color model, black = zero levels of red, green, and blue, so that would mean that no electrons are exciting any phosphor when black is called for, right? Which is the same thing that happens when the monitor is turned off; so why don't you just see the gray color of the screen instead of black?

Anti-photons... miniature black holes suck all the light away.
 
You have to try to prevent the light from getting through by using opaque areas. That's why most (if not all) LCDs look terrible compared with a even a mediocre CRT display. You just can't get good blacks.
Amen to that ! My TV is still a (16:9) tube and it will be until it breaks

Something else: actually, a color raster CRT monitor is only trying to "hide" all colors when displaying black. However, the electron beam is still moving across the lines of the black area and the beams cannot be turned off completely. This results in a relatively good black (compared to LCD's) but still it is a little bit grey.

If you then compare it to a (color) vector monitor, you will see some REAL black ! The electron beam simply doesn't "touch" the parts it's not drawing anything, resulting in the deepest black you can get on a CRT. That's one of the beautiful aspects of a vector monitor. Combined with the brightness of the spots that do get struck by the beam it gives a spectacular contrast.
 
Amen to that ! My TV is still a (16:9) tube and it will be until it breaks
YEAH!!.....from my cold dead fingers, etc! :)

Something else: actually, a color raster CRT monitor is only trying to "hide" all colors when displaying black. However, the electron beam is still moving across the lines of the black area and the beams cannot be turned off completely. This results in a relatively good black (compared to LCD's) but still it is a little bit grey
Really? Are you sure it isn't just incorrectly setup? Not disagreeing with you, I'm just surprised. When I set up my monitors I get superb darks/blacks. And brilliant whites.
 
And here I was under the impression that the photon is its own antiparticle.

Weird. That would explain a lot.

We should market a flashlight that only outputs anti-photons and make a FORTUNE.

RM

I think this is similar to the "portable hole" that Bugs Bunny used to use.

Those are very convenient for bank robberies, if you're locked out of the house, etc.
 
And here I was under the impression that the photon is its own antiparticle.

Weird. That would explain a lot.

We should market a flashlight that only outputs anti-photons and make a FORTUNE.

RM


been there, done that, went broke. no one wants a flashlight that doesn't flash light.

Dude, what the hell is the name of the show your Avatar is from?
 
I think this is similar to the "portable hole" that Bugs Bunny used to use.

Those are very convenient for bank robberies, if you're locked out of the house, etc.


Unfortunately I ordered the wrong "portable holes" the ones I got are fixed in size, and I can't fit through them. Makes it easy to reach into cabs though.
 

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