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Audio/Video Gear and Systems => Home Theater and Video => Topic started by: rif on 3 Jun 2022, 11:55 pm

Title: How does a UST laser projector show black or grey?
Post by: rif on 3 Jun 2022, 11:55 pm
It's projecting onto a white screen, and you can't project "dark".

It's just been bugging me, like getting a song stuck in your head.
Title: Re: How does a UST laser projector show black or grey?
Post by: Bob in St. Louis on 4 Jun 2022, 04:29 pm
Not long ago, we friended some aliens that gave us dark matter they extracted from a black hole. 
At least, that's what I read on the internet once.
Title: Re: How does a UST laser projector show black or grey?
Post by: rif on 5 Jun 2022, 11:29 pm
Not long ago, we friended some aliens that gave us dark matter they extracted from a black hole. 
At least, that's what I read on the internet once.

I would have guessed dark energy, but if you read it on the information superhighway,  it must be true.
Title: Re: How does a UST laser projector show black or grey?
Post by: Bob in St. Louis on 6 Jun 2022, 10:12 am
Black hole > Dark matter > Dark energy
I think they mine it using drained car batteries. The energy is attracted to the low state of charge and thereby captured.  :dunno:
Title: Re: How does a UST laser projector show black or grey?
Post by: rif on 6 Jun 2022, 10:48 am
But seriously, how does a projector show black on a white screen?

Anybody?
Title: Re: How does a UST laser projector show black or grey?
Post by: Bob2 on 6 Jun 2022, 10:55 am
This from How projectors work:
Black is “projected" by NOT projecting any light, mostly. The black you perceive on the darken screen surface is from the partial absence of illumination by the projector. In optical projectors the light from the projector's lamp is blocked by dark opaqueness of the film.

Title: Re: How does a UST laser projector show black or grey?
Post by: rif on 6 Jun 2022, 11:07 am
I don't know ... "film"?  And that explanation requires a trick that the mind does when viewing an image.

How would it project white text on a black background, like a chalkboard?  Or black text on a white background like a piece of paper?

Title: Re: How does a UST laser projector show black or grey?
Post by: rif on 19 Jun 2022, 03:36 pm
No one?
Title: Re: How does a UST laser projector show black or grey?
Post by: S Clark on 19 Jun 2022, 05:37 pm
It's kind of an optical illusion.    https://www.wtamu.edu/~cbaird/sq/2015/06/16/how-do-projectors-project-the-color-black/