How do projectors, project black?
I was sat in a meeting with some pretty clever people when one of them (who was clearly bored by my presentation) asked the above questions. Despite repeated internet searches to find the solution I am still stumped. Projecting no light at all would just show the wall colour (even with the contrast of the surroundings).

Could someone clever explain/solve this as it's been doing my head in.
( herd of chickens First part only £1.99 and comes with a free, Thu 20 Oct 2011, 10:18, 14 replies)

They do just show the wall colour
That's why you project onto a white screen in a darkened room.
(gordonjcp, Thu 20 Oct 2011, 10:23, closed)

but in this instance the room wasn't darkened
and the wall was white, the black image still came out as black. We even played by drawing a black and a white square next to each other. The white square was closer to the wall colour than the black.
( herd of chickens First part only £1.99 and comes with a free, Thu 20 Oct 2011, 10:28, closed)

shadows are black

(sittingduck Attention seeking, bullshitting fuck-knuckle, Thu 20 Oct 2011, 10:28, closed)

It's some kind of perception
thing.

Same as colour pictures printed in the Financial Times. The page is orange, but you can look as hard as you like, and your brain will still tell you Barack Obamas teeth are sparkly white.
(username failed moderation, Thu 20 Oct 2011, 10:29, closed)

cool
I never noticed that. Probably because I've never purchased the FT. I'm off to the newsagents to look at it. and to buy some porn
( herd of chickens First part only £1.99 and comes with a free, Thu 20 Oct 2011, 10:31, closed)

I like the cut
of your jib, sir.
(username failed moderation, Thu 20 Oct 2011, 10:32, closed)

And as proof:
www.michaelbach.de/ot/lum_adelsonCheckShadow/index.html
( flatfrog Staring vacantly into space, Thu 20 Oct 2011, 11:18, closed)

Your eyes don't exactly measure light intensity, they more measure differences in light. So when one object is a lot darker than another, it appears black.
www.popularscience.co.uk/features/feat16.htm
( The Mock Turtle ™ --- Thinks you are a cunt, on, Thu 20 Oct 2011, 10:35, closed)

Who taught you how to search the internet?
You should ask for a refund.
( scarpe We Stole Bikes, Thu 20 Oct 2011, 10:39, closed)

www.b3ta.com/questions/wearedetective/post1397118
( The Mock Turtle ™ --- Thinks you are a cunt, on, Thu 20 Oct 2011, 10:42, closed)

what's the internet?
to be fair it's not a bad statement. My first source was the internet. From here I found several different explanations.
( herd of chickens First part only £1.99 and comes with a free, Thu 20 Oct 2011, 10:45, closed)

and I also
get bored quickly so start looking at porn. Lots and lots of lovely porn
( herd of chickens First part only £1.99 and comes with a free, Thu 20 Oct 2011, 10:46, closed)

Yay porn
all is forgiven.



( The Mock Turtle ™ --- Thinks you are a cunt, on, Thu 20 Oct 2011, 10:51, closed)

It's the same way a sculpture manages to make an empty space out of pure marble.

( Ring Of Fire A petty, drooling belming butthurt retard., Thu 20 Oct 2011, 12:29, closed)