element2001 : An electron gun!!! *lol* My memory is so bad sometimes! When I was writing that message earlier today I was sitting there trying to recall all the information I could , but all I could think of was ''cathode rays'' (Duh!) when I was describing how the phosphors are lit up - Too early in the day, that''s what I put it down to ;-) Or maybe I was all thunked out from college *g* (Though I didn''t know about the electromagnets guiding the electrons)

But what''s ironic is that after all that... After making a fool of myself and blathering on about unimportant information I don''t really know all that much about, it was just the fact that his monitor was bust!!!

I don''t think you made a fool of yourself TheGilb. I would have given him the same advice at first not knowing the monitor was at fault. You''d think it would be easy to tell the monitor is the problem because everything else it displays would be off color too!

It just seemed like you needed a reminder and I hate when things are on the tip of my tongue and I can''t remember the details so I didn''t want you to go on trying to figure it out or have to look it up so I felt I just had to remind you.

Incidentally cathode stands for negative and electrons are negatively charged which is why it''s called a cathode ray tube.

Is this some sort of joke?

quote:Original post by TheGilb
Basically, your CRT or LSD monitor is comprised of coloured phosphors, it''s the same in a TV - go up real close to the TV and have a look, there are red, green and blue phosphors. When these phosphors are hit by something in the monitor (I''m not afraid to admit it, I don''t know -exactly- how it works :-)) these phosphors light up.

What exactly do you mean by an LSD (heh) monitor and where can i get one if it means what i interpret it as????????

hah I noticed that to and forgot to comment, LSD monitor lol. I think that basically that means if you do enough LSD you don''t need a monitor, just hallucinate the images in your head lol.

Either that or he meant LCD? nah i''ll go with the former it sounds more umm interesting.

Gee i wonder what the framerate is and how many polygons you can render in an LSD hallucination? hehe

The other interesting thing is why you''re taught that red, blue and yellow are the primary colors in elementary but red, green and blue in televisions and other projective devices. The answer? Light.

Light is an electromagnetic wave (it''s also corpuscular, but that''s a whole ''nother thread...) meaning it has a wavelength and frequency and all that good radio-type stuff. The colors we see from looking at things are what they reflect from the original light source (usually the sun). Wood, for example, absorbs all frequencies except for those shades of brown, orange-ish and yellow-ish that we recognize as particular types of wood. If you send two EM signals (waves) along an identical path, they interfere. If the amplitudes of the waves are equal in magnitude and opposite in sign at certain points, the waves cancel at those points. That''s how blue and green light produce yellow (the waves cancel each other partially, and what''s left is the yellow wavelength.)

That''s also why (and how) blue and yellow paint give green. Pigments absord certain colors (subtractive synthesis), unlike light which is additive. That''s why it seems backwards.

quote:
Oluseyi wrote:
If the amplitudes of the waves are equal in magnitude and opposite in sign at certain points, the waves cancel at those points. That''s how blue and green light produce yellow (the waves cancel each other partially, and what''s left is the yellow wavelength.)

This is wrong. Electromagnetic waves cancel each other out (or create interference) only if they are phaseshifted (or have another frequency, as you said) *and* are polarized on the same plane. This is true for eg. laser light. But it''s not true for ''normal'' light (sunlight, lightbulb, or the light your screen produces). Normal light *never* creates interference, only polarized light does.

The reason why the red/green/blue thing works is follows:
The color-sensitive part of the human retina is composed of 3 types of light-sensitive cells (plus intensity cells, but that''s not for color). Each type of cell is sensitive only for a certain range of the light spectrum, but they *overlap*. This is the key: Take monochromatic green light, and only *one* cell type will be activated, you''ll see pure green. Same for red and blue. But if you have yellow light, with a wavelength between green and yellow, then 2 types of cells will be activated *at the same time*, those for green and red. Your brain will create the color ''yellow'' from it.

A monitor just uses this property of the human eye: to produce yellow, it activates green and red light (that do *not* interfere !), both wavelengths reach the eye, and the ''green wave'' activates the green cell, the ''red wave'' activates the red cell. The brain is fooled and *thinks* it is yellow (because both cell types are active, see above), and ''displays'' yellow into your mind...

- AH