How does a TV make white
How does a TV make white
(OP)
Hi All,
What is the equation a tv uses to make white? I ask because 100% of red green and blue doesn't make white. I read that 59 percent green and 30 percent red and 11 percent blue makes white.
Does anyone have a more detailed link about this?
What is the equation a tv uses to make white? I ask because 100% of red green and blue doesn't make white. I read that 59 percent green and 30 percent red and 11 percent blue makes white.
Does anyone have a more detailed link about this?





RE: How does a TV make white
Perhaps you are thinking about the lighting power of the phosphors on the CRT?
RE: How does a TV make white
RE: How does a TV make white
Note that not all monitors necessarily have the identical color filters for R, G, and B, so there is some degree of tweaking along the way to ensure that the perceived output appears "white"
TTFN
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RE: How does a TV make white
RE: How does a TV make white
There are color instruments that put out the color they see as values. Perhaps you can get one of these and then use automation to find white and any other colors you're after.
Have the instrument put out to a file along with the value you are running from your controller. Have your controller put out every possible setting then look at the instruments output file to find white and the corresponding values that were being put out by your controller.
Keith Cress
kcress - http://www.flaminsystems.com
RE: How does a TV make white
RE: How does a TV make white
x*R + y*G + z*B
the coefficients are tweaked until you get white.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: How does a TV make white
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If we learn from our mistakes I'm getting a great education!
RE: How does a TV make white
How much of each colour depends on the wavelengths of the original red, green and blue sources.
For instance what optical wavelength is really green ?
If you had a variable frequency light source, and ask ten different people to adjust it to "perfect" green, you will have ten slightly different wavelengths, and a big argument.
Likewise red and blue. You can drift towards or away from the infrared, and it will still be red, or towards or away from ultraviolet, and it will still be blue.
TV camera sensitivities and CRT phosphors vary a lot in peak sensitivity and peak output.
There have been different standards proposed over the years in various countries but the whole thing has become a historic mess.
One of the original standards for colour TV was the CCIT chromaticity standard. I suggest you Google this to get a deeper understanding.
Black is pretty easy, but the number of different types of white paint available from a paint store, and they ARE different might convince you that true white is not so easily defined.
Back in my student days I leaned that the sensitivity of the human eye to various colours is:
Red 30%
Green 59%
Blue 11%
The eye being most sensitive to green, and least sensitive to blue.
In the end, you will have to decide for yourself if what you are looking at is really white light.
Hold a sheet of white paper against the background of this post and see what two very different whites look like.
RE: How does a TV make white
Here:
http://www.handprint.com/HP/WCL/color1.html
http://www.handprint.com/HP/WCL/color2.html
(* just kidding)
RE: How does a TV make white
Your constants are used for calculating the luminance of the signal based upon the component colors. This is what allows B/W TVs to work with a color broadcast signal. It has zero to do with how white is made.
LEDs cover a fairly narrow band of wavelengths. They need to be in a proper proportion to each other to create the perception of white, and the chosen wavelengths will have a lot to do with that. Once the proper wavelength bins are chosen, you will need to adjust each bin's intensity... as suggested above, you cannot simply run the LEDs all at full power and expect white (for multiple reasons, which I won't get into here).
I have to ask... what is this for? I've looked at a number of your questions (many pertaining to LEDs) and I begin to question if this is a manufacturable product or a hobby one-off type deal...
Dan - Owner

http://www.Hi-TecDesigns.com
RE: How does a TV make white
You should check on avsforum.com, those guys love this sort of thing.
RE: How does a TV make white
You need to check the led data sheets to find out
how much light and at what wavelength the led gives off
at a set current.
National semi, cypress and philips have alot
on leds and color mixing.
Try:
Bob Pease, Analog by design show
Driving high power leds without getting burned. Parts 1&2
http://www.national.com/nationaltv/
and
ht
RE: How does a TV make white
Dan - Owner

http://www.Hi-TecDesigns.com