RGB and Color Count

[pschlosser]

Some of the simpler RGB setups I’ve seen claim they are 7 colors. That makes sense, if any one of the three (R, G, B) lasers are on or off. Since they can only be on, or off, in these simple setups, that is two states by three lasers. Thus, the number of combinations is 2 ^ 3 (raised to the power of 3,) which equals eight. But no one counts it a color when all three lasers are off (black,) so we subtract one for black, resulting in 7 colors.

When you mix a red and a green laser, let’s say 650nm and 532nm, it makes a yellow color. But don’t we refer to that color as 532/650nm yellow? It surely isn’t a 594.1 nm (produced from a HeNe gas laser) yellow. We aren’t going to get any other shades of yellow, are we? (although the mean of 650nm and 532nm is 591nm... hmm, very suspicious 591nm is yellow)

Can we get way more colors, if we attenuate the Red, Green, or Blue? I mean, if we could operate each laser in 25% increments, such as 0%, 25%, 50%, 75%, and 100% output power. Are we going to get any new colors? If so, we could be talking about 5 ^ 3 (less black) which is 124 colors.

My brain is hurting trying to get my head around this. I counted the colors in the images shown in Flaminpyro’s signature, and I think I count seven colors. Presuming that is one of JayRob’s elegant White Fusion RGB builds, I am concluding the lasers are just TTL controlled, on or off.

There must be something I am overlooking. Because how can a 445nm diode being used in a DLP projector (presumably with accompanying red and green) produce enough colors to properly display an image? (I concede I am at a disadvantage having never gutted a DLP)

I may have an RGB ReKe coming, soon, and my thoughts have turned to areas I’ve not completely worked out in my head, or fully understand. Dang, I have a ton more reading to do. I invite any thoughts or links to reading material.

 

[ZRaffleticket]

That's why they're "...simpler RGB setups..."
You can set it up like a computer monitor or television and set them in groups of 0-255, that would result in about 16.8 million color combinations. The reason you don't see that often is because it's not easy to incorporate them together like this, because it's easier setting it up as "on" or "off".

 

[hakzaw1]

ttl in rg&b 7 bolors
analog modulation >thousands of colors
cheap rgb or rgbr PJs that claim 'full color' are 'full' of 5hit.
ttl only can make r,g,b, magenta, teal and yellow plus whiteish= 7.
ttl blanking means on or off no in-betweens
black lasers are the safest- require no eyeware or batteries but as they are made mostly from unobtainium they are quite rare.

Your new REKE is 7 color.

PJs under ~$800 are very rarely analog modulation=

 

[Cyparagon]

(although the mean of 650nm and 532nm is 591nm... hmm, very suspicious 591nm is yellow)

The mean doesn't matter in the least. You can simulate any color between the two by varying the power of the constituents. If anything, equal parts of red and green will still look green - not yellow - since green is substantially brighter.

Many DACs operate at 8 bits per color channel, giving 2^8^3 = 16.7 million theoretical colors.

 

[chipdouglas]

If you want lots of colors, you need analog modulation. You'll need software and a dac to control it properly so you can get full function.

Some of the simpler RGB setups I’ve seen claim they are 7 colors. That makes sense, if any one of the three (R, G, B) lasers are on or off. Since they can only be on, or off, in these simple setups, that is two states by three lasers. Thus, the number of combinations is 2 ^ 3 (raised to the power of 3,) which equals eight. But no one counts it a color when all three lasers are off (black,) so we subtract one for black, resulting in 7 colors.

When you mix a red and a green laser, let’s say 650nm and 532nm, it makes a yellow color. But don’t we refer to that color as 532/650nm yellow? It surely isn’t a 594.1 nm (produced from a HeNe gas laser) yellow. We aren’t going to get any other shades of yellow, are we? (although the mean of 650nm and 532nm is 591nm... hmm, very suspicious 591nm is yellow)

Can we get way more colors, if we attenuate the Red, Green, or Blue? I mean, if we could operate each laser in 25% increments, such as 0%, 25%, 50%, 75%, and 100% output power. Are we going to get any new colors? If so, we could be talking about 5 ^ 3 (less black) which is 124 colors.

My brain is hurting trying to get my head around this. I counted the colors in the images shown in Flaminpyro’s signature, and I think I count seven colors. Presuming that is one of JayRob’s elegant White Fusion RGB builds, I am concluding the lasers are just TTL controlled, on or off.

There must be something I am overlooking. Because how can a 445nm diode being used in a DLP projector (presumably with accompanying red and green) produce enough colors to properly display an image? (I concede I am at a disadvantage having never gutted a DLP)

I may have an RGB ReKe coming, soon, and my thoughts have turned to areas I’ve not completely worked out in my head, or fully understand. Dang, I have a ton more reading to do. I invite any thoughts or links to reading material.

 

[pschlosser]

Wow, thanks people. Good data. I appreciate the info.

So our intuition was right. When we can vary the intensity of the RGB colors, we get more possible outcomes, just like an RGB monitor. That makes a great deal of sense.

@Hakzaw, I was concluding the RGB ReKe was 7 color. I could find no evidence to the contrary.

 

[Bionic-Badger]

If you want to learn more about how colors can be created, look up the CIE color system.

It'd probably be better to say that the Reke is 7-colors at a time. You can mess with the pots to change the color somewhat, but not on the fly.

 

[hakzaw1]

Wow, thanks people. Good data. I appreciate the info.

So our intuition was right. When we can vary the intensity of the RGB colors, we get more possible outcomes, just like an RGB monitor. That makes a great deal of sense.

@Hakzaw, I was concluding the RGB ReKe was 7 color. I could find no evidence to the contrary.

^^^ Discriptions of Chi-jectors will often say 'Full color' even in ones with just two lasers- Or in a RG they may say in the 'specs'(in this case the term is used very loosely) something like 100mW of red 650 & 50mW of Green and 150mW of yellow- when in the 'real' world the truth is 60mW of R and 30 mW of G and the yellow ( before losses) is a 'combined' 90mW.

In all fairness the dropshipers only cpoypasta what the REAL makers tell them. Do you really think they all make ther own lasers and actually have a LPM??


They are not neccessarily being dishonest but rather just not understanding why theirs is NOT full color- Of course if they tried that on Ebay then every buyer would be able to truthfully say the item was not as discribed and ask for a refund... thus they donot even try to sell on Ebay.

..AND as long as sales are brisk and complaints are few, there is no incentive to be accurate at all. :wave: