Author Topic: RGBW  (Read 2093 times)

Offline WTalbot

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RGBW
« on: December 09, 2014, 02:35:06 PM »
I have played around with smart strings from DLA (TheBanker) for a couple years but have gone back to static.  I prefer lots of classic white lights.  One of my disappointments was the inability to obtain a true or classic white light.  I am curious if there is, or if anyone is working on, support for RGBW......or if there is a way to obtain a perfect white light from RGB?  They all kind of look grayish in color to me.

Offline bajadahl

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Re: RGBW
« Reply #1 on: December 09, 2014, 03:10:18 PM »
Will - If you want to swing back by I can show you the shades of white that I have been getting with the Minleons that line my driveway.  I'm not sure anything beats that warm white of a C9 Incan...

Offline Steve Gase

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Re: RGBW
« Reply #2 on: December 09, 2014, 05:05:25 PM »
little candles will get the look you  desire...

:P

Move to RGB, Will!! :)
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Offline corey872

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Re: RGBW
« Reply #3 on: December 09, 2014, 07:47:38 PM »
Here are a few of my favorite 'whites' from my personal recipe book.  I guess they look pretty good to me.  Not sure what you mean by 'gray', or 'perfect' white (ie perfect incandescent light, perfect white with no hint of red/blue, etc) but then guess everyone sees color a little different, but

You need to program these numbers as R, G, B values (respectively) in your favorite sequence program: (they're for TM1804 bullet nodes, others may need some adjustment)

60, 31, 07 - Warm white, very close to miniature lights
60, 26, 04 - yellow-white, approximately candle flame
255, 208, 107 - Snow white - no hint reds or blues
255, 208, 116 - 'hint of blue' white



Corey
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Offline algerdes

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Re: RGBW
« Reply #4 on: December 09, 2014, 07:49:02 PM »
Corey,
Does that "warm white" scale to brighter levels?
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Offline zwiller

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Re: RGBW
« Reply #5 on: December 09, 2014, 08:09:33 PM »
IMO, rgb and incans are just 2 different beasts...  It's like mp3 vs vinyl, man.  I tried most everything.  I love incans and love rgb, but they don't play well together.  If you gotta have incans, run em on top or under rgb.  If I had time I would do this and run some in classy aftershow static type thing since I am all rgb...
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Offline corey872

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Re: RGBW
« Reply #6 on: December 10, 2014, 06:20:54 AM »
Corey,
Does that "warm white" scale to brighter levels?

I'm not sure.  I use that to be the best approximation of color/brightness for the miniature lights.   Scaling would get a bit tricky, because if you start adding 1 to each of the numbers, the ratio changes.  But if you attempt to keep the same ratio (and hope all three colors have a linear response) you only have a few steps before red is maxed out:

60   31   7
157   35   8
177   40   9
196   44   10
216   49   11
235   53   12
255   58   13

Basically, I just used the 'Colorfinder' from Rick Raively.  Get set up so I can tab through the color sliders, then just eyeball the nodes and decide if the color I'm after needs more R, G or B and keep in mind R+G = Yellow, B+G = Cyan and R+B = Magenta.

(EDIT: - guess I should clarify this a bit... the original 'warm white' 60, 31, 7 was found using the color slider.  The values above were calculated in a spreadsheet by just keeping the RGB ratios the same.)

In comparing to incandescents, one of the big factors I've noted (besides dimming curve) is the LEDs are almost overpoweringly bright.  For most the RGB colors, I have the value set around 125(or less) of 255, and the xLights brightness slider at 100 of 400, then sometimes sparkles or some other small effect at the full 255 to make a larger dynamic range.

Though in typing this just now, it occurs to me I could likely expand the dynamic range even more by setting the brightness to the full 400 and possibly dropping the main colors to maybe 40-60 in compensation, then the highlights should appear even brighter when they hit 255.
« Last Edit: December 10, 2014, 07:54:17 AM by corey872 »

Offline zwiller

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Re: RGBW
« Reply #7 on: December 10, 2014, 06:39:47 AM »
After reading Corey's post I felt compelled to post again.  RGB does NOT fade/ramp like incan, BUT I have found a trick that helps alot.  Not sure other sequencers can do it, but in LSP if you use a ramp down AND choose a color fading to black (or vice versa), it really mimics the dimming curve of incans and is real smooth and goes really low to off instead of what appears to be rgb just turning off at 25% output on just a plain ramp/fade.  This was a huge thing for me and for a while I thought it was a hardware limitation...

KUDOS to Corey and all who put this much effort in compensating for rgb and incans! 

Offline WTalbot

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Re: RGBW
« Reply #8 on: December 11, 2014, 11:33:29 AM »

I guess this means that there is really no demand for use of RGBW?

Offline corey872

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Re: RGBW
« Reply #9 on: December 11, 2014, 03:39:46 PM »
I would suspect demand would be pretty minimal.  There would be many issues... you'd have the cost/complexity of another LED die added to the group, you'd need a new 4-channel driver chip, which would cost more, likely a bit more board space and more components inside the node, and all the controllers would need to transmit 1/3 again as much data for that channel which would likely mean lower FPS, at least with the legacy stuff.

After all that, you'd be locked into the one 'white' the manufacturer chose for that LED die.  Does it happen to be a blue-white, a snow-white, a warm/yellow white, etc?  Plus, in dimming a white LED, it still won't match an incandescent because an incandescent tends to give a warmer color as it dims, while an LED remains relatively constant.  So seems like an RGBW would be a very small / niche market, if any at all, which would further lose any savings from 'economy of scale'.

Curious - did the color suggestions above not yield satisfactory results?   If something still seems off, let us know - there might be other ways to achieve the effect you're after.

I doubt an LED could ever 'perfectly' replace an incandescent bulb, though I suspect the best chance to mimic incandescent actually comes from better control of an RGB node - which would have the best chance to reproduce the wide range of color temperatures and brightness' emitted by an incandescent - vs adding a white LED to the mix which would be more static in color temp.

Offline jnealand

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Re: RGBW
« Reply #10 on: December 11, 2014, 03:50:02 PM »
I probably have a case of LED cool white lights from a single source and I have to go thru every box to find strings that match because even though the box says cool white.  Some are bright white, some have a blue tint, some kind of green tint, and a couple that just don't seem to match anything.  Frustrating.
Jim Nealand
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Offline algerdes

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Re: RGBW
« Reply #11 on: December 16, 2014, 10:45:52 AM »

... Scaling would get a bit tricky, because if you start adding 1 to each of the numbers, the ratio changes.  But if you attempt to keep the same ratio (and hope all three colors have a linear response) you only have a few steps before red is maxed out:

60   31   7
157   35   8
177   40   9
196   44   10
216   49   11
235   53   12
255   58   13

Basically, I just used the 'Colorfinder' from Rick Raively.  Get set up so I can tab through the color sliders, then just eyeball the nodes and decide if the color I'm after needs more R, G or B and keep in mind R+G = Yellow, B+G = Cyan and R+B = Magenta.

(EDIT: - guess I should clarify this a bit... the original 'warm white' 60, 31, 7 was found using the color slider.  The values above were calculated in a spreadsheet by just keeping the RGB ratios the same.)

In comparing to incandescents, one of the big factors I've noted (besides dimming curve) is the LEDs are almost overpoweringly bright.  For most the RGB colors, I have the value set around 125(or less) of 255, and the xLights brightness slider at 100 of 400, then sometimes sparkles or some other small effect at the full 255 to make a larger dynamic range.

Though in typing this just now, it occurs to me I could likely expand the dynamic range even more by setting the brightness to the full 400 and possibly dropping the main colors to maybe 40-60 in compensation, then the highlights should appear even brighter when they hit 255.

Good information, and  just about what I was thinking. 
Thanks

 

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