White colour in 2D window

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hmschreiber
Posts: 18
Joined: Wed Dec 02, 2015 6:49 am
Real Name: Herbert Schreiber

Hello,

I have RGBW Led´s. All is working. But in the 2D window I don´t get a White light. The DMX channel is correct shown in the dmx view, but not in the 2d window. It only works with RGB Led´s if all (RGB) are 100%.

Do I think wrong?

Thanks for the very nice new Feature in 4.10.2. The Option for the xy Panel to select fixtures is absolut great.

Herbert
janosvitok
Posts: 1274
Joined: Mon Apr 13, 2015 7:05 am
Location: Bratislava, Slovakia
Real Name: Jano Svitok
Contact:

RGBW/RGBA/RGBAW/etc. are not yet supported. It's not quite clear how we should display the value... i.e. how to map RGBW space to RGB and still maintain some needed properties, like
RGB and RGBW fixtures using only RGB channels should display the same color...
boxy
Posts: 306
Joined: Tue Apr 21, 2015 8:18 am
Real Name: Robert Box

I think I've found a fix (once and for all) for the RGBW-RGB screen conversion problem (I did it in Excel):

1. Take the 4 RGBW values (Ra, Ga, Ba, Wa).
2. Store the maximum of these values (RGBWmax).
3. Create intermediate RGB values by summing each colour and the white value (Rb, Gb, Bb). This can create values larger than 255.
4. Store the maximum of the intermediate values (RGBmax).
5. Calculate the final RGB values by dividing by the second maximum and multiplying by the first (Rx, Gx, Bx). This maintains the previous highest RGBW value.

Rx=(Ra+Wa)/RGBmax*RGBWmax
Gx=(Ga+Wa)/RGBmax*RGBWmax
Bx=(Ba+Wa)/RGBmax*RGBWmax

This does several things:

1. White light only gives a range of greys 0-#FF (good).
2. RGB greys are also maintained 0-#FF (good).
3. Adding white on top of RGB greys moves the numbers towards #FF (good).
4. Adding more white to RGB white makes no difference (bad).
5. Adding white to medium brightness colours makes them brighter and more washed out (good).
6. Adding white to a fully saturated color (eg. 255 red) brings up the values of the others (good), but does not increase the saturated colour further above #FF, obviously (bad).

To adapt this for amber and UV colours, the following function would be used:

Rx=(Ra+Wa+Aa x AweightR+UV x UVweightR)/RGBmax*RGBWAUVmax
Gx=(Ga+Wa+Aa x AweightG+UV x UVweightG)/RGBmax*RGBWAUVmax
Bx=(Ba+Wa+Aa x AweightB+UV x UVweightB)/RGBmax*RGBWAUVmax

Aweight is (1, 0.75, 0) and UVweight is (0, 0.58, 0.83) to reflect the lamp colour.

In the spreadsheet, column N shows how adding white changes the RGB base colour by 5 levels (0, 64, 128, 191, 255). This is what you would get in the 2D window as the white faders go up.

All that is left now is to implement the equtions without using floats in an efficient manner. Easy!

http://www.boxy.biz/RGBW_equation2.xlsx
http://www.boxy.biz/RGBA_equation2.xlsx
http://www.boxy.biz/RGBUV_equation2.xlsx
Jules
Posts: 5
Joined: Fri Mar 18, 2022 12:14 pm
Real Name: Jules

Hello there!
I am new to QLC+ and i have the same problem, i dont see how i could apply the named solution by boxy. Is there any fix to this? I am on QLC+ 4.12.4
Cheers
Jules
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