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Topic: Led Matrix : white component purpose in RGBW led strips? (Read 223 times) previous topic - next topic

PaulBreugnot

Hi everybody!

This discussion is not directly linked to Arduino, however is is linked with a lot of projects using Arduino.

I'm currently working on a led matrix projects with other people.
We have already a working prototype and I am developing a Java application to pilot the leds, that are in a RGBW led strip.
We initially started to develop our own software because existing programs such as Glediator or FastLed doesn't handle led strips with a white component, what becomes more and more common.

Finally, we have those RGBW led strips, we have an app to control the four components, but we don't know what to do with the last one, and it has to be there for something, and we would like to optimize this something!

So here is an open discussion : What is exactly the purpose of the white component?
Are they only here to provide a more simple way to display pure white, instead of doing R+G+B (that gives, it is true, a less pure white)?
Could they have a more general utility, in terms of other colors? Because finally, in an animation, pure white is quite unusual.

In Java, I'm using the Javafx 8 Color class that provides a simple way to switch from HSV color representation (that I am using to generate animations) to RGB representation (the only thing that leds understand).
Visually speaking, it seems that adding white is like increasing the "Value" component, or brightness. But this is easier and works perfectly with the RGB system, without the white led.
Could the fact that changing only one component (the white component) instead of the 3 others to generate the same color could be used to create a faster communication protocol between the program that generate the animations (that run on a computer, server or other) and the microcontrollers (currently Arduino like cards using the Adafruit NeoPixel library) which transmit data to the leds? (currently, the program transmit all the 4*[number_of_leds] components at each frame to the microcontroller through USB or WiFi)
Could there be interests in terms of energy consumption?

Any idea is welcome!

Paul

BONUS : in attachment, a photo of our led panel and screenshots of the app. ;-)

Grumpy_Mike

#1
Jun 13, 2018, 08:08 am Last Edit: Jun 13, 2018, 08:11 am by Grumpy_Mike
Quote
Could they have a more general utility, in terms of other colors? Because finally, in an animation, pure white is quite unusual.
No not really, I twice saw a half hour set of contemporary music, different artists, accompanied by a light show that consisted entirely of white anamatin. And when I was In Vagus the fountains of the Balagero hotel was illuminated entirely in white.

It is used to make better whites, brighter whites, whites with colour tints and less saturated but brighter colours.

Quote
Could the fact that changing only one component ............
No


Nothing much to discuss if you ask me.

PaulBreugnot

I finally found those very interesting documents :
 - http://blog.saikoled.com/post/44677718712/how-to-convert-from-hsi-to-rgb-white
 - http://www.mirlab.org/conference_papers/International_Conference/ICASSP%202014/papers/p1214-lee.pdf
 - http://web.archive.org/web/20101008153429/http://www.nouvoyance.com:80/files/pdf/Adding-a-White.pdf
They show several algorithms that can be used to convert a RGB/HSV represented color to a RGBW color, improving some brightness properties of saturated colors, reducing power consumption and making some colors more natural, especially pastel colors.

I think that was what I was looking for! Thank you for your answers!

xl97

color/saturation aside...

why use 3 x leds @ (roughly) 20mA each = 60mA... to get white..  when you can now just use the dedicated 'white' led @ 20mA?


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