Color Gamma and Brightness Issue

EL Wire/Tape/Panels, LEDs, pixels and strips, LCDs and TFTs, etc products from Adafruit

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
imrana1
 
Posts: 35
Joined: Sun Apr 28, 2013 5:35 pm

Color Gamma and Brightness Issue

Post by imrana1 »

Hey,

So I was wondering why If I output a RGB value that shows a specific color on the computer screen on the neopixelmatrix, I am not able to get the same color. I feel that the neopixel can express a variety of colors (the library provides 16 bit resolution?) but when I input a color that outputs 'sky blue' I get a color rounded off to cyan. It may have to do with power since I am using 3 batteries which supply 4.5V , will I be able to use 4 batteries and a diode connected in series to drop the voltage from 6V to 5V? Is this power issue the reason why red,blue and green are the only colors that glow the brightest?

My other question is how does the Adafruit Library scale the colors of the neopixel to show the same color with a lower brightness, because I would like to make a singular Neopixel fade while others stay on, there is the setbrightness function which changes the brightness of the whole matrix but I would like to control the brightness of each neopixel.


In summary I just want the ability to show the difference between #7cdee7 and #41cfdc an analogy would be that the neopixel simply rounds the color off however I need to have that resolution. Thoughts?

Thanks

User avatar
adafruit_support_mike
 
Posts: 67446
Joined: Thu Feb 11, 2010 2:51 pm

Re: Color Gamma and Brightness Issue

Post by adafruit_support_mike »

You're dealing with a difference between additive and subtractive color spaces.

A computer monitor uses liquid crystals that block parts of the spectrum generated by a white backlight. NeoPixels generate light, which among other things means there's no combination of color values that will make them turn black.

If you want a one-to-one mapping between the two color spaces, you'll have to mount the NeoPixels in some kind of housing with a display that starts off being black and becomes brighter as you add color.

The technical way to do that is with a black-body chamber: a box whose inside surface is entirely matte black, and which has a hole cut in one side. When you look at the hole, you see an approximation of a truly black surface. Mount each pixel inside such a box, positioned so any light it emits will reflect off the inner walls before passing out through the hole. The dimensions of the box will determine the amount of light that makes it out the hole for any LED output level, thus setting the luminance level of 0xffffff-white.

User avatar
imrana1
 
Posts: 35
Joined: Sun Apr 28, 2013 5:35 pm

Re: Color Gamma and Brightness Issue

Post by imrana1 »

Hi!

Thank you for the important insight however I was wondering how would I make specific neopixels fade, an example would be to have a row of 5 neopixels and the 1st, 3rd and 5th fade in and out in brightness while the other 2nd and 4th neopixel stays as a solid color.

Thanks in advance!

Locked
Please be positive and constructive with your questions and comments.

Return to “Glowy things (LCD, LED, TFT, EL) purchased at Adafruit”