Start a new topic

Color codes

 Patrick,


could you explain how R, G, B values map into the color codes the Nextion is using?


Since WHITE is 65535, it looks like the Nextion has 16 bits to specify colors, so we theoretically have 5 bits each for red, green and blue - but how are they distributed and what does the 16th bit?


it just use a 565 schema ...

5 bits R
6 bits G
5 bits B

rrrrrggggggrrrrr

convert a full 24Bit RGB into 16Bit 565

565value=int(R/8)*2048+int(G/4)*32+int(B/8)


Gerry


I know you asked Patrick But may this will help 

Read the thread most answers are there 

http://support.iteadstudio.com/support/discussions/topics/1000064883


"The colors are in 16-bit 565 format.   Hue Sat Lum is calculated when RGB is entered.

For sake of correctness, H/S/L input could also calculate RGB, but most people never think in H/S/L.


24 bit RGB in binary is RRRRRRRR GGGGGGGG BBBBBBBB or in Hexadecimal as FF FF FF

565 uses 5 upper bits of red, 6 from green, and 5 from blue: RRRRRRRR GGGGGGGG BBBBBBBB

Therefore your color 33973: red is 128 green is 148 and blue is 21.  in RGB Hexadecimal 8094A8.


33973 / 2048 = 16.  16 * 8 = 128   Red

(33973 % 2048) / 32 = 37.  37 * 4 = 148   Green

 

(33973 % 32) = 21.  21 * 8 = 168  Blue


"




Thank you all!

 

How do I convert HSL to 16bit 565 format.

Internet would have algorithms for HSL to 565 format.

Certainly fewer people would think in terms of HSL

It does, but I'm not smart enough to write those algorithms on nextion hmi local code. Is what I'm hoping todo even possible? I believe more people would think in terms of Hsl than rgb. Anywhere you select a color in software you are given a hsl mapped image. When trying to create lighting animation algorithms I don't know how I could think about a gradient change in rgb.

effects like fading or gradients are nothing magic, even not in RGB and 565 ...


but indeed you need some knowledge to code it ...


your hobby, your choice, your duty ...

tft
(141 KB)

Nextion is an HMI device.  Human Machine Interfacing.


Although HSL to 565 conversion for entered values can probably be achieved if someone invests their time to accomplish, realizing a color chooser is perhaps more challenging.  Nextion was not designed for this purpose, and it does not have an NVidia graphics card to assist.  Touch coordinates of a touch for selection will need to be looped to an MCU over serial and sent back to Nextion.  Touch on Resistive or even the Capacitive display may have higher resolution on the inner, but will lose coordinate resolution accuracy the closer to the edge you go.  


So perhaps interesting as a Proof of Concept, but less efficient use of cycles to perform such calculations and other than font color will have no value.  The final resolution of 16 bit color 0 to 65535 will become your most limiting factor  - HSL tends to be for 24 bit, 32 bit and higher - such resolution is indeed lost on 16 bit.

Login or Signup to post a comment