| Title: Turn your Xorg in black and white
Author: Solène
Date: 15 May 2021
Tags: unix
Description:
# Introduction
If for some reasons you want to turn you display in black and white
mode and you can't control this on your display (typically a laptop
display won't allow you to change this), there are solutions.
# Compositor way
The best way I found is to use a compositor, fortunately I'm already
using "picom" as a compositor along with fvwm2 because I found the
windows are getting drawn faster when I switch between desktop with the
compositor on. You will want to run the compositor in your ~/.xsession
file before running your window manager.
The idea is to run picom with a shader that will turn the color into a
gray scale, restart picom with no parameter if you want to get colors
back.
```command line sample
picom -b --backend glx --glx-fshader-win "uniform sampler2D tex; uniform float opacity; void main() { vec4 c = texture2D(tex, gl_TexCoord[0].xy); float y = dot(c.rgb, vec3(0.2126, 0.7152, 0.0722)); gl_FragColor = opacity*vec4(y, y, y, c.a); }"
```
It was surprisingly complicated to find how to do that. I stumbled on
"toggle-monitor-grayscale" project on github which is a long script to
automate this depending on your graphic card, I only took the part I
needed for picom.
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