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.
       
 (HTM) toggle-monitor-grayscale project on Github
       
       # Conclusion
       
       I have no idea why someone would like to turn the screen in black and
       white, but I've been curious to see how it would look like and if it
       would be nicer for the eyes, it's an interesting experience I have to
       admit but I prefer to keep my colors.