xcalib commands follow this structure
xcalib -color <gamma> <brightness-percent> <contrast-percent>
I then issue two commands as one to try and adjust the amount of red on my screen. This does make the screen 'red'er.
xcalib -green 0.1 0 1 -alter && xcalib -blue 0.1 0 1 -alter
Why then don't the three sets of commands shown below produce different results? Notice I vary the gamma argument each time, eg
50. Yet my screen is heavy red under each command.
xcalib -green 0.1 0 1 -alter && xcalib -blue 0.1 0 1 -alter xcalib -green 0.9 0 1 -alter && xcalib -blue 0.9 0 1 -alter xcalib -green 50 0 1 -alter && xcalib -blue 50 0 1 -alter
What would be some xcalib commands to vary the amount of red, rather than have a hard on/off, which my commands above yield.
Note - I am aware that I could use GNOME night light, which is buggy on my installation. Or I could use redlight, which also has issues. But I prefer xcalib for it's simplicity, and I like manually setting things vs flux, redlight, etc changing settings as the sun rises and sets.