Redscreen is a simple script that uses the xcalib monitor calibration tool to put a red color filter on your X server display.
Download the script, put it somewhere in your execution path, and chmod +x it. Run the script without arguments to go into redscreen mode. Give it the 'off' argument to return back to normal.
Running the script with 'dim' will restore the color but leave the brightness low- useful if you need to duck out of full red mode to check something without completely blinding yourself. Running it with 'inv' will invert the palette.
The xcalib program is kind of wierd in that it doesn't allow setting levels to an absolute value. The only way I could find to set the monitor to a consistent value with it is to clear the settings to the default before doing the modification. As such (user beware!) there is a little bit of a flash when running the script. I suggest you blink while changing between red and dim modes.
#!/bin/csh # redscreen.csh Tue Jun 24 16:59:21 PDT 2014 Jeff Jahr # Usage if ($1 == "-h") then echo "$0 [-h | dim | inv | off]" exit endif # Return to normal settings if ( $1 == "off" ) then xcalib -clear exit endif if ($1 == "inv" ) then xcalib -i -a exit endif # Make the screen darker if ($1 == "dim" ) then xcalib -clear xcalib -co 30 -alter exit endif # Turn the screen red # xcalib
xcalib -clear #xcalib -co 60 -alter xcalib -green .1 0 1 -alter xcalib -blue .1 0 1 -alter xcalib -red 0.5 1 40 -alter