{
  stdenv,
  imagemagick,
  gawk,
  src,
}:
stdenv.mkDerivation {
  pname = "invert-image-avg";
  version = "1.0";

  inherit src;

  buildInputs = [
    imagemagick
    gawk
  ];

  # input is a file, not a directory, skip unpackPhase
  unpackPhase = "true";

  # command taken from: https://old.reddit.com/r/swaywm/comments/oz3t7v/setting_a_blurred_background_with_swaylock_and/
  buildPhase = ''
    rm -fr $out
    magick ${src} -channel RGB -negate -resize 1x1 txt: | awk 'FNR == 2 {print $3}' > $out
  '';
}