dither.sh

#!/bin/zsh

for palette in $(ls palettes/)
do
  echo $palette
  for file in $(ls |grep -v palette |grep -v .sh)
  do
  echo $file
  convert $file \
    -resize 400x \
    +dither /tmp/resized.png

  convert /tmp/resized.png \
    -define dither:diffusion-amount=12% \
    -dither FloydSteinberg \
    -remap palettes/$palette /tmp/remapped.png

  convert /tmp/remapped.png \
    -scale 1920x \
    -quality 100 \
    ${file%.*}-${palette%.*}.png
  done
done