convert fog.jpg -resize 800x600\> -ordered-dither h4x4a -transparent white transparentfog.gif
      

      convert fog.jpg -resize 800x600\> -ordered-dither h4x4a -transparent black transparentblackfog.gif
      

  convert gits.jpg -resize 800x900\> -ordered-dither 3x3 -colorspace gray -threshold 90% gits.png
  

  convert gits.jpg -resize 800x900\> -ordered-dither 2x2 -colorspace gray -threshold 90% gits2.png
  

  #!/bin/sh
for f in *.jpg and *.png
do 
    infile=$f
    name=$(echo "$infile" | cut -f 1 -d '.')
    palette=$name'_palette'.png
    outfile=$name'_out'.png
    smallerimage=$name'_smaller'.png
    
    if [ ! -f $outfile ]; then
        # scale image down 
        convert $infile -resize 800x600\> $smallerimage
        # generate palette 
        ffmpeg -i $infile -vf palettegen=max_colors=4 $palette

        # generate dithered png with palette
        ffmpeg -i $smallerimage -i $palette -lavfi "paletteuse=bayer:bayer_scale=1" $outfile
        
        # remove palette to save space
        rm $palette $smallerimage
    else
        echo '$outfile already done, moving on'
    fi
done 


  

same script as for rail pic above

convert egg.jpg -resize 800x600\> -ordered-dither 4x4 -colorspace gray -threshold 50% egg.png