identify -verbose  image.png
  convert  image.png miff:- | identify -verbose -
  convert  image.png  -verbose -identify null:
  convert  image.png  -verbose info: 

#!/usr/bin/bash

  convert  tree.gif  -format %c  -depth 8  histogram:info:- 

        16: (  0,128,  0) #008000 green
       422: (  0,255,255) #00FFFF cyan
       126: ( 46,139, 87) #2E8B57 SeaGreen
       381: ( 50,205, 50) #32CD32 LimeGreen
        59: (160, 82, 45) #A0522D sienna
        20: (255,255,  0) #FFFF00 yellow 

#!/usr/bin/bash

  magick convert  tree.gif  -format %c  -depth 8  histogram:info:- 

    16: (0,128,0) #008000 green
    422: (0,255,255) #00FFFF cyan
    126: (46,139,87) #2E8B57 SeaGreen
    381: (50,205,50) #32CD32 LimeGreen
    59: (160,82,45) #A0522D sienna
    20: (255,255,0) #FFFF00 yellow 

  convert  tree.gif histogram:- | identify -depth 8 -format %c - 

#!/usr/bin/bash

  convert tree.gif -unique-colors -scale 1000%  tree_colors.gif
  convert tree.gif -unique-colors -depth 16  txt:- 

# ImageMagick pixel enumeration: 6,1,65535,srgb
0,0: (41120,21074,11565)  #A0A052522D2D  sienna
1,0: (0,32896,0)  #000080800000  green
2,0: (12850,52685,12850)  #3232CDCD3232  LimeGreen
3,0: (11822,35723,22359)  #2E2E8B8B5757  SeaGreen
4,0: (65535,65535,0)  #FFFFFFFF0000  yellow
5,0: (0,65535,65535)  #0000FFFFFFFF  cyan 

#!/usr/bin/bash

  magick convert tree.gif -unique-colors -scale 1000%  tree_colors.gif
  magick convert tree.gif -unique-colors -depth 16  txt:- 

# ImageMagick pixel enumeration: 6,1,65535,srgb
0,0: (41120,21074,11565)  #A0A052522D2D  sienna
1,0: (0,32896,0)  #000080800000  green
2,0: (12850,52685,12850)  #3232CDCD3232  LimeGreen
3,0: (11822,35723,22359)  #2E2E8B8B5757  SeaGreen
4,0: (65535,65535,0)  #FFFFFFFF0000  yellow
5,0: (0,65535,65535)  #0000FFFFFFFF  cyan 

#!/usr/bin/bash

  convert rose: -colors 256 -format %c histogram:info:- |
    sed 's/:.*#/ #/' |
    while read count color colorname; do
       convert -size 1x$count xc:$color miff:-
    done |
       convert - -alpha set -gravity south -background none +append \
                  unique_color_histogram.png 

    Powershell 1.4.5 で、移植完了 

#!/usr/bin/bash

  convert rose: -scale 1x1\! -format '%[pixel:s]' info:- 

srgb(146,89,80) 

#!/usr/bin/bash

  magick convert rose: -scale 1x1`! -format '%[pixel:s]' info:- 

srgb(57.142%,35.0042%,31.5557%) 

#!/usr/bin/bash

  convert rose: -scale 1x1\! \
    -format '%[fx:int(255*r+.5)],%[fx:int(255*g+.5)],%[fx:int(255*b+.5)]' info:- 

146,89,80 

#!/usr/bin/bash

  magick convert rose: -scale 1x1`! `
    -format '%[fx:int(255*r+.5)],%[fx:int(255*g+.5)],%[fx:int(255*b+.5)]' info:- 

146,89,80 

#!/usr/bin/bash

  convert rose: -channel R -separate -format '%[mean]' info: 

37448 

#!/usr/bin/bash

  magick convert rose: -channel R -separate -format '%[mean]' info: 

37448 

#!/usr/bin/bash

  convert rose: -format '%[pixel:p{40,30}]' info:- 

srgb(232,54,58) 

#!/usr/bin/bash

  magick convert rose: -format '%[pixel:p{40,30}]' info:- 

srgb(232,54,58) 

#!/usr/bin/bash

  convert rose: -crop 1x1+40+30 -depth 8 txt:- 

# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (59624,13878,14906)  #E8363A  srgb(232,54,58) 

#!/usr/bin/bash

  magick convert rose: -crop 1x1+40+30 -depth 8 txt:- 

# ImageMagick pixel enumeration: 1,1,255,srgb
0,0: (232,54,58)  #E8363A  srgb(232,54,58) 

#!/usr/bin/bash

  convert tree.gif -fill black +opaque yellow \
                   -fill white -opaque yellow \
                   -print "yellow sun pixels = %[fx:w*h*mean]\n"   null: 

yellow sun pixels = 20 

#!/usr/bin/bash

  magick convert tree.gif -fill black +opaque yellow `
                   -fill white -opaque yellow `
                   -print "yellow sun pixels = %[fx:w*h*mean]\n"   null: 

yellow sun pixels = 20 

#!/usr/bin/bash

  compare -metric RMSE xc:Navy xc:blue null: 

18844.1 (0.287543) 

#!/usr/bin/bash

  magick compare -metric RMSE xc:Navy xc:blue null: 

18844.1 (0.287543) 

#!/usr/bin/bash

  compare -metric RMSE xc:'#0000' xc:'#FFF0' null: 

0 (0) 

#!/usr/bin/bash

  magick compare -metric RMSE xc:'#0000' xc:'#FFF0' null: 

0 (0) 

#!/usr/bin/bash

  compare -metric RMSE xc:'#000000' xc:'#FFFF00' null: 

53509.1 (0.816497) 

#!/usr/bin/bash

  magick compare -metric RMSE xc:'#000000' xc:'#FFFF00' null: 

53509.1 (0.816497) 

#!/usr/bin/bash

  compare -fuzz 20% -metric AE xc:Navy xc:Blue null:
  compare -fuzz 30% -metric AE xc:Navy xc:Blue null: 

1
0 

#!/usr/bin/bash

  magick compare -fuzz 20% -metric AE xc:Navy xc:Blue null:
  magick compare -fuzz 30% -metric AE xc:Navy xc:Blue null: 

1
1 

#!/usr/bin/bash

  compare -metric FUZZ xc:Navy xc:Blue null: 

18844.1 (0.287543) 

#!/usr/bin/bash

  magick compare -metric FUZZ xc:Navy xc:Blue null: 

18844.1 (0.287543) 

#!/usr/bin/bash

  compare -metric FUZZ xc:'#0000' xc:'#FFF0' null: 

0 (0) 

#!/usr/bin/bash

  magick compare -metric FUZZ xc:'#0000' xc:'#FFF0' null: 

0 (0) 

#!/usr/bin/bash

  convert xc:Navy  -fuzz 20% -fill Blue -opaque Blue txt: 

# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,0,32896)  #000000008080  navy 

#!/usr/bin/bash

  magick convert xc:Navy  -fuzz 20% -fill Blue -opaque Blue txt: 

# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,0,32896)  #000000008080  navy 

#!/usr/bin/bash

  convert xc:Navy  -fuzz 30% -fill Blue -opaque Blue txt: 

# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,0,65535)  #00000000FFFF  blue 

#!/usr/bin/bash

  magick convert xc:Navy  -fuzz 30% -fill Blue -opaque Blue txt: 

# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,0,65535)  #00000000FFFF  blue 

#!/usr/bin/bash

  fuzz=%1
  color1="red"
  color2="#e00"

  color2=`convert xc:"$color2" -format '%[pixel:s]' info:`
  result=`convert  xc:"$color1" -alpha set -channel RGBA -fuzz $fuzz \
        -fill $color2 -opaque $color2 -format '%[pixel:s]' info:`
  if [ "$result" = "$color2" ]; then
    echo "Colors match according to Fuzz Factor"
  else
    echo "Colors DO NOT match"
  fi 

#!/usr/bin/bash

  convert colorwheel.png  -dither None       -colors 64  colors_64_no.gif
  convert colorwheel.png  -dither Riemersma  -colors 64  colors_64_rm.gif
  convert colorwheel.png  -dither FloydSteinberg \
                                             -colors 64  colors_64_fs.gif 

#!/usr/bin/bash

  magick convert colorwheel.png  -dither None       -colors 64  colors_64_no.gif
  magick convert colorwheel.png  -dither Riemersma  -colors 64  colors_64_rm.gif
  magick convert colorwheel.png  -dither FloydSteinberg `
                                             -colors 64  colors_64_fs.gif 

#!/usr/bin/bash

  convert logo: -resize 40% -crop 100x100+105+50\! -normalize  logo.png
  convert logo.png  +dither             -colors 8  colors_8_no.gif
  convert logo.png  -dither Riemersma   -colors 8  colors_8_rm.gif
  convert logo.png  -dither FloydSteinberg \
                                   -colors 8  colors_8_fs.gif 

#!/usr/bin/bash

  magick convert logo: -resize 40% -crop 100x100+105+50`! -normalize  logo.png
  magick convert logo.png  +dither             -colors 8  colors_8_no.gif
  magick convert logo.png  -dither Riemersma   -colors 8  colors_8_rm.gif
  magick convert logo.png  -dither FloydSteinberg `
                                   -colors 8  colors_8_fs.gif 

#!/usr/bin/bash

  convert rose:  +dither             -colors 16 colors_16_no.gif
  convert rose:  -dither Riemersma   -colors 16 colors_16_rm.gif
  convert rose:  -dither FloydSteinberg \
                                     -colors 16 colors_16_fs.gif 

#!/usr/bin/bash

  magick convert rose:  +dither             -colors 16 colors_16_no.gif
  magick convert rose:  -dither Riemersma   -colors 16 colors_16_rm.gif
  magick convert rose:  -dither FloydSteinberg `
                                     -colors 16 colors_16_fs.gif 

#!/usr/bin/bash

  convert -size 4x1 xc:blue -draw 'fill red   point 0,0' \
                                        -scale 20 colors_rb.gif
  convert -size 4x1 xc:red   -draw 'fill blue point 3,0' \
                                        -scale 20 colors_br.gif
  convert colors_rb.gif  -colors 1  colors_rb2.gif
  convert colors_br.gif  -colors 1  colors_br2.gif 

#!/usr/bin/bash

  magick convert -size 4x1 xc:blue -draw 'fill red   point 0,0' `
                                        -scale 20 colors_rb.gif
  magick convert -size 4x1 xc:red   -draw 'fill blue point 3,0' `
                                        -scale 20 colors_br.gif
  magick convert colors_rb.gif  -colors 1  colors_rb2.gif
  magick convert colors_br.gif  -colors 1  colors_br2.gif 

#!/usr/bin/bash

  convert -size 20x640  gradient: -rotate 90  gradient.png
  convert gradient.png   +dither  -colors 5   colors_gradient.gif 

#!/usr/bin/bash

  magick convert -size 20x640  gradient: -rotate 90  gradient.png
  magick convert gradient.png   +dither  -colors 5   colors_gradient.gif 

#!/usr/bin/bash

  for S in    RGB CMY sRGB GRAY \
              XYZ LAB LUV  \
              HSL HSB HWB  \
              YIQ YUV OHTA ; do \
    convert colorwheel.png   -quantize $S   +dither -colors 16 \
              -fill black -gravity SouthWest -annotate +2+2 $S \
              colors_space_$S.gif; \
    done 

#!/usr/bin/bash

  $dt = "RGB CMY sRGB GRAY XYZ LAB LUV  HSL HSB HWB  YIQ YUV OHTA".Split(" ")
  for ( $i = 0 ; $i -lt $dt.length ; $i++ ) {
    $S = $dt[$i]
    magick convert colorwheel.png   -quantize $S   +dither -colors 16 `
              -fill black -gravity SouthWest -annotate +2+2 $S `
              colors_space_$S.gif
  } 

#!/usr/bin/bash

  convert xc:red xc:yellow xc:green1 xc:cyan xc:blue \
          +append -filter Cubic -resize 100x100\!  -size 100x100 \
          gradient: +matte -compose CopyOpacity -composite alpha_gradient.png
  convert alpha_gradient.png  +dither  -colors 256  alpha_colors_256.png
  convert alpha_gradient.png  +dither  -colors 64   alpha_colors_64.png
  convert alpha_gradient.png  +dither  -colors 15   alpha_colors_15.png 

#!/usr/bin/bash

  magick convert xc:red xc:yellow xc:green1 xc:cyan xc:blue `
          +append -filter Cubic -resize 100x100`!  -size 100x100 `
          gradient: +matte -compose CopyOpacity -composite alpha_gradient.png
  magick convert alpha_gradient.png  +dither  -colors 256  alpha_colors_256.png
  magick convert alpha_gradient.png  +dither  -colors 64   alpha_colors_64.png
  magick convert alpha_gradient.png  +dither  -colors 15   alpha_colors_15.png 

#!/usr/bin/bash

#  magick convert xc:red xc:yellow xc:green1 xc:cyan xc:blue `
#          +append -filter Cubic -resize 100x100`!  -size 100x100 `
#          gradient: +matte -compose CopyOpacity -composite alpha_gradient.png
magick convert alpha_gradient_1.png +dither -colors 256 alpha_colors_256_1.png
magick convert alpha_gradient_1.png +dither -colors 64  alpha_colors_64_1.png
magick convert alpha_gradient_1.png +dither -colors 15  alpha_colors_15_1.png 

透明度が関係する場合、IM カラー量子化では、
完全に不透明なカラーや完全に透明なカラーが
選択されないことがあります。

#!/usr/bin/bash

  convert alpha_gradient.png  +dither  -colors 15 \
          -channel A -contrast-stretch 10%  alpha_colors_15n.png 

#!/usr/bin/bash

  magick convert alpha_gradient_1.png  +dither  -colors 15 `
          -channel A -contrast-stretch 10%  alpha_colors_15n_1.png

#!/usr/bin/bash

  convert alpha_gradient.png -quantize transparent \
                            +dither  -colors 15   alpha_colors_15qt.png 

#!/usr/bin/bash

  magick convert alpha_gradient_1.png -quantize transparent `
                            +dither  -colors 15   alpha_colors_15qt_1.png 

#!/usr/bin/bash

  convert alpha_gradient.png \
          -channel A   -threshold 50%       alpha_dither_threshold.gif
  convert alpha_gradient.png \
          -channel A -ordered-dither checks alpha_dither_checks.gif
  convert alpha_gradient.png \
          -channel A -ordered-dither o8x8   alpha_dither_ordered.gif
  convert alpha_gradient.png \
          -channel A -ordered-dither h8x8a  alpha_dither_halftone.gif

  convert alpha_gradient.png -channel RGBA -separate \
          \( +clone -monochrome \) \
          +swap +delete -combine alpha_dither_monochrome.gif
  convert alpha_gradient.png -channel RGBA -separate \
          \( +clone -dither FloydSteinberg -monochrome \) \
          +swap +delete -combine alpha_dither_monochrome_fs.gif
  convert alpha_gradient.png -channel RGBA -separate \
          \( +clone -remap pattern:gray50 \) \
          +swap +delete -combine  alpha_dither_map.gif
  convert alpha_gradient.png -channel RGBA -separate \
          \( +clone -dither FloydSteinberg -remap pattern:gray50 \) \
          +swap +delete -combine  alpha_dither_map_fs.gif 

#!/usr/bin/bash

  magick convert alpha_gradient_1.png `
          -channel A   -threshold 50%       alpha_dither_threshold_1.gif
  magick convert alpha_gradient_1.png `
          -channel A -ordered-dither checks alpha_dither_checks_1.gif
  magick convert alpha_gradient_1.png `
          -channel A -ordered-dither o8x8   alpha_dither_ordered_1.gif
  magick convert alpha_gradient_1.png `
          -channel A -ordered-dither h8x8a  alpha_dither_halftone_1.gif

  magick convert alpha_gradient_1.png -channel RGBA -separate `
          `( +clone -monochrome `) `
          +swap +delete -combine alpha_dither_monochrome_1.gif
  magick convert alpha_gradient_1.png -channel RGBA -separate `
          `( +clone -dither FloydSteinberg -monochrome `) `
          +swap +delete -combine alpha_dither_monochrome_fs_1.gif
  magick convert alpha_gradient_1.png -channel RGBA -separate `
          `( +clone -remap pattern:gray50 `) `
          +swap +delete -combine  alpha_dither_map_1.gif
  magick convert alpha_gradient_1.png -channel RGBA -separate `
          `( +clone -dither FloydSteinberg -remap pattern:gray50 `) `
          +swap +delete -combine  alpha_dither_map_fs_1.gif 

#!/usr/bin/bash

  convert -list dither 

None
FloydSteinberg
Riemersma 

#!/usr/bin/bash

  magick convert -list dither 

None
FloydSteinberg
Riemersma 

#!/usr/bin/bash

  convert colorwheel.png -dither Riemersma      -colors 16 dither_riemersma.gif
  convert colorwheel.png -dither FloydSteinberg -colors 16 dither_floyd.gif 

#!/usr/bin/bash

magick convert colorwheel.png -dither Riemersma  -colors 16 dither_riemersma.gif
magick convert colorwheel.png -dither FloydSteinberg -colors 16 dither_floyd.gif 

#!/usr/bin/bash

  convert -size 10x10 xc:'#999999' -scale 80x80  dither_not.gif
  convert -size 10x10 xc:'#999999' \
          -remap colortable.gif   -scale 80x80  dither.gif 

#!/usr/bin/bash

  magick convert -size 10x10 xc:'#999999' -scale 80x80  dither_not.gif
  magick convert -size 10x10 xc:'#999999' `
          -remap colortable.gif   -scale 80x80  dither.gif 

#!/usr/bin/bash

  convert -size 10x10 xc:'#999999'  -dither FloydSteinberg \
          -remap colortable.gif   -scale 80x80  dither_fs.gif 

#!/usr/bin/bash

  magick convert -size 10x10 xc:'#999999'  -dither FloydSteinberg `
          -remap colortable.gif   -scale 80x80  dither_fs.gif 

#!/usr/bin/bash

  convert -size 10x10 xc:'#999999' -draw 'fill #C28 point 2,2' \
          -remap colortable.gif   -scale 80x80   dither_modified.gif
  compare dither.gif dither_modified.gif dither_difference.gif 

　 　 　
　original　　　　one pixel　　　　　comparison

#!/usr/bin/bash

  magick convert -size 10x10 xc:'#999999' -draw 'fill #C28 point 2,2' `
          -remap colortable.gif   -scale 80x80   dither_modified.gif
  magick compare dither.gif dither_modified.gif dither_difference.gif 

　 　 　
　original　　　　one pixel　　　　　comparison

#!/usr/bin/bash

  convert -size 10x10 xc:'#999999' -draw 'fill #C28 point 2,2' \
          -dither FloydSteinberg -remap colortable.gif \
          -scale 80x80   dither_fs_modified.gif
  compare dither_fs.gif dither_fs_modified.gif dither_fs_difference.gif 

　 　 　
　original　　　　one pixel　　　　　comparison

#!/usr/bin/bash

  magick convert -size 10x10 xc:'#999999' -draw 'fill #C28 point 2,2' `
          -dither FloydSteinberg -remap colortable.gif `
          -scale 80x80   dither_fs_modified.gif
  magick compare dither_fs.gif dither_fs_modified.gif dither_fs_difference.gif 

　 　 　
　original　　　　one pixel　　　　　comparison

#!/usr/bin/bash

  convert -size 80x80 xc:'#999999' \
          \( +clone -draw 'fill #C28 point 2,2' \) \
          \( +clone -draw 'fill #28C point 2,2' \) \
   -remap colortable.gif  -set delay 50 -loop 0   dither_anim.gif
  convert dither_anim.gif -crop 10x10+40+40 +repage \
                          -scale 80x80     dither_anim_magnify.gif 

#!/usr/bin/bash

  magick convert -size 80x80 xc:'#999999' `
          `( +clone -draw 'fill #C28 point 2,2' `) `
          `( +clone -draw 'fill #28C point 2,2' `) `
   -remap colortable.gif  -set delay 50 -loop 0   dither_anim.gif
  magick convert dither_anim.gif -crop 10x10+40+40 +repage `
                          -scale 80x80     dither_anim_magnify.gif 

#!/usr/bin/bash

  convert -size 100x60 xc:SkyBlue \
          -fill DodgerBlue -draw 'circle 50,70 15,35' \
          -fill RoyalBlue  -draw 'circle 50,70 30,45' \
          -blur 0x5  -colors 64     speckle_gradient.gif 

#!/usr/bin/bash

  magick convert -size 100x60 xc:SkyBlue `
          -fill DodgerBlue -draw 'circle 50,70 15,35' `
          -fill RoyalBlue  -draw 'circle 50,70 30,45' `
          -blur 0x5  -colors 64     speckle_gradient.gif 

#!/usr/bin/bash

  convert -size 100x60 xc:SkyBlue \
          -fill DodgerBlue -draw 'circle 50,70 15,35' \
          -fill RoyalBlue  -draw 'circle 50,70 30,45' -blur 0x5 \
          -fill white -draw 'rectangle 40,40 60,55' \
          -colors 64   speckle_problem.gif 

#!/usr/bin/bash

  magick convert -size 100x60 xc:SkyBlue `
          -fill DodgerBlue -draw 'circle 50,70 15,35' `
          -fill RoyalBlue  -draw 'circle 50,70 30,45' -blur 0x5 `
          -fill white -draw 'rectangle 40,40 60,55' `
          -colors 64   speckle_problem.gif 

#!/usr/bin/bash

  convert speckle_problem.gif -crop 15x15+75+0 +repage \
          -scale 90x90    speckle_prob_mag.gif 

#!/usr/bin/bash

  magick convert speckle_problem.gif -crop 15x15+75+0 +repage `
          -scale 90x90    speckle_prob_mag.gif 

#!/usr/bin/bash

  convert -size 100x60 xc:SkyBlue \
          -fill DodgerBlue -draw 'circle 50,70 15,35' \
          -fill RoyalBlue  -draw 'circle 50,70 30,45' -blur 0x5 \
          -fill white -draw 'circle 50,45 40,40' \
          -colors 64  speckle_fixed.gif 

#!/usr/bin/bash

  magick convert -size 100x60 xc:SkyBlue `
          -fill DodgerBlue -draw 'circle 50,70 15,35' `
          -fill RoyalBlue  -draw 'circle 50,70 30,45' -blur 0x5 `
          -fill white -draw 'circle 50,45 40,40' `
          -colors 64  speckle_fixed.gif 

#!/usr/bin/bash

  convert speckle_fixed.gif -crop 15x15+85+0 +repage \
          -scale 90x90    speckle_fix_mag.gif 

#!/usr/bin/bash

  magick convert speckle_fixed.gif -crop 15x15+85+0 +repage `
          -scale 90x90    speckle_fix_mag.gif 

#!/usr/bin/bash

  convert -size 100x60 xc:SkyBlue \
          -fill DodgerBlue -draw 'circle 50,70 15,35' \
          -fill RoyalBlue  -draw 'circle 50,70 30,45' -blur 0x5 \
          -colors 63 \
          -fill white -draw 'rectangle 40,40 60,55'  speckle_perfect.gif 

#!/usr/bin/bash

  magick convert -size 100x60 xc:SkyBlue `
          -fill DodgerBlue -draw 'circle 50,70 15,35' `
          -fill RoyalBlue  -draw 'circle 50,70 30,45' -blur 0x5 `
          -colors 63 `
          -fill white -draw 'rectangle 40,40 60,55'  speckle_perfect.gif 

#!/usr/bin/bash

  convert  logo.png  -monochrome     monochrome.gif 

#!/usr/bin/bash

  magick convert  logo.png  -monochrome     monochrome.gif 

#!/usr/bin/bash

  convert -size 15x640 gradient: -rotate 90 \
          -monochrome     monochrome_gradient.gif 

#!/usr/bin/bash

  magick convert -size 15x640 gradient: -rotate 90 `
          -monochrome     monochrome_gradient.gif 

#!/usr/bin/bash

  convert  logo.png  -remap pattern:gray50  mono_remap.gif
  convert -size 15x640 gradient: -rotate 90 \
         -remap pattern:gray50     mono_remap_gradient.gif 

#!/usr/bin/bash

  magick convert  logo.png  -remap pattern:gray50  mono_remap.gif
  magick convert -size 15x640 gradient: -rotate 90 `
         -remap pattern:gray50     mono_remap_gradient.gif 

#!/usr/bin/bash

  convert xc:gray20  xc:white  +append   ctrl_colors.gif
  convert logo.png -colorspace Gray \
      -remap ctrl_colors.gif  -normalize  mono_remap_ctrl.gif
  convert -size 15x640 gradient: -rotate 90 \
     -remap ctrl_colors.gif  -normalize  mono_remap_grad_ctrl.gif 

#!/usr/bin/bash

  magick convert xc:gray20  xc:white  +append   ctrl_colors.gif
  magick convert logo.png -colorspace Gray `
      -remap ctrl_colors.gif  -normalize  mono_remap_ctrl.gif
  magick convert -size 15x640 gradient: -rotate 90 `
     -remap ctrl_colors.gif  -normalize  mono_remap_grad_ctrl.gif 

#!/usr/bin/bash

  convert  logo.png   -colors 2 -colorspace gray  -normalize \
                                       colors_monochrome.gif 

#!/usr/bin/bash

magick convert  logo.png  -colors 2 -colorspace gray  -normalize `
                                       colors_monochrome.gif 

#!/usr/bin/bash

  convert -size 20x640 gradient:red-blue -rotate 90    gradient_rb.png
  convert gradient_rb.png   -colors 2 -colorspace gray \
                            -normalize        colors_threshold.gif
  convert gradient_rb.png   -monochrome       mono_threshold.gif 

#!/usr/bin/bash

  magick convert -size 20x640 gradient:red-blue -rotate 90    gradient_rb.png
  magick convert gradient_rb.png   -colors 2 -colorspace gray `
                            -normalize        colors_threshold.gif
  magick convert gradient_rb.png   -monochrome       mono_threshold.gif 

#!/usr/bin/bash

  convert  logo.png -colorspace gray   -colors 2  -normalize \
                                   monochrome_equivelent.gif 

#!/usr/bin/bash

magick convert  logo.png -colorspace gray  -colors 2  -normalize `
                                   monochrome_equivelent.gif 

#!/usr/bin/bash

  convert  logo.png  -colorspace gray  +dither  -colors 2 \
                        -normalize  threshold_two_grays.gif 

#!/usr/bin/bash

  magick convert  logo.png  -colorspace gray  +dither `
              -colors 2  -normalize  threshold_two_grays.gif 

#!/usr/bin/bash

  convert  logo.png  +dither  -colors 2 \
    -colorspace gray -normalize  threshold_two_color.gif 

#!/usr/bin/bash

  magick convert  logo.png  +dither  -colors 2 `
    -colorspace gray -normalize  threshold_two_color.gif 

#!/usr/bin/bash

  convert logo.png  -dither None       -remap colortable.gif  remap_logo_no.gif
  convert logo.png  -dither Riemersma  -remap colortable.gif  remap_logo_rm.gif
  convert logo.png  -dither FloydSteinberg \
                                       -remap colortable.gif  remap_logo_fs.gif 

#!/usr/bin/bash

  magick convert logo.png  -dither None       -remap colortable.gif  remap_logo_no.gif
  magick convert logo.png  -dither Riemersma  -remap colortable.gif  remap_logo_rm.gif
  magick convert logo.png  -dither FloydSteinberg `
                                       -remap colortable.gif  remap_logo_fs.gif 

#!/usr/bin/bash

  convert logo.png         -remap netscape:  remap_netscape.gif
  convert logo.png +dither -remap netscape:  remap_netscape_nd.gif 

#!/usr/bin/bash

  magick convert logo.png         -remap netscape:  remap_netscape.gif
  magick convert logo.png +dither -remap netscape:  remap_netscape_nd.gif 

#!/usr/bin/bash

convert -size 16x16 xc: -channel R -fx '(i%8)/7' \
                        -channel G -fx '(j%8)/7' \
                        -channel B -fx '((i>>3&1)|(j>>2&2))/3' \
              -scale 600% colormap_332.png 

#!/usr/bin/bash

magick convert -size 16x16 xc: -channel R -fx '(i%8)/7' `
                        -channel G -fx '(j%8)/7' `
                        -channel B -fx '((i>>3&1)|(j>>2&2))/3' `
              -scale 600% colormap_332.png 

#!/usr/bin/bash

  convert netscape: -scale 50%  +dither  -posterize 2   posterize_2_ns.gif
  convert netscape: -scale 50%  +dither  -posterize 3   posterize_3_ns.gif
  convert netscape: -scale 50%  +dither  -posterize 6   posterize_6_ns.gif 

#!/usr/bin/bash

magick convert netscape: -scale 50%  +dither  -posterize 2   posterize_2_ns.gif
magick convert netscape: -scale 50%  +dither  -posterize 3   posterize_3_ns.gif
magick convert netscape: -scale 50%  +dither  -posterize 6   posterize_6_ns.gif 

#!/usr/bin/bash

  convert -size 20x640  gradient: -rotate 90  gradient.png
  convert gradient.png  +dither  -posterize 5   posterize_gradient.gif 

#!/usr/bin/bash

  magick convert -size 20x640  gradient: -rotate 90  gradient.png
  magick convert gradient.png  +dither  -posterize 5   posterize_gradient.gif 

#!/usr/bin/bash

  convert logo.png  +dither -posterize 2  posterize_logo.gif
  convert logo.png          -posterize 2  posterize_logo_dither.gif
  convert logo.png          -posterize 6  posterize_6_logo.gif 

#!/usr/bin/bash

  magick convert logo.png  +dither -posterize 2  posterize_logo.gif
  magick convert logo.png          -posterize 2  posterize_logo_dither.gif
  magick convert logo.png          -posterize 6  posterize_6_logo.gif 

#!/usr/bin/bash

  convert colorwheel.png  +dither  -posterize 2   posterize_2_cw.gif
  convert colorwheel.png  +dither  -posterize 3   posterize_3_cw.gif
  convert colorwheel.png  +dither  -posterize 6   posterize_6_cw.gif 

#!/usr/bin/bash

  magick convert colorwheel.png  +dither  -posterize 2   posterize_2_cw.gif
  magick convert colorwheel.png  +dither  -posterize 3   posterize_3_cw.gif
  magick convert colorwheel.png  +dither  -posterize 6   posterize_6_cw.gif 

#!/usr/bin/bash

  convert colorwheel.png  -ordered-dither o8x8,2   posterize_2_od.gif
  convert colorwheel.png  -ordered-dither o8x8,3   posterize_3_od.gif
  convert colorwheel.png  -ordered-dither o8x8,6   posterize_6_od.gif 

#!/usr/bin/bash

  magick convert colorwheel.png  -ordered-dither o8x8,2   posterize_2_od.gif
  magick convert colorwheel.png  -ordered-dither o8x8,3   posterize_3_od.gif
  magick convert colorwheel.png  -ordered-dither o8x8,6   posterize_6_od.gif 

#!/usr/bin/bash

  convert logo.png     -threshold   -1   threshold_0.gif
  convert logo.png     -threshold  25%   threshold_25.gif
  convert logo.png     -threshold  50%   threshold_50.gif
  convert logo.png     -threshold  75%   threshold_75.gif
  convert logo.png     -threshold 100%   threshold_100.gif 

#!/usr/bin/bash

  magick convert logo.png     -threshold   -1   threshold_0.gif
  magick convert logo.png     -threshold  25%   threshold_25.gif
  magick convert logo.png     -threshold  50%   threshold_50.gif
  magick convert logo.png     -threshold  75%   threshold_75.gif
  magick convert logo.png     -threshold 100%   threshold_100.gif 

#!/usr/bin/bash

  convert logo.png  -threshold   0    threshold_black.gif 

#!/usr/bin/bash

  magick convert logo.png  -threshold   0    threshold_black.gif 

#!/usr/bin/bash

  convert  logo.png  -negate -threshold 0 -negate threshold_white.gif 

#!/usr/bin/bash

  magick convert  logo.png  -negate -threshold 0 -negate threshold_white.gif 

#!/usr/bin/bash

  convert  logo.png  -channel R -threshold 50% \
                     -channel G -threshold 50% \
                     -channel B -threshold 50% \
     threshold_posterize.gif 

#!/usr/bin/bash

  magick convert  logo.png  -channel R -threshold 50% `
                     -channel G -threshold 50% `
                     -channel B -threshold 50% `
     threshold_posterize.gif 

#!/usr/bin/bash

  convert  logo.png  +dither  -colors 2  \
          -colorspace gray -normalize threshold_two_color.gif 

#!/usr/bin/bash

  magick convert  logo.png  +dither  -colors 2  `
        -colorspace gray -normalize  threshold_two_color.gif 

#!/usr/bin/bash

  convert  logo.png  -random-threshold  0x100%  \
                                      random_posterize.gif 

#!/usr/bin/bash

  magick convert  logo.png  -random-threshold  0x100%  `
                                       random_posterize.gif 

#!/usr/bin/bash

  convert  logo.png  -colorspace Gray \
           -random-threshold  0x100%  random_greyscale.gif 

#!/usr/bin/bash

magick convert  logo.png  -colorspace Gray `
            -random-threshold  0x100%  random_greyscale.gif 

#!/usr/bin/bash

  convert logo.png  -colorspace Gray -channel B \
    -random-threshold 0x100%    -separate   random_monochome.gif 

#!/usr/bin/bash

  magick convert logo.png  -colorspace Gray -channel B `
    -random-threshold 0x100%    -separate   random_monochome.gif 

#!/usr/bin/bash

  convert  logo.png  -channel All \
                     -random-threshold 0x100% random_all.gif 

#!/usr/bin/bash

  magick convert  logo.png  -channel All `
                       -random-threshold 0x100% random_all.gif 

#!/usr/bin/bash

  convert -size 20x640  gradient: -rotate 90  gradient.png
  convert gradient.png  -channel All \
                        -random-threshold 0x100%  random_grad_0x100.gif
  convert gradient.png  -channel All \
                        -random-threshold 10x90%  random_grad_10x90.gif
  convert gradient.png  -channel All \
                        -random-threshold 25x75%  random_grad_25x75.gif
  convert gradient.png  -channel All \
                        -random-threshold 50x50%  random_grad_50x50.gif 

#!/usr/bin/bash

  magick convert -size 20x640  gradient: -rotate 90  gradient.png
  magick convert gradient.png  -channel All `
                        -random-threshold 0x100%  random_grad_0x100.gif
  magick convert gradient.png  -channel All `
                        -random-threshold 10x90%  random_grad_10x90.gif
  magick convert gradient.png  -channel All `
                        -random-threshold 25x75%  random_grad_25x75.gif
  magick convert gradient.png  -channel All `
                        -random-threshold 50x50%  random_grad_50x50.gif 

#!/usr/bin/bash

  convert  logo.png  -channel All \
                     -random-threshold 30x80%  random_30x80.gif 

#!/usr/bin/bash

  magick convert  logo.png  -channel All `
                        -random-threshold 30x80%  random_30x80.gif 

#!/usr/bin/bash

  convert logo.png    -ordered-dither o2x2    logo_o2x2.gif
  convert logo.png    -ordered-dither o3x3    logo_o3x3.gif
  convert logo.png    -ordered-dither o4x4    logo_o4x4.gif
  convert logo.png    -ordered-dither o8x8    logo_o8x8.gif 

#!/usr/bin/bash

  magick convert logo.png    -ordered-dither o2x2    logo_o2x2.gif
  magick convert logo.png    -ordered-dither o3x3    logo_o3x3.gif
  magick convert logo.png    -ordered-dither o4x4    logo_o4x4.gif
  magick convert logo.png    -ordered-dither o8x8    logo_o8x8.gif 

#!/usr/bin/bash

  convert logo.png -colorspace Gray  -ordered-dither o2x2  logo_bw_o2x2.gif
  convert logo.png -colorspace Gray  -ordered-dither o3x3  logo_bw_o3x3.gif
  convert logo.png -colorspace Gray  -ordered-dither o4x4  logo_bw_o4x4.gif
  convert logo.png -colorspace Gray  -ordered-dither o8x8  logo_bw_o8x8.gif 

#!/usr/bin/bash

magick convert logo.png -colorspace Gray  -ordered-dither o2x2  logo_bw_o2x2.gif
magick convert logo.png -colorspace Gray  -ordered-dither o3x3  logo_bw_o3x3.gif
magick convert logo.png -colorspace Gray  -ordered-dither o4x4  logo_bw_o4x4.gif
magick convert logo.png -colorspace Gray  -ordered-dither o8x8  logo_bw_o8x8.gif 

#!/usr/bin/bash

  # Threshold Non-Dither / Minimal Checkerboard Dither
  convert gradient.png   -ordered-dither threshold  od_threshold.gif
  convert gradient.png   -ordered-dither checks     od_checks.gif
  # Diffused Pixel Dither
  convert gradient.png   -ordered-dither o2x2       od_o2x2.gif
  convert gradient.png   -ordered-dither o3x3       od_o3x3.gif
  convert gradient.png   -ordered-dither o4x4       od_o4x4.gif
  convert gradient.png   -ordered-dither o8x8       od_o8x8.gif 

#!/usr/bin/bash

  # Threshold Non-Dither / Minimal Checkerboard Dither
  magick convert gradient.png   -ordered-dither threshold  od_threshold.gif
  magick convert gradient.png   -ordered-dither checks     od_checks.gif
  # Diffused Pixel Dither
  magick convert gradient.png   -ordered-dither o2x2       od_o2x2.gif
  magick convert gradient.png   -ordered-dither o3x3       od_o3x3.gif
  magick convert gradient.png   -ordered-dither o4x4       od_o4x4.gif
  magick convert gradient.png   -ordered-dither o8x8       od_o8x8.gif 

• 1. ストレートな「50%のしきい値」非ディザリングで、余分なグレーレベルは生成されず、
  
  
• 2. 「チェック」またはチェッカーボードディザパターンは、単一のパターンを挿入して、結果のグラデーションに余分な「擬似レベル」を追加します。
  
  

#!/usr/bin/bash

  # Halftone Screen (45 degree angle)
  convert logo.png   -ordered-dither h4x4a    logo_h4x4a.gif
  convert logo.png   -ordered-dither h6x6a    logo_h6x6a.gif
  convert logo.png   -ordered-dither h8x8a    logo_h8x8a.gif
  # Halftone Screen (orthogonal)
  convert logo.png   -ordered-dither h4x4o    logo_h4x4o.gif
  convert logo.png   -ordered-dither h6x6o    logo_h6x6o.gif
  convert logo.png   -ordered-dither h8x8o    logo_h8x8o.gif 

#!/usr/bin/bash

  # Halftone Screen (45 degree angle)
  magick convert logo.png   -ordered-dither h4x4a    logo_h4x4a.gif
  magick convert logo.png   -ordered-dither h6x6a    logo_h6x6a.gif
  magick convert logo.png   -ordered-dither h8x8a    logo_h8x8a.gif
  # Halftone Screen (orthogonal)
  magick convert logo.png   -ordered-dither h4x4o    logo_h4x4o.gif
  magick convert logo.png   -ordered-dither h6x6o    logo_h6x6o.gif
  magick convert logo.png   -ordered-dither h8x8o    logo_h8x8o.gif 

#!/usr/bin/bash

  # Halftone Screen (45 degree angle)
  convert logo.png -colorspace Gray  -ordered-dither h4x4a logo_bw_h4x4a.gif
  convert logo.png -colorspace Gray  -ordered-dither h6x6a logo_bw_h6x6a.gif
  convert logo.png -colorspace Gray  -ordered-dither h8x8a logo_bw_h8x8a.gif
  # Halftone Screen (orthogonal)
  convert logo.png -colorspace Gray  -ordered-dither h4x4o logo_bw_h4x4o.gif
  convert logo.png -colorspace Gray  -ordered-dither h6x6o logo_bw_h6x6o.gif
  convert logo.png -colorspace Gray  -ordered-dither h8x8o logo_bw_h8x8o.gif 

#!/usr/bin/bash

  # Halftone Screen (45 degree angle)
  magick convert logo.png -colorspace Gray  -ordered-dither h4x4a logo_bw_h4x4a.gif
  magick convert logo.png -colorspace Gray  -ordered-dither h6x6a logo_bw_h6x6a.gif
  magick convert logo.png -colorspace Gray  -ordered-dither h8x8a logo_bw_h8x8a.gif
  # Halftone Screen (orthogonal)
  magick convert logo.png -colorspace Gray  -ordered-dither h4x4o logo_bw_h4x4o.gif
  magick convert logo.png -colorspace Gray  -ordered-dither h6x6o logo_bw_h6x6o.gif
  magick convert logo.png -colorspace Gray  -ordered-dither h8x8o logo_bw_h8x8o.gif 

#!/usr/bin/bash

  # Halftone Screen (45 degree angle)
  convert gradient.png   -ordered-dither h4x4a      od_h4x4a.gif
  convert gradient.png   -ordered-dither h6x6a      od_h6x6a.gif
  convert gradient.png   -ordered-dither h8x8a      od_h8x8a.gif
  # Halftone Screen (orthogonal)
  convert gradient.png   -ordered-dither h4x4o      od_h4x4o.gif
  convert gradient.png   -ordered-dither h6x6o      od_h6x6o.gif
  convert gradient.png   -ordered-dither h8x8o      od_h8x8o.gif
  convert gradient.png   -ordered-dither h16x16o    od_h16x16o.gif
  # Circle Halftones (black and white)
  convert gradient.png   -ordered-dither c7x7b      od_c7x7b.gif
  convert gradient.png   -ordered-dither c7x7w      od_c7x7w.gif 

#!/usr/bin/bash

  # Halftone Screen (45 degree angle)
  magick convert gradient.png   -ordered-dither h4x4a      od_h4x4a.gif
  magick convert gradient.png   -ordered-dither h6x6a      od_h6x6a.gif
  magick convert gradient.png   -ordered-dither h8x8a      od_h8x8a.gif
  # Halftone Screen (orthogonal)
  magick convert gradient.png   -ordered-dither h4x4o      od_h4x4o.gif
  magick convert gradient.png   -ordered-dither h6x6o      od_h6x6o.gif
  magick convert gradient.png   -ordered-dither h8x8o      od_h8x8o.gif
  magick convert gradient.png   -ordered-dither h16x16o    od_h16x16o.gif
  # Circle Halftones (black and white)
  magick convert gradient.png   -ordered-dither c7x7b      od_c7x7b.gif
  magick convert gradient.png   -ordered-dither c7x7w      od_c7x7w.gif 

#!/usr/bin/bash

  convert colorwheel.png \
          -set option:distort:viewport '%wx%h+0+0' \
          -colorspace CMYK -separate null: \
          \( -size 2x2 xc: \( +clone -negate \) \
          +append \( +clone -negate \) -append \) \
          -virtual-pixel tile -filter gaussian \
          \( +clone -distort SRT 60 \) +swap \
          \( +clone -distort SRT 30 \) +swap \
          \( +clone -distort SRT 45 \) +swap \
          \( +clone -distort SRT 0 \)  +swap +delete \
          -compose Overlay -layers composite \
          -set colorspace CMYK -combine -colorspace RGB \
          offset_colorwheel.png 

#!/usr/bin/bash

  magick convert colorwheel.png `
          -set option:distort:viewport '%wx%h+0+0' `
          -colorspace CMYK -separate null: `
          `( -size 2x2 xc: `( +clone -negate `) `
          +append `( +clone -negate `) -append `) `
          -virtual-pixel tile -filter gaussian `
          `( +clone -distort SRT 60 `) +swap `
          `( +clone -distort SRT 30 `) +swap `
          `( +clone -distort SRT 45 `) +swap `
          `( +clone -distort SRT 0 `)  +swap +delete `
          -compose Overlay -layers composite `
          -set colorspace CMYK -combine -colorspace RGB `
          offset_colorwheel.png 

#!/usr/bin/bash

  convert parrots_med.png  \
          -set option:distort:viewport '%wx%h+0+0' \
          -colorspace CMYK -separate null: \
          \( -size 2x2 xc: \( +clone -negate \) \
          +append \( +clone -negate \) -append \) \
          -virtual-pixel tile -filter gaussian \
          \( +clone -distort SRT 2,60 \) +swap \
          \( +clone -distort SRT 2,30 \) +swap \
          \( +clone -distort SRT 2,45 \) +swap \
          \( +clone -distort SRT 2,0  -blur 0x0.7 \) +swap +delete \
          -compose Overlay -layers composite \
          -set colorspace CMYK -combine -colorspace RGB \
          offset_parrots.png 

#!/usr/bin/bash

  magick convert parrots_med.png  `
          -set option:distort:viewport '%wx%h+0+0' `
          -colorspace CMYK -separate null: `
          `( -size 2x2 xc: `( +clone -negate `) `
          +append `( +clone -negate `) -append `) `
          -virtual-pixel tile -filter gaussian `
          `( +clone -distort SRT 2,60 `) +swap `
          `( +clone -distort SRT 2,30 `) +swap `
          `( +clone -distort SRT 2,45 `) +swap `
          `( +clone -distort SRT 2,0  -blur 0x0.7 `) +swap +delete `
          -compose Overlay -layers composite `
          -set colorspace CMYK -combine -colorspace RGB `
          offset_parrots.png 

#!/usr/bin/bash

  identify -list threshold 

   Threshold Maps for Ordered Dither Operations

Path: /etc/ImageMagick-6/thresholds.xml

Map              Alias        Description
----------------------------------------------------
threshold        1x1          Threshold 1x1 (non-dither)
checks           2x1          Checkerboard 2x1 (dither)
o2x2             2x2          Ordered 2x2 (dispersed)
o3x3             3x3          Ordered 3x3 (dispersed)
o4x4             4x4          Ordered 4x4 (dispersed)
o8x8             8x8          Ordered 8x8 (dispersed)
h4x4a            4x1          Halftone 4x4 (angled)
h6x6a            6x1          Halftone 6x6 (angled)
h8x8a            8x1          Halftone 8x8 (angled)
h4x4o                         Halftone 4x4 (orthogonal)
h6x6o                         Halftone 6x6 (orthogonal)
h8x8o                         Halftone 8x8 (orthogonal)
h16x16o                       Halftone 16x16 (orthogonal)
c5x5b            c5x5         Circles 5x5 (black)
c5x5w                         Circles 5x5 (white)
c6x6b            c6x6         Circles 6x6 (black)
c6x6w                         Circles 6x6 (white)
c7x7b            c7x7         Circles 7x7 (black)
c7x7w                         Circles 7x7 (white) 

#!/usr/bin/bash

  magick identify -list threshold 

   Threshold Maps for Ordered Dither Operations

Path: C:\Program Files\ImageMagick-7.1.0-Q16\thresholds.xml

Map              Alias        Description
----------------------------------------------------
threshold        1x1          Threshold 1x1 (non-dither)
checks           2x1          Checkerboard 2x1 (dither)
o2x2             2x2          Ordered 2x2 (dispersed)
o3x3             3x3          Ordered 3x3 (dispersed)
o4x4             4x4          Ordered 4x4 (dispersed)
o8x8             8x8          Ordered 8x8 (dispersed)
h4x4a            4x1          Halftone 4x4 (angled)
h6x6a            6x1          Halftone 6x6 (angled)
h8x8a            8x1          Halftone 8x8 (angled)
h4x4o                         Halftone 4x4 (orthogonal)
h6x6o                         Halftone 6x6 (orthogonal)
h8x8o                         Halftone 8x8 (orthogonal)
h16x16o                       Halftone 16x16 (orthogonal)
c5x5b            c5x5         Circles 5x5 (black)
c5x5w                         Circles 5x5 (white)
c6x6b            c6x6         Circles 6x6 (black)
c6x6w                         Circles 6x6 (white)
c7x7b            c7x7         Circles 7x7 (black)
c7x7w                         Circles 7x7 (white) 

  <threshold map="diag5x5" alias="diag">
    <description>Simple Diagonal Line Dither</description>
      <levels width="5" height="5" divisor="6">
          4 2 1 3 5
          2 1 3 5 4
          1 3 5 4 2
          3 5 4 2 1
          5 4 2 1 3
      </levels>
 </threshold> 

#!/usr/bin/bash

  convert gradient.png   -ordered-dither diag      od_diag.gif 

#!/usr/bin/bash

  magick convert gradient.png   -ordered-dither diag      od_diag.gif 

#!/usr/bin/bash

  convert -size 70x60 xc:none -font Candice -pointsize 50 \
          -fill black -annotate +10+45 'A' -channel RGBA  -blur 0x5 \
          -fill white -stroke black -draw "text 5,40 'A'"   shadow.png

  convert shadow.png  -channel A  -ordered-dither diag   shadow_diag.gif 

#!/usr/bin/bash

  magick convert -size 70x60 xc:none -font Forte -pointsize 50 `
          -fill black -annotate +10+45 'A' -channel RGBA  -blur 0x5 `
          -fill white -stroke black -draw "text 5,40 'A'"   shadow.png

  magick convert shadow.png  -channel A  -ordered-dither diag   shadow_diag.gif 

#!/usr/bin/bash

  convert gradient.png   -ordered-dither threshold,6  od_threshold_6.gif
  convert gradient.png   -ordered-dither checks,6     od_checks_6.gif
  convert gradient.png   -ordered-dither o2x2,6       od_o2x2_6.gif
  convert gradient.png   -ordered-dither o4x4,6       od_o4x4_6.gif
  convert gradient.png   -ordered-dither o8x8,6       od_o8x8_6.gif 

#!/usr/bin/bash

  magick convert gradient.png   -ordered-dither threshold,6  od_threshold_6.gif
  magick convert gradient.png   -ordered-dither checks,6     od_checks_6.gif
  magick convert gradient.png   -ordered-dither o2x2,6       od_o2x2_6.gif
  magick convert gradient.png   -ordered-dither o4x4,6       od_o4x4_6.gif
  magick convert gradient.png   -ordered-dither o8x8,6       od_o8x8_6.gif 

#!/usr/bin/bash

  convert gradient.png   -ordered-dither o8x8,8,8,4   od_o8x8_884.gif 

#!/usr/bin/bash

  magick convert gradient.png   -ordered-dither o8x8,8,8,4   od_o8x8_884.gif 

#!/usr/bin/bash

  convert logo.png  -ordered-dither o8x8        logo_o8x8_2.gif
  convert logo.png  -posterize 2                logo_posterize_2.gif
  convert logo.png  -ordered-dither o8x8,6      logo_o8x8_6.gif
  convert logo.png  -posterize 6                logo_posterize_6.gif
  convert logo.png  -ordered-dither o8x8,8,8,4  logo_o8x8_332.gif
  convert logo.png  -remap colormap_332.png     logo_remap_332.gif 

#!/usr/bin/bash

  magick convert logo.png  -ordered-dither o8x8        logo_o8x8_2.gif
  magick convert logo.png  -posterize 2                logo_posterize_2.gif
  magick convert logo.png  -ordered-dither o8x8,6      logo_o8x8_6.gif
  magick convert logo.png  -posterize 6                logo_posterize_6.gif
  magick convert logo.png  -ordered-dither o8x8,8,8,4  logo_o8x8_332.gif
  magick convert logo.png  -remap colormap_332.png     logo_remap_332.gif 

#!/usr/bin/bash

  convert logo.png -ordered-dither o8x8,6 -format %k info: 

61 

#!/usr/bin/bash

  magick convert logo.png -ordered-dither o8x8,6 -format %k info: 

61 

#!/usr/bin/bash

  convert logo.png -ordered-dither o8x8,13 -format %k info: 

212 

#!/usr/bin/bash

  magick convert logo.png -ordered-dither o8x8,13 -format %k info: 

212 

#!/usr/bin/bash

  convert logo.png -ordered-dither o8x8,13  logo_o8x8_13.gif 

#!/usr/bin/bash

magick convert logo.png -ordered-dither o8x8,13 logo_o8x8_13.gif 

#!/usr/bin/bash

  convert -size 2x2 xc:black \
          \( +clone -draw 'fill white line 0,0 1,0' \) \
          xc:white     dpat_hlines2x2.gif
  montage dpat_hlines2x2.gif    -tile x1 -background none -frame 2 \
          -filter box  -geometry 32x32+5+0    dpat_hlines2x2_imgs.gif 

#!/usr/bin/bash

  magick convert -size 2x2 xc:black `
          `( +clone -draw 'fill white line 0,0 1,0' `) `
          xc:white     dpat_hlines2x2.gif
  magick montage dpat_hlines2x2.gif    -tile x1 -background none -frame 2 `
          -filter box  -geometry 32x32+5+0    dpat_hlines2x2_imgs.gif 

#!/usr/bin/bash

  convert gradient.png   dpat_hlines2x2.gif \
    -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1]' dgrad_hlines2x2.gif 

convert: no such image `u[floor((n-1.0*1)*u)+1]' @ error/fx.c/FxGetSymbol/1446.  

#!/usr/bin/bash

  magick convert gradient.png   dpat_hlines2x2.gif `
    -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1]' dgrad_hlines2x2.gif 

#!/usr/bin/bash

  convert shadow.png dpat_hlines2x2.gif  -channel A \
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1].g' \
          shadow_dpat_hlines2x2.gif 

convert: no such image `u[floor((n-1.0*1)*u)+1].g' @ error/fx.c/FxGetSymbol/1446.

#!/usr/bin/bash

  magick convert shadow.png dpat_hlines2x2.gif  -channel A `
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1].g' `
          shadow_dpat_hlines2x2.gif 

  <threshold map="hlines2x2" alias="hlines2">
    <description>Horizontal Lines 2x2</description>
      <levels width="2" height="2" divisor="3">
          1   1
          2   2
      </levels>
  </threshold> 

#!/usr/bin/bash

  convert gradient.png  -ordered-dither hlines2x2  od_hlines2x2.gif
  convert shadow.png  -channel A \
          -ordered-dither hlines2x2   shadow_hlines2x2.gif 

#!/usr/bin/bash

  magick convert gradient.png  -ordered-dither hlines2x2  od_hlines2x2.gif
  magick convert shadow.png  -channel A `
          -ordered-dither hlines2x2   shadow_hlines2x2.gif 

  <threshold map="hlines2x2a">
    <description>Horizontal Lines 2x2 (bounds adjusted)</description>
      <levels width="2" height="2" divisor="10">
          3   3
          9   9
      </levels>
  </threshold> 

#!/usr/bin/bash

  convert gradient.png  -ordered-dither hlines2x2a  od_hlines2x2a.gif
  convert shadow.png -channel A \
          -ordered-dither hlines2x2a  shadow_hlines2x2a.gif 

#!/usr/bin/bash

  magick convert gradient.png  -ordered-dither hlines2x2a  od_hlines2x2a.gif
  magick convert shadow.png -channel A `
          -ordered-dither hlines2x2a  shadow_hlines2x2a.gif 

#!/usr/bin/bash

  montage dpat_hlines.gif   -filter box   -geometry 60x20+2+0 \
          -tile x1 -background none  -frame 2   dpat_hlines_images.gif
  convert gradient.png  dpat_hlines.gif  \
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1]' \
          dgrad_dpat_hlines.gif
  convert shadow.png dpat_hlines.gif  -channel A \
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1].g' \
          shadow_dpat_hlines.gif 

convert: no such image `u[floor((n-1.0*1)*u)+1]' @ error/fx.c/FxGetSymbol/1446.
convert: no such image `u[floor((n-1.0*1)*u)+1].g' @ error/fx.c/FxGetSymbol/1446.  

#!/usr/bin/bash

  magick montage dpat_hlines.gif   -filter box   -geometry 60x20+2+0 `
          -tile x1 -background none  -frame 2   dpat_hlines_images.gif
  magick convert gradient.png  dpat_hlines.gif  `
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1]' `
          dgrad_dpat_hlines.gif
  magick convert shadow.png dpat_hlines.gif  -channel A `
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1].g' `
          shadow_dpat_hlines.gif 

#!/usr/bin/bash

  convert -size 120x55 xc:white  -draw 'fill #777 ellipse 50,43 30,5 0,360' \
          -motion-blur 0x15+180   -blur 0x2      sphere_shadow.png
  convert sphere_shadow.png dpat_hlines.gif \
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1]' \
          sphere_shadow_dither.gif
  convert sphere_shadow_dither.gif   -fill red  -stroke firebrick \
          -draw 'circle 35,25 35,5'     sphere_shadow_hlines.gif 

convert: no such image `u[floor((n-1.0*1)*u)+1]' @ error/fx.c/FxGetSymbol/1446.  

#!/usr/bin/bash

  magick convert -size 120x55 xc:white  -draw 'fill #777 ellipse 50,43 30,5 0,360' `
          -motion-blur 0x15+180   -blur 0x2      sphere_shadow.png
  magick convert sphere_shadow.png dpat_hlines.gif `
          -virtual-pixel tile  -fx 'u[floor((n-1)*u)+1]' `
          sphere_shadow_dither.gif
  magick convert sphere_shadow_dither.gif   -fill red  -stroke firebrick `
          -draw 'circle 35,25 35,5'     sphere_shadow_hlines.gif 

convert: ImgNum 10 bad for ImgListLen 10 @ error/fx.c/ChkImgNum/3028.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.
convert: Empty expression in parentheses at '*u)+1]' @ error/fx.c/GetOperand/2089.
convert: For function 'floor' expected 1 arguments, found too few (0) at '*u)+1]' @ error/fx.c/GetFunction/1893.
convert: For function 'u', arguments don't end with ']' at '*u)+1]' @ error/fx.c/GetFunction/1906.  

#!/usr/bin/bash

  convert -size 1x10 gradient: -flip -crop 1x1 \
    +repage -delete 0,-1 \
    -scale 12x4\! null: \( dpat_hlines.gif -delete 0 \) \
    +matte -compose CopyOpacity -layers Composite \
    -reverse -compose Over -flatten +matte dmap_hlines.png 

#!/usr/bin/bash

  magick convert -size 1x10 gradient: -flip -crop 1x1 `
    +repage -delete 0,-1 `
    -scale 12x4`! null: `( dpat_hlines.gif -delete 0 `) `
    +matte -compose CopyOpacity -layers Composite `
    -reverse -compose Over -flatten +matte dmap_hlines.png 

#!/usr/bin/bash

  convert gradient.png dmap_hlines.png \
          -virtual-pixel tile  -fx 'u>=v'   dgrad_dmap_hlines.gif 

#!/usr/bin/bash

  magick convert gradient.png dmap_hlines.png `
          -virtual-pixel tile  -fx 'u>=v'   dgrad_dmap_hlines.gif 

  convert dmap_hlines.png pgm:- | pnmdepth 9 | pnmnoraw > dmap_hlines.pgm 

P2
12 4
9
7 8 8 8 8 7 6 6 5 5 5 6 
2 1 1 1 1 2 3 4 4 4 3 3 
6 6 5 5 5 6 7 8 8 8 8 7 
3 4 4 4 3 3 2 1 1 1 1 2 

  <threshold map="hlines12x4" alias="hlines">
    <description>Horizontal Lines 12x4</description>
      <levels width="12" height="4" divisor="9">
        7 8 8 8 8 7 6 6 5 5 5 6
        2 1 1 1 1 2 3 4 4 4 3 3
        6 6 5 5 5 6 7 8 8 8 8 7
        3 4 4 4 3 3 2 1 1 1 1 2
      </levels>
  </threshold> 

#!/usr/bin/bash

  convert shadow.png  -channel A  -ordered-dither hlines   shadow_hlines.gif 

#!/usr/bin/bash

magick convert shadow.png  -channel A -ordered-dither hlines  shadow_hlines.gif 

#!/usr/bin/bash

  montage dpat_symbols.gif   -geometry +5+0 \
          -tile x1 -background none -mattecolor blue  -frame 3 \
          dpat_syms_images.gif
  convert eyes.gif -alpha off -colorspace sRGB -grayscale Average \
          +matte -scale 1600% -negate  \
          dpat_symbols.gif -virtual-pixel tile -fx 'u[floor(15.9999*u)+1]' \
          eyes_syms.gif 

#!/usr/bin/bash

  magick montage dpat_symbols.gif   -geometry +5+0 `
          -tile x1 -background none -mattecolor blue  -frame 3 `
          dpat_syms_images.gif
  magick convert eyes.gif -alpha off -colorspace sRGB -grayscale Average `
          +matte -scale 1600% -negate  `
          dpat_symbols.gif -virtual-pixel tile -fx 'u[floor(15.9999*u)+1]' `
          eyes_syms.gif 

#!/usr/bin/bash

  magick montage dpat_map.gif   -geometry +5+0 -tile x1  -background none  `
          dpat_map_images.gif
  magick convert -seed 100 `
          -size 200x200 plasma:'gray(50%)-gray(50%)' -blur 0x15 `
          -channel G -auto-level +channel -set colorspace sRGB `
          dpat_map.gif -virtual-pixel tile  -fx 'u[floor(5.999*u.g)+1]' `
          map.gif 

#!/usr/bin/bash

  magick montage dpat_map.gif   -geometry +5+0 -tile x1  -background none  `
          dpat_map_images.gif
  magick convert -seed 100 `
          -size 200x200 plasma:'gray(50%)-gray(50%)' -blur 0x15 `
          -channel G -auto-level +channel -set colorspace sRGB `
          dpat_map.gif -virtual-pixel tile  -fx 'u[floor(5.999*u.g)+1]' `
          map.gif