Legacy ImageMagick Discussions Archive

I'm certain it is, because I've done it from 16-bit greyscale to 8-bit greyscale here:-
http://www.imagemagick.org/discourse-se ... 5dc9c07e6f

Code: Select all

magick image24.png -depth 16 -define png:format=png48 -define png:compression-level=1 -define png:compression-filter=1 -define png:compression-strategy=2 png48:image48.png
magick image48.png -depth 16 -define png:format=png48 -define png:compression-level=1 -define png:compression-filter=1 -define png:compression-strategy=2 -blur 2x6 -blur 3x9 -depth 16 png48:image48b.png
magick image48b.png -depth 16 -define png:format=png48 -define png:compression-level=1 -define png:compression-filter=1 -define png:compression-strategy=2 -motion-blur 99x99+0 -depth 16 png48:image48b_.png
magick image48b_.png -depth 8 -define png:format=png48 -define png:compression-level=1 -define png:compression-filter=1 -define png:compression-strategy=2 -dither Riemersma -colors 16777215 png24:image48z.png

(using "Version: ImageMagick 7.0.7-28 Q16 x64 2018-03-25")

Any help with this BAT file would be appreciated. Either it just doesn't work, or I'm doing something obviously stupid?

Well, I've concluded that it doesn't work!
However, the obvious solution to this is to split the colour channels and do the dithering separately, then combine again:-

Code: Select all

magick image24.png -resize 4096x2048 -define png:format=png48 png48:image48.png
magick image48.png -blur 3x9 -depth 16 -define png:format=png48 png48:image48b.png
magick image48b.png -motion-blur 33x33+90 -depth 16 -define png:format=png48 png48:image48c.png

magick image48c.png -channel R -separate -depth 16 -define png:format=png48 png48:image48c_red.png
magick image48c.png -channel G -separate -depth 16 -define png:format=png48 png48:image48c_grn.png
magick image48c.png -channel B -separate -depth 16 -define png:format=png48 png48:image48c_blu.png

magick image48c_red.png -dither riemersma -colors 255 image48c_red2.png
magick image48c_grn.png -dither riemersma -colors 255 image48c_grn2.png
magick image48c_blu.png -dither riemersma -colors 255 image48c_blu2.png

magick image48c_red2.png -resize 2048x1024 -define png:format=png24 png24:image48c_red3.png
magick image48c_grn2.png -resize 2048x1024 -define png:format=png24 png24:image48c_grn3.png
magick image48c_blu2.png -resize 2048x1024 -define png:format=png24 png24:image48c_blu3.png

magick image48c_red3.png image48c_grn3.png image48c_blu3.png -combine -set colorspace sRGB -define png:format=png24 png24:image48d!!!.png

This gives me the result I was looking for.

http://www.violae.net/temp/48to24dither.jpg

Legacy ImageMagick Discussions Archive

[solved] Dithering from 48bit (to 24bit) image not possible?

[solved] Dithering from 48bit (to 24bit) image not possible?

Re: Dithering from 48bit (to 24bit) image not possible?