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Old 01-12-2011, 06:38 AM   #7
kacir
Wizard
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Posts: 3,463
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Join Date: May 2006
Device: PocketBook 360, before it was Sony Reader, cassiopeia A-20
Quote:
Originally Posted by wongdong View Post
There is a better way. If you use a freeware picture viewer like irfanview or xnView,
Well, imagemagick is pretty powerful tool.
Have a look at my post here
https://www.mobileread.com/forums/sho...3&postcount=12
It can do very nice dithering
convert escher01.png -quantize GRAY +dither -colors 16 -rotate "-90>" escher01.bmp

If you want exactly four colors, you can use
convert escher01.png -quantize GRAY +dither -colors 4 -rotate "-90>" escher01.bmp
The above command works with 800x600 or 600x800 pixel bitmap, for explanation go to my post mentioned above. It is better to resize/crop each image manually using good interactive program, like Gimp, so you can see exactly where you are cutting or adding to picture.

Last edited by kacir; 01-12-2011 at 06:55 AM.
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