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NiLuJe · 11-27-2013, 10:45 AM

@Akirainblack: It matters (in some circumstances) for the K2/3/4 version of the hack, so for the sake of simplicity, and because it's a good habit to take, I unified the FAQ on that point

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The *other* difference is, of course, quality: if you feed the Kindle a full-color image (or a full 8-bit grayscale image for that matter), the dithering will be done by the hardware, and it's a crappy, crappy dithering (fast, but crappy) compared to what any good decent image processing software will do.

@chipf0rk: Yup, ImageMagick would be good, that's what the cover mode uses

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You'll need the colormap, which you can rip from the hack (linkss/etc/kindle_colors.gif).

Scaling+Dithering:

Code:

convert in.jpg -filter LanczosSharp -resize 758x1024 -background black -gravity center -extent 758x1024 -colorspace Gray -dither FloydSteinberg -remap kindle_colors.gif -define png:bit-depth=8 -quality 75 out.png

And in case it isn't clear, the scaling part:

Code:

-filter LanczosSharp -resize 758x1024 -background black -gravity center -extent 758x1024

And the dithering part:

Code:

-colorspace Gray -dither FloydSteinberg -remap kindle_colors.gif -define png:bit-depth=8

Script that to loop around whatever your want in your favorite scripting language, and boom.

11-27-2013, 10:45 AM	#837
NiLuJe BLAM! Posts: 13,506 Karma: 26047202 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	@Akirainblack: It matters (in some circumstances) for the K2/3/4 version of the hack, so for the sake of simplicity, and because it's a good habit to take, I unified the FAQ on that point . The other difference is, of course, quality: if you feed the Kindle a full-color image (or a full 8-bit grayscale image for that matter), the dithering will be done by the hardware, and it's a crappy, crappy dithering (fast, but crappy) compared to what any good decent image processing software will do. @chipf0rk: Yup, ImageMagick would be good, that's what the cover mode uses . You'll need the colormap, which you can rip from the hack (linkss/etc/kindle_colors.gif). Scaling+Dithering: Code: convert in.jpg -filter LanczosSharp -resize 758x1024 -background black -gravity center -extent 758x1024 -colorspace Gray -dither FloydSteinberg -remap kindle_colors.gif -define png:bit-depth=8 -quality 75 out.png And in case it isn't clear, the scaling part: Code: -filter LanczosSharp -resize 758x1024 -background black -gravity center -extent 758x1024 And the dithering part: Code: -colorspace Gray -dither FloydSteinberg -remap kindle_colors.gif -define png:bit-depth=8 Script that to loop around whatever your want in your favorite scripting language, and boom.