Code:
for file in bg_*.png ; do ; convert ${file} -filter LanczosSharp -resize 758x1024 -background black -gravity center -extent 758x1024 -colorspace Gray -dither FloydSteinberg -remap ~SVN/Configs/trunk/Kindle/Touch_Hacks/ScreenSavers/src/linkss/etc/kindle_colors.gif -quality 75 -define png:color-type=0 -define png:bit-depth=8 _${file} ; done