P.S. For 16-color devices, the dithering won't make a big difference. For the 4-color sony, it does. White backgrounds get a light gray snow and black text gets a dark gray one. The end result is decreased contrast on a device which has poor contrast to begin with. I made a mistake, however. The right tool is NOT pnmquant (which does the whole find-the-best-palette bs). Rather, it is pnmremap which lets you specify a custom palette. The command line for it is 'pnmremap mapfile=palette.pnm -floyd' where palette.pnm is a file that contains:
Code:
P2
4 1
255
0 85 170 255
or
Code:
P2
16 1
255
0 17 34 41 68 85 102 119 136 153 170 187 194 211 238 255
Also, in regards to further tuning, I suggest you tweak your default settings a little. This may vary by device, but on my reader the best edge enhancement seems to be 7 not five, and you may want to change your default dilation factor. In fact, how exactly are you doing it right now? By setting a dpi and then multiplying by page size? That would give very inconsistent results if the size of the page is different from A4 (a good example is if one does manual cropping as one should, but also most pdf books are not a4).