Luiz Augusto wrote:
Someone asked it on en.wikisource and I've replied with this: http://en.wikisource.org/w/index.php?title=Wikisource:Scriptorium&diff=p...
DjVu (or at least all conversion tools/configuration options that I've tried in the past months, including the LizardTech Document Express Enterprise pdf2djvu and png2djvu options) is a lossy format. If I convert a .pdf downloaded from Google Book Search I will get a low quality file (70 dpi or 150 dpi per page), but if I extract the images from the same .pdf file using Adobe Acrobat Pro 8 I will get a 600 dpi jpeg for each page (OCR softwares normally recommeds to use 300 dpi images).
Hmm... well, that sucks. :( DjVu is indeed a lossy format, but there's lossy and then there's lossy. Minor loss of fidelity in the reproduction of the paper grain at 600 dpi would be perfectly reasonable -- but turning a 600 dpi scan into 150 dpi certainly isn't.
Unfortunately, I'm not familiar enough with the DjVu format to suggest any solutions. I'd assume the format must have support for higher resolutions, even if most conversion software might not readily support it, but never having actually used any such software I can't really say.