On Monday 19 March 2007 17:20, Stefan Monnier wrote: > > What xsane version did you use? > > It was 0.991. > > > Please test xsane-0.994 and please test with and without zlib compression > > for PDF (Preferences/setup/filetype) > > I've just tried it with zlib compressed (I always use this option) and the > problem is indeed fixed, so the PDF generated is now viewable with > macosx's preview. > > While testing it I noticed that for the picture I tried (a scan of > a mostly blank letter-size yellow sheet in 150dpi and greyscale) I get the > following file sizes in bytes: > > 0.991: 1551241 > 0.994: 1211006 > 0.991 through pdf2ps|ps2pdf: 127159 > 0.994 through pdf2ps|ps2pdf: 127163 > > So the 0.994 version also generates smaller files (at least for this one > test). Oddly enough pdf2ps|ps2pdf generates much smaller files still (my > experience has indeed been that it generates smaller files, but usually > just by maybe 10-20%, kind of like what we see between the 0.991 and 0.994 > files, so it seems this here test is not representative of my more usual > scans ;-)
xsane-0.994 uses 8 bit encoding while older versions used a special 7 bit encoding that has to be used for several posctscript printers. This is the reason why xsane-0.994 produces smaller pdf files. when you do pdf2ps | ps2pdf then there is possibly a resampling of the image data so that you get a lower resolution than you used while scanning the image. It also is possible that you get jpeg coded images this way, xsane stores the images in a lossless way. Best regards Oliver
