Hmmm, I guess I learn something new every day. I wouldn't have suspected that ghostscript writer could concatenate pdf's and save so much during compression.
So I just did a test, scanning some tax forms in 8-bit grayscale to z[0001 --- 0019].pdf using xsane and then combining using both gs and pdftk. The results: $ du -csh z00??.pdf 388K z0001.pdf 1.2M z0002.pdf 1.3M z0003.pdf 1.1M z0004.pdf 1.6M z0005.pdf 892K z0006.pdf 724K z0007.pdf 908K z0008.pdf 1.3M z0009.pdf 728K z0010.pdf 556K z0011.pdf 196K z0012.pdf 1.4M z0013.pdf 196K z0014.pdf 580K z0015.pdf 472K z0016.pdf 376K z0017.pdf 920K z0018.pdf 1.3M z0019.pdf 16M total # Now concatenate using pdftk $ pdftk z00??.pdf cat output PDFTK.pdf $ ls -sh PDFTK.pdf 16M PDFTK.pdf # Concatenate using ghostscript's re-write $ gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=GS.pdf z00??.pdf $ ls -sh GS.pdf 8.5M GS.pdf Of course, pdftk allows mixing papersizes. Ghostscript's writer will truncate pages which are larger then the default or specified pagesize. Not sure if ghostscript can write pdfs with mixed papersizes. For good measure, I also tried pdfjam/pdfjoin/pdflatex and it too just concatenates the pdfs into a 16M file.
