Use case: You are using (La)Tex to create your document and include some big non-vector graphics or high-quality scanned documents via \includepdf{} from pdfpages package. You could resize/size-optimize your included parts one by one to make your resulting PDF document smaller. Or you could compile your document and then use a trick to reduce the size of the final compiled document as PDF at once:
pdf2ps finaldoc.pdf finaldoc.ps && ps2pdf finaldoc.ps finaldoc_reduced.pdf
That way I managed to reduce the document size from 22MB to 4MB. Of course, the effect depends on the material included in your document. Give it a shot.
Update (2012/01/20):
If the hint above is still not enough you might want to try to reduce the final size with gs via PDFSETTINGS option described in the Ghostscript Documentation:
-dPDFSETTINGS=configuration
Presets the "distiller parameters" to one of four predefined settings:
/screen selects low-resolution output similar to the Acrobat Distiller
"Screen Optimized" setting.
/ebook selects medium-resolution output similar to the Acrobat Distiller
"eBook" setting.
/printer selects output similar to the Acrobat Distiller
"Print Optimized" setting.
/prepress selects output similar to Acrobat Distiller
"Prepress Optimized" setting.
/default selects output intended to be useful across a wide variety of
uses, possibly at the expense of a larger output file.
You can apply the desired parameter using ps2pdf:
ps2pdf -dPDFSETTINGS=/screen finaldoc.ps finaldoc_reduced.pdf
or gs:
gs -q -dBATCH -dNOPAUSE -sDEVICE=pdfwrite \
-dPDFSETTING=/screen -sOutputFile=finaldoc_reduced.pdf finaledoc.ps
Since it will lower the quality of the document it is advisable to check whether the document will still meet the requirements for the usage intended.
