example
reduce
using gs
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/prepress -dNOPAUSE -dQUIET -dBATCH -sOutputFile=<DESTINATION>.pdf <ORIGINAL>.pdf
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=<DESTINATION>.pdf <ORIGINAL>.pdf
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=<DESTINATION>.pdf <ORIGINAL>.pdfprepressHigher quality output (300 dpi) but bigger sizeebookMedium quality output (150 dpi) with moderate output file sizewebLower quality output (72 dpi) but smallest possible output file size