gs -dNOPAUSE  -dBATCH \
	-sDEVICE=pdfwrite -dCompatibilityLevel=1.4 \
	-dDetectDuplicateImages=true \
	-dDownsampleColorImages=true \
	-dDownsampleGrayImages=true \
	-dDownsampleMonoImages=true \
	-dColorImageResolution=150 \
	-dGrayImageResolution=150 \
	-dMonoImageResolution=150 \
	-dEmbedAllFonts=false \
	-dSubsetFonts=true \
	-dConvertCMYKImagesToRGB=true \
	-dCompressFonts=true \
	-dPDFSETTINGS=/screen -sOutputFile=$1.opt.pdf $1


#-dPDFSETTINGS=/screen   (screen-view-only quality, 72 dpi images)
#-dPDFSETTINGS=/ebook    (low quality, 150 dpi images)
#-dPDFSETTINGS=/printer  (high quality, 300 dpi images)
#-dPDFSETTINGS=/prepress (high quality, color preserving, 300 dpi imgs)
#-dPDFSETTINGS=/default  (almost identical to /screen)