But I digress.
This info is a lot of places on the net already, but I want to add it here for my own reference as I've forgotten the simple command line a few times already and had to re-search it.
In short, use ghostscript:
gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdfThe PDFSETTINGS presets equate to the following resolutions:
- /screen ... screen-view-only quality, 72 dpi images
- /ebook ... low quality, 150 dpi images
- /printer ... high quality, 300 dpi images
- /prepress ... high quality, color preserving, 300 dpi images
- /default ... similar to /screen
Other suggested command line arguments made various places:
- -dColorImageResolution=38 -dColorImageDownsampleType=/Average -dGrayImageDownsampleType=/Average -dGrayImageResolution=38 -dMonoImageResolution=38 -dMonoImageDownsampleType=/Average -dOptimize=true -dDownsampleColorImages=true -dDownsampleGrayImages=true -dDownsampleMonoImages=true -dUseCIEColor -dColorConversionStrategy=/sRGB
This page is quite good for further tips (such as recompressing with lossless compression).