Question on file compression. about pikepdf HOT 1 CLOSED

pikepdf enables all of the safe, lossless compression options. You may need to save with recompress_flate=True or else compression of existing compressed streams is not attempted (although, savings may be minimal). To achieve anything better and truly aggressive you need to do something that involves lossy/destructive operations that involve reinterpreting the PDF or studying its contents to see what elements can be removed.

Your first file is ~10 MB, almost all of which is due to the background on pages 1, 7, and 19.

qpdf has a command line utility to JPEG-compress images in the PDF. (There's a way to access this through pikepdf.Job as well, although documentation is admittedly sparse on it, so qpdf is easier to use at this point.) That would work, and given the type of images, JPEG should be fine.

from pikepdf.