In terms of compression for scanned notes, I haven't found anything that comes close to what even an older version of Adobe Acrobat yields, due to the use of the JBIG2 codec. Has anybody found any way to compress PDF files with JBIG2 on Linux/Mac? It's pretty much the only reason I have to find a Windows machine with Acrobat installed a couple of times a year, to postprocess a batch of scanned PDFs.