If you simply re-save a PDF, without this option, no compression occurs.) However, this option uses compression, so it reduces the quality of images and text in the resulting PDF. (Note that Preview Save dialog includes, in the Quartz Filter pop-up menu, a Reduce File Size option.
You just open a PDF in Preview and then save it (as a PDF) again the resulting file will usually be significantly smaller than the original with no difference in quality.
But many people don’t realize that Mac OS X’s own Preview application can reduce the size of PDF files without any additional software-and without actually performing any compression. There are a number of Mac utilities that will compress PDF files for easier e-mail sending, or, for developers, to reduce the size of an application bundle that includes lots of PDFs PDFshrink and PdfCompress are just a couple examples.
