Can I programatically change the quality of a PDF?
I have a client that is a newspaper, and when they submit the PDF form of the paper to their site they are submitting the same copy they send to the printer which can range from 30-50Mb. I can manually lower the quality (still plenty high for the web) and it will be 3-5Mb so this will help my hosting substantially.
You should check TCPDF library or php documentation. I never worked with pdfs in php, but I think you can do that you need with TCPDF easily. If your pdf is composed by images, check this example, maybe help you.
Regards
Zend_Pdf is the best Free library for reading and manipulating existing PDFs, but it does not go nearly deep enough to do what you need. I do not believe there is a PHP library for manipulating PDF files at that level (that is, being able to extract embedded images and replace them with lower quality versions).
That seems like something that would require nothing short of the Adobe PDF SDK / libraries. I have worked with them quite bit, but I have never attempted to change the resolution of an existing PDF. The libraries are pricey so it's likely that is not an option for you.
I want to say that Perl's PDF::API2 has an optimize script bundled with it, but I have never used that functionality. It may be worth a look. The module itself is pretty thorough. Although, a PDF that large not be that fastest to process with it.