How to reduce size or compress PDF files?

Hi guys,

Does someone knows if there is a way to reduce the size of the PDF file with good quality even on Pictures and Scanned documents? I know the option 'export', 'quartz filter' 'reduce size', but the compression is so extrem. Many files can't not been read, the quality is so bad. Is there a additional app, software or extension that let the user play with the compression on pdf files and let it be more personalized like the dopdf V7 available for windows? i am very dissapointed with this. Please help or suggestion. I will appreciate it. Thanks