PDFOptim

PDFOptim helps you reduce the size of heavy scanned PDF documents. In this respect, it uses a set of filters that allow optimizing file size without any noticeable quality loss.

Needless to say, lighter PDFs are easier to share and occupy less storage space.

The application has a compact interface responding to its batch processing capabilities. You can start by creating a list of items to process, which you can do by adding files and folders as well as by dragging and dropping the desired elements. It is quite convenient that the tool supports side-by-side comparison between the source and the optimized document. This way, there will be no surprises with the final PDF.

One of the main advantages of the tool is that there are multiple options as to optimizing filters. In this regard, you can use any of the two compression methods available: Quartz and Image filters. Although the default options work fine most of the times, you are allowed to control JPEG compression, image sample resolution, image color mode and graphics optimization. Moreover, you can save your preferences as a preset, which you can reuse in the future.

Once you have tried different options and methods, you can finally save your work. At this point, you have two choices: creating a completely new document or replacing the old file with the new optimized version. However, I would not recommend the second just in case anything goes wrong.

When I tried the tool, it allowed me to reduce PDF file size by up to 10 times. It was particularly efficient with scanned documents containing lots of vector graphics. Conveniently, downsizing did not bring about any noticeable quality loss, for example, in text legibility.

There are a few things that I would like to include in my wish list. In this sense, I would like to be able to process and export just a page range. Likewise, the tool would be more complete if it supported applying OCR to scanned text.

In short, PDFOptim is one of the best choices out there when it comes to reducing PDF size without altering the original quality. The product is available from the Mac App Store at a very reasonable price.