Reducing your PDF file size (on a mac)

The other day I scanned in a large document about 50 pages that needed to be submitted on-line. This was an application for my Coast Guard Masters license. They had very specific requirements that it be a single PDF, and less than 10Mb. It also had to be readable! The initial scan ended up being approximately 26mb, at 300 dpi. This was certainly not going to work, and I didn’t feel like scanning 50 pages at 150 to see how it looked. So the hunt began.

One of the beauties of a Mac is that PDF files are native to the system, you don’t need acrobat reader, or pro, it’s just there. From any print dialog you will find a PDF option you can select and save any document as a PDF, but on to how to reduce the size.

Step 1: Open the PDF in preview
Step 2: File Save As
Step 3: At the bottom of the save as dialog you will see Format PDF, and Quartz Filter, choose Reduce File Size
-voila- thats it… except this is a very low quality filter, my first attempts took the 26mb filter and made it 1.6mb. It was there but text was almost unreadable. Now at this point most of us would say well I guess I can’t do it. Hey, this is a Mac we are talking about, remember, native PDF support? The key is the Quartz Filter, the mac has the ability to create additional filters for manipulating images, remember how the art department and the designers always had Mac’s before anyone else.. well here is why.

Under Applications, Utilities you will find one called ColorSync, you can also located it with the spot finder in the upper right. Once you start it it may want to verify your profile, you can let it or say repair. Once it’s open click on the filters option. You will see the reduce file size filter, if you click on the down arrow on the right you can choose duplicate filter.

Once the filter is duplicated, you can rename it as you see fit. But lets go edit this filter and improve our image quality. If you open up the filter you will notice two filter options, Image Sampling, and Image Quality. The image below shows the settings I thought worked best, it resulted in about 1/2 the file size.

It took a while to tune the settings, many suggested max quality under image compression, but the actual improvement happened when I changed the sampling. The default is 50% of scale, which I put at 100%, the real difference happened by changing the Max & Min pixels. By setting Max at 1026, and Min at 512 I ended up with half the file size of a 300dpi pdf.

Hopefully this will help you when emailing PDF’s and tell you more about the Mac.