Hallelujah! OS X Can Reduce PDF File Size! – Stephen Foskett, Pack Rat

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Hallelujah! OS X Can Reduce PDF File Size!

Posted on Oct 23, 2008 by Stephen

One feature of OS X that really surprised me was it’s amazing ability to handle PDF files. Since switching to mac earlier this year, I’ve become a PDF monster – OS X allowed me to go completely paperless for most business functions, including expense reports. I’ve started using the “Save as PDF” function constantly, organizing receipts and online statements for later reference, which Spotlight makes even easier.

But one thing bugged me. I use an HP Photosmart C6180 all-in-one scanner/printer/fax/copier, and while it works well, its scans are huge. I mean massive. A single-page color PDF scan of a recent magazine article I wrote became a 6.1 MB PDF file!

Then I noticed the “Reduce File Size” Quartz filter in the “Save As” dialog box. “Cool” I thought, “OS X will automatically reduce the file size for me!” Not so fast, though – although this filter did reduce the file size to just 36 KB, it also made the text unreadable! I needed a better solution…

This post is part of my series focused on Apple OS X tips and tricks.

Look what the generic "Reduce File Size" Quartz filter in OS X did to my document - it's unreadable!

Look what the generic “Reduce File Size” Quartz filter in OS X did to my document – it may have reduced the size from 6.1 MB to 36 KB, but it’s unreadable!

So I soldiered on, trying to tweak the scanner’s settings to produce smaller files. But they were still multi-megabyte files. I was stumped.

But the other day, I decided to try again to find a solution. And hallelujah! A solution I have found!

It turns out that you can set up your own custom Quartz filters in OS X – it’s just not obvious how to do it. Buried in the Color Sync utility is a tab called Filters.

Here, I discovered why the default “Reduce” filter looked so bad. My scans were in TIFF format, which looks great but is basically uncompressed. When you apply the “Reduce” filter, it converted any images it found to JPEG format, which dramatically reduced the image size. But it also scaled the images down to a miniscule 512×128 pixels! This is fine for the average inline illustration but terrible for a full-page image like a scanned document!

So, following the directions I found at hoboes.com, I created my own filter. Mine is exactly the same as the generic Reduce filter in that it converts images to medium-compressed JPEG, but I skip the image re-sampling so it keeps its native resolution. The result is a Quartz filter that reduces the size of scanned images but leaves them looking good enough to read or print. See the results below for yourself!

By skipping the image scaling I was able to reduce the 6.1 MB file to 468 KB while maintaining readability

By skipping the image scaling I was able to reduce the 6.1 MB file to 468 KB while maintaining readability

Then I got thinking – what if I turned the JPEG quality down to minimum? The results still looked pretty good – my 6.1 MB file was now 196 KB and looked just about as good as the original for casual viewing.

By turning the JPEG quality to minimum, I reduced the file size to just 196 KB!

By turning the JPEG quality to minimum, I reduced the file size to just 196 KB!

So I’m happy. I can again scan and email smaller files. I just wish Quartz supported an open format like PNG! And I wish the HP printer wouldn’t constantly disappear from both OS X and Vista, but that’s another story for another day.

Update: More info on creating a Quartz filter and formatting documents for the iPhone.

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mkt bra.

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