TIP: PDF reduction keeping it readable
  • Hi Acorn Community,

    (any related tips you have, I"d appreciate on this discussion!)... /Fred Johnston

    I just thought I'd throw this tip up, as I was having a horrible time trying to find a balance between my PDF being readable and being able to put it into Evernote.

    I had a bunch of screenshots (MAC) that i put onto an 8.5x11 canvas.

    When i created it at 300dpi and exported, it was 3.6MB, BUT UNREADABLE it was so freakin blurry it was UNUSABLE.
    When i created it at 600dpi it was READABLE, so freakin big (39.4MB) that it was unusable as an Evernote attachment (and moving around it in Preview was SLOW, DOGGY!)

    So then I exported the 600dpi PDF (that exported out of Acorn) from Preview, at 75%, and it took it from 39.4MB down to 1MB (UNBELIEVABLE!) AND IT IS TOTALLY READABLE!

    I hope in future, that Acorn people can work on getting a better PDF creator, as this one sucks.
    (and maybe just picking 75% as an export option, and getting it WAY down to a USABLE size)

    Here's the steps I used to set up various PDF export options.... 25%, 50% and 75%... of which 75% works great...
    (I found this helpful link at...

    Savvy Preview users know they can do some interesting things to PDFs—convert them to black-and-white or sepia tone, increase or decrease their lightness, and more—by selecting File -> Export, then selecting one of the Quartz filters in the resulting dialog box. Reader zpjet is one of those users, but he was never satisfied with results of the Reduce File Size filter (which he'd use when trying to make PDFs small enough to send by e-mail): It made them too small and made the graphics fuzzy.
    After a little digging around, he found that these filters are located in the folder /System/Library/Filters, and that they're XML files that are easily edited with TextEdit (or any other text editor). Examining the file for the Reduce File Size filter, he found out why it didn't work for him: Two of the parameters—Compression Quality and ImageSizeMax—were just too low (0.0 and 512, respectively).
    So he copied this file to his Desktop, made two copies of it, and then renamed all three: Reduce File Size Good, Reduce File Size Better, and Reduce File Size Best. Then he changed the parameters of each file: 0.25, 0.5 and 0.75 for Compression Quality (respectively) and 842, 1684, and 3508 for ImageSizeMax (ditto). (The first is A4-size at 72dpi, the second A4 at 144dpi, and the third A4 at 300dpi).
    Finally, he changed the default string for the Name key at the end of each file—which is what displays in the Export menu—to match its file name. He then created a /Library/Filters folder and put all three edited files in it.
    Now, when he opens a picture or PDF in Preview, he has the option of four Reduce File Size filters. So, for example, let's say he's starting with a JPEG of a scanned A4 invoice at 300dpi, and that file is 1.6MB in size. When he exports that to PDF format with the standard Reduce File Size filter, the file goes down to 27KB, but it's quite unusable—fuzzy and hard to read. Using the Good filter produces a file that is much easier to read and only slightly fuzzy, and it weighs in at 80KB. A file produced with the Better filter comes out at 420KB and clear; Best is 600KB and almost as good as the original.

  • The reason why Acorn's PDFs are so big is because we use lossless compression when exporting. If you want print production quality, you want lossless.

    When you export the PDF from Preview with compression, it's most likely using JPEG for its image format, which will make the image smaller but it comes with a loss of quality (by throwing pixels out).

    We'll consider adding lossy compression options for a future release.

    Thanks for the feedback!


  • That would be great, Gus, thanks.

    Respectfully, i ask...
    So why does 300dpi lossless end up being much worse and 3x larger than 600dpi at 75%?
    (you're the pro for sure, just wondering why)

    So, this may still be a VERY handy tip for those wanting a very good AND small PDF resultant file.

  • I'd have to see the files in question to be able to answer correctly. It all depends :)

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