Reducing .pdf size
December 19, 2012 8:51 AM   Subscribe

Is there a failsafe way to make a pdf smaller?

Ok, I have these tools! A macbook, the internet, Preview. There are some online sites for doing this for free, but I've noticed that it's a one-shot thing. If the pdf is still too big, there's no way to go in and make it smaller than the one-reduced file.
There are also a lot of instructions online, including here, but some of the methods seem to refer to programs or versions of programs that are not on my computer (Adobe, etc.). Or it might reduce in Quartz but still be too big, and then won't reduce again. Is there a failsafe way to do this, when a deadline is coming up and the pdf just needs to get small enough to send? Creative ways are fine.

Thanks for any tips!
posted by kettleoffish to Technology (8 answers total) 4 users marked this as a favorite
Open the PDF in Preview.

From the File menu choose "Export..."

In the Export dialog, use the Quartz Filter "Reduce File Size"

This is not failsafe. It usually makes things smaller without reducing the document quality, but sometimes it messes things up terribly. So YMMV. But it's a good first step.
posted by alms at 8:55 AM on December 19, 2012 [1 favorite]

If it is a text-heavy pdf, I use Preview. Open the pdf in Preview->Save as->choose "reduce file size".
posted by bwonder2 at 8:58 AM on December 19, 2012 [1 favorite]

It really depends on what is inside the PDF. PDF is basically a container format that can contain lots of other stuff: TIFF or JPEG images, EPS vector images, and of course PostScript-ish text.

There are lots of ways to make them smaller, depending on the exact type of content. If they are images, then you need to throw away data or compress it more (or both). If it's text, then you can use various tricks to eliminate unnecessary information (e.g. embedded fonts), or at least eliminate redundancies and clean up the markup. But that's pretty tricky to do well.

Acrobat Distiller is probably the best tool for the job but it's expensive. And it's expensive because it does some pretty tricky stuff under the hood, and gives you fine-grained control over it.

The Quartz "Reduce File Size" option is the more idiot-proof, free way ... but as alms says, sometimes it works fine and sometimes it fails horribly. And there's not really any control over what it does: I presume it goes through a few standard methods of reducing images via compression and tries to remove obviously redundant PostScript data, but you don't have much control over it. I'm pretty sure that the Preview option to reduce file size just runs it through the same Quartz filter.

If that doesn't reduce the file size enough, my only suggestions are to go into the application that you're using to generate the PDF in the first place, and try to reduce the sizes of any embedded files (particularly reducing bit depth; B&W images should be 1 bit if possible, not greyscale, etc.). If that doesn't help and you have a hard file-size limit, you might need to break the output into several separate files. Not ideal, but it's not exactly uncommon either.
posted by Kadin2048 at 9:04 AM on December 19, 2012 [1 favorite]

For the sake of completeness, if you can find an old copy of Acrobat Pro -- mine is from 2009, and it still works just fine -- "Adobe PDF Files, optimized" is one of the "Save As" format/file type choices. Choose File menu > Save As and then in the Format pulldown, choose "Adobe PDF Files, optimized". It can reduce a file by 20% to 80%+, depending on file content. Sorry if this is too old school or expensive, but it is a very simple solution that works 100% of the time.
posted by mosk at 9:06 AM on December 19, 2012 [1 favorite]

Have you tried simply zipping it up? Depending on what the PDF contains, you may not be able to generate a smaller file. You may want to play with the complexity or embedded images and see if you can reduce the size.

Also there are several online PDF optimizers. Found this off a quick google search.
posted by wongcorgi at 9:20 AM on December 19, 2012 [1 favorite]

You can do this in Preview. The standard "Reduce" option can be modified. It sounds scary, but if you follow the instructions you can create your own compression filters. Basically, you copy the standard "reduce file size" Quartz filter in the ColorSync utility. For this copy, you can specify the specific compression parameters (e.g. downsample all JPGs to 150dpi). Your new filter will show up in the menu of "Quartz Filter" when you choose "Save as..." in Preview.
posted by swordfishtrombones at 10:09 AM on December 19, 2012 [2 favorites]

No failsafe ways, I think. But what's producing the large PDF in the first place?

The simplest space saving measure is to convert embedded images to jpegs (instead of tiff or - horror - bitmaps), and that's mostly what Preview or the Quartz filters above (clever! didn't know I could add to my menu choices) will do.

But you need to be careful about the output quality - if the PDF is going to be uploaded to a review panel ("send", "deadline") somewhere, for example, I would not reduce quality on the whole file. I'd attack the component images individually, make sure they were still good enough, then put the whole thing together.
posted by RedOrGreen at 1:29 PM on December 19, 2012 [1 favorite]

Many thanks all!!!!!

Another thing that worked pretty darn well:

Save the .pdf as a .jpg (with reduced resolution, this is the important thing, if there's no menu for that it doesn't work), then save it as a .pdf again.
posted by kettleoffish at 8:17 AM on December 23, 2012

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