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macrumors 68020
Original poster
Oct 21, 2005
One thing I love about OSX is that you can "Print" PDFs from web pages or just about anything else. I use that feature all the time and I've even created a keyboard shortcut ("Keyboard" system preference) for it so I can just press CMD-P twice (which brings up the print menu, then "Save to PDF"):

But I digress...
Here's my problem: I've scanned several documents and want to join them together and create a single PDF file (with the first image file open in Preview, select "View"-"Thumbnails", drag the rest of the scanned image files over, organize them in the right order if necessary (drag them around, before/after the other images), then finally create the PDF by selecting all of the images (click on one of the thumbnails, then press CMD-A which should highlight them all) then go to the "Edit" menu -"Print" (which brings up the print window), then click on the PDF button on the left bottom side and further click on "Save as PDF..." (or simply press CMD-P again if you've set up a shortcut as I've shown above) which will save all the scanned documents into a single PDF file.

My question is this: How do I make the best possible quality out of the PDF, taking advantage of the scanned resolution I've used?
For instance, some documents I've scanned recently for this purpose are all scanned in 2408x3436 pixels at 300 pixels/inch and saved as JPG files. Now, the print dialog has options for creating your own custom print sizes, but they're not in pixels but mm (or inches I suppose).
Another thing is that I don't want to make the PDFs unnecessarily large, so assuming I want to create a PDF with the above image files at a printable resolution (which is why I scanned them at 300 DPI in the first place), and secondly: if I want to create a PDF file with the same scanned images but just for viewing on screen (Mac, iPad, phone etc.) -which sizes should I choose for custom print sizes?


macrumors 6502a
Jan 11, 2017
I'm not sure you have a lot of choices: I haven't seen them anyway.
But there are a couple of things that might help what you are trying to do:
In Preview >preferences, you've got the option to have 1 screen point equal I pixel and I think that will give you maximum quality.
Also in Preview, if you choose "Export' rather than 'Export as pdf' you get a dialogue where you can choose the file format (ok so you choose pdf) but then underneath you'll see 'Quartz filter' and in Quartz filter you can choose 'Reduce file size' and that will give you the smallest size you can get.
Ì think that's about it.
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Reactions: HDFan


Staff member
Jul 1, 2014
I believe you can tweek the Quartz Filters via ColorSync program (Applications/Utilities/

Have not done that myself, so not sure how much you can tune with that.
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