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How Do I Reduce the File Size Of a PDF On macOS?

I have a PDF file that’s 600+ MB in size. I opened it in Preview, selected “Export” from the File menu. In the window that opened, I selected “PDF” as the Format, and from the Quartz Filter menu I selected “Reduce File Size 75%,” (an option I think I may have added using Color Sync Utility several years ago). The resulting exported file was actually larger in file size than the original PDF document. I’ve tried “Export to PDF,” and I’ve tried exporting it from “Print” as well. While there is some variation, still all exported PDFs are larger than 600 MB.
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Cameron

Comments: 3 Responses to “How Do I Reduce the File Size Of a PDF On macOS?”

    5 months ago

    The Quartz Filter method will reduce the size and quality of images in the document. However, if the images have already been optimized, you won’t see a difference or it could get a little larger as in your case.

    It sounds like the PDF you have is just a large one that is already optimized. Without other information, it is hard to make suggestions. What is it and how many pages is it? 600MB may just be the best size for it. But if it contains a lot of images you don’t care about then maybe you can open it up in Preview and remove some full-page images?

    Cameron
    5 months ago

    It’s Part 3 of a 4-volume book set that I was contracted to proofread. For context:

    Volume 1 is 8.4 MB (940 pages)
    Volume 2 is 5.1 MB (1,089 pages)
    Volume 3 is 663.6 MB (737 pages)
    Volume 4 is 4.9 MB (366 pages)

    They are all in similar style. Other than book cover art, Volume 4 is the only one with images (black & white), with the exception of some small graphics of the Hebrew alphabet at the beginning of Volumes 1&2.
    The cover art for Vol. 3 is 4KB (others are several hundred KB).

    5 months ago

    Cameron: Well, there is clearly something, probably an image, in volume 3. Do a binary search to find it: copy the first half into a new document and export. Same for second half. Is one small and one large? Do the same with the large half. Keep cutting in half until you locate the bad item(s). Binary search should get you there fast.
    Maybe this is because this PDF is scanned images of text, instead of text?

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