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Thread: How to Rotate PDF but keep original DPI without changing settings for every file?

  1. #1

    Default How to Rotate PDF but keep original DPI without changing settings for every file?

    I scanned a heap of documents to PDF format (I now realise if id originaly scanned to JPG I never would have encountered any problems, but anyway.... ).

    I was using irfanview to quickly rotate and/or crop then save as. I found that because Ifranview will scroll through a directory I could get through a lot of documents very quickly.

    I have now discovered that all those modified PDF files look terrible because they are now 96dpi instead of the original 200/300dpi (I originally thought they were bad because of wrong printer scan DPI settings).

    Even though the PDF save as side box settings says it is lossless, it actually saves to the viewing DPI in the settings. Say a PDF is 300dpi and I want to rotate or crop, then I have to change the dpi settings to the same quality in Irfranview. Quality is good, but file size is now double the original. Plus doing it this way means I first need to check the dpi of the file to be changed then match it in Irfranview, then repeat for every file. This means that there is no point using Irfanview any more because that way is slow and increases file sizes.

    I really liked being able to scroll through a directory of many files and crop/rotate the files that need it.

    Is this just the way it is? So I should make sure printer scans to jpg or use acrobat for PDF (can acrobat scroll through a directory like Irfan?)

    Or is something wrong with my installation/settings so I can continue to use irfanview for pdf files without losing a ton of quality ? (I tried both pdf.dll and ghostscript)

    Last edited by Bhikkhu Pesala; 30.11.2016 at 10:12 AM.

  2. #2
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    The DPI for PDF files is set in Settings, Plugins, PDF Plugin Options.

    Setting that to 300 dpi will solve the resolution problem, but it will also make loading significantly slower.

    Try PDF-XChange Editor for working with PDF files. Many of its features, including rotation of pages, are free, but you may need to register if you want more options for editing PDF files
    Last edited by Bhikkhu Pesala; 30.11.2016 at 10:18 AM.

  3. #3
    Hobby User Sprintdriver's Avatar
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    Default pdfsam

    pdfsam would be my choice for multi page rotation. It also merge and extracts pdf files, which is a very useful feature.

    Link to homepage:
    Last edited by Sprintdriver; 30.11.2016 at 10:28 PM. Reason: include link to page
    If it hurts not to drint, don't waste the bottle then.

  4. #4


    Thanks for the suggestions. I had a look. But for now i think ill make sure my files are saved as JPEGs and then use acrobat to convert.

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