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H
huck999
Participant
December 2, 2011
Question

How to compress a scanned PDF?

  • December 2, 2011
  • 2 replies
  • 191885 views

I am using Acrobat 9 Standard.

I have a 22 page printed text document (no pictures) on letter sized paper.  I had it scanned to PDF.  It is 24 MB.  I have a scan of a similar document that someone else did.  It is 332 KB (roughly 100 times smaller).  Both are perfectly legible.

I have 2 questions:

  1. How can I compress the 24 MB document to make it smaller?
  2. Why did I get such huge differences in file size?  And how can I get smaller file sizes from scans.

In my office I have an HP Officejet Pro.  The HP software scans directly to PDF but the file size is large.

    2 replies

    A
    antonyhill
    Participant
    March 21, 2014

    I notice the same. If I scan directly through the device to USB (it has such option), then document is for some 7 pages of text in 600dpi around 800kb. Scanning from computer results in bigger and uglier images. I guess reason is twofold. First scanning settings.

    Documents from scanner device are much cleaner, I guess there is higher contrast set and perhaps tresholds applied so that text is black and white space on paper is white. Scanning from computer through the same scanner results in subtones in the supposed to be white areas. This makes a big difference IMO for quality of compression later the document is created.

    Another thing is the features of the resulting PDF. See more info here:

    http://blogs.adobe.com/acrolaw/2009/08/reducing-the-file-size-of-scanned-pdfs/

    I guess the scanner (it is actually a MFC device) is using high lossless compression which IMO is perfectly fine for the job. No need for lossless compression for scanned documents.

    MichaelKazlow
    MichaelKazlow
    Legend
    December 2, 2011

    I do not have Acrobat 9 Standard, but I believe you can use the PDF optimizer to shrink the size of the file. The best way to control the size of the file is at scanning time. You can usually control the dpi (dots per inch). Most scanners try to scan at the highest resolution, usually 200 to 300 dpi is sufficient. If there are no pictures scanning greyscale or B & W will also shrink the size of the file immensely. B&W scanning willl always give you the smallest sized file. Lastly, the most efficient scanning is usually done by scanning to TIFF and importing the TIFF into Acrobat. This will give you the best results for text. Some scanner software will scan to jpg and even if scanning to pdf it will use jpg settings which will give the nice results when there are images, but do a poorer job of keeping the text crisp.

    H
    huck999Author
    Participant
    December 3, 2011

    Thanks for the reply.

    I could not find PDF optimizer.  How do you find it?  I didn't find any reference to it in the help file either.

    R
    Rakesh_S
    Participant
    December 3, 2011

    The steps provided as below has been tested on Acrobat X Pro. However as I do not have Acrobat 9 please look for the Optimized PDF option at your end. (NOTE: In Acrobat 9 it might be "Advanced > PDF Optimizer")

    1. Go to "File" > "Save as" > "Optimized PDF"

    NOTE:

    - Now you will be on the PDF Optimizer window as above.

    - You can change "Make compatible with" option per your requiremt)

    2. Select Settings as "Custom"

    NOTE: You will be prompted to "Save current settings as" that you can use to downsample future documents

    3. Check mark "Images"

        a. Quality as "Minimum"

    NOTE:

    - The above settings optimized the 837 KB file size to 410 KB

    - You can try to experiment by changind other options as well at your end.

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