Mixed results using PDF Shrink and PDF optimizer tools on sheet music

Posted: August 3, 2012 in iPad, scanning, sheet music, tablet

I’ve been adding PDF music scores to my Dropbox account for easy access from both iPad and laptop, but the storage space in my free account is starting to fill up.  So I got motivated to try some PDF compression and optimization tools so that I can postpone the day when I run out of space.  (If you want to help me postpone that day, sign up for Dropbox through my affiliate link and I get rewarded with 500MB of additional space.)  Also, some of these PDF tools claim to deskew crooked scans – something that my old photocopies could use.

I tried three tools: PDF Shrink, A-PDF Scan Optimizer, and Adobe Acrobat.  I experimented with scores I’ve scanned myself, as well as scores that I downloaded from IMSLP.  My goal for my music library (and maybe it’s overambitious) is to have a single PDF file for each piece that is 1) as small as possible, 2) legible on the iPad, and 3) prints out with a nice crisp image for my pianist.  Here’s how the PDF tools measured up.

PDF Shrink: I’m on the fence

PDF Shrink has a 10-day free trial version that you can download.  Some of its pluses are that it has a batch mode so you can process multiple files at a time, and the settings are very simple.

Here is a test on a full opera score.  I ran PDF Shrink in “Print” mode which should yield the best image quality at the expense of file size.  The size reduction was very good – the file shrank by 75%.  Below is the image output.  Click on it to see it in full size.  In this case, I’d have to give it a thumbs-down.  The staff lines are just too blotchy.  Maybe it would be ok if you knew the score well and were just using it as a roadmap, but for detailed study, it would be difficult to work with.

PDF Shrink was more effective with the larger-print piano-vocal score below.  (Click image for full size.)  Size reduction was about 66%, and again, this was “Print” mode.  The sharpness of the text suffers a bit, but I would be ok with this on the iPad.  However, I’m just not sure whether I would want to email a file with this image quality to my pianist (compared with the original file).

PDF Shrink experts in the blogosphere, can you suggest anything else I can try in order to preserve more image quality while also achieving some file size reduction?

A-PDF Scan Optimizer: Useless

A-PDF Scan Optimizer has a free trial version which watermarks your output PDF file.  It also has a batch mode, as well as an option to deskew your scans, which some of my old photocopies badly need.

In practice, though, A-PDF Scan Optimizer basically did nothing.  I got no file size reduction unless I set the downsampling resolution to a ridiculously low number (like 96dpi, which more or less yielded a garbage image).  And, my skewed pages did not get deskewed.

Adobe Acrobat: Best result, but $$$

I don’t own a license for Adobe Acrobat, but my spouse was nice enough to let me use it on his work laptop for the purposes of this test.  Here is the same bit of opera score that I tested with PDF Shrink (again, click image for full size).  In Adobe Acrobat, file size reduction was about 50%.  I’m a lot happier with this combination of image quality and file size reduction.

I tried some piano-vocal scores too.  By futzing with the settings, I was able to get 30-50% size reduction while also producing files that I’d be fine with emailing to a pianist.  And, my crooked scans got deskewed beautifully!

Here are the tools and settings I used.  First, I ran the “Optimize Scanned PDF” tool on the file with these settings: Quality set to one notch lower than the highest setting, Background Removal on High, everything else turned off.  (If you start losing staccati or other small markings, you may need to turn down the Background Removal.)

Then I ran the “Reduce File Size” tool.  For this experiment, I used the “Acrobat 9.0 and later” compatibility setting, which does indeed result in good file size reduction.  In practice, though, you might want to use a wider compatibility setting, in case your pianist is a couple of versions behind on Acrobat Reader.

So far, so good – so what’s the catch?  Price.  An individual user license for Adobe Acrobat is $200 or so, which is pretty steep if your employer or educational institution is not footing the bill.  (The other two tools run $35-40.)  Honestly, I don’t see myself shelling out that kind of cash for Adobe Acrobat in order to perform this task.  Also, I’m not sure if Acrobat has a batch mode for processing multiple files at once – that would be something to check out. [UPDATE: Matt Libera at Performing Arts Technology @ UNCG has posted detailed instructions about batch processing for PDF optimization in Acrobat, plus useful advice about optimization settings and metadata tagging.  Thanks, Matt!]


I like the results from Adobe Acrobat the best, but the license fee is not in the cards for me, so I guess I’ll stick to my full-sized PDF scores for now.  However, if you have access to Acrobat through work or school, you should definitely give it a whirl.  And frankly I’d recommend that you try out PDF Shrink and A-PDF Scan Optimizer at least once, too, since they’re free to try.  Technology in Music Education has reported good results with PDF Shrink for scanning sheet music.  Also, sometimes different files from different scanners yield different results.  It’s possible that my scanner is doing a good enough job that some of these tools are hard-pressed to find any additional space savings.

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  1. Chris says:

    If you send PDF shrink an e-mail with an attached score, they will be happy to examine your score and suggest optimized settings to preserve your scan.

    By chance, have you tried scanning with the settings I use?

    Also….I always (ALWAYS) keep the larger file, knowing that there will be a day when the size of the file doesn’t matter. Or in the case of Chroatik, which will take your music and put it into their format (coming soon), I would also send the larger file.

    • Tech4Singers says:

      Chris, thanks for the suggestion on PDF Shrink. I will see if the makers of PDF Shrink can give any guidance on better settings. I am scanning my own files at 300 dpi black and white, but the specific examples in my blog post are from IMSLP. Not sure what resolution those are, but it’s possible that I can find that info on the IMSLP page.

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