Why do small pdf's eat up all of the memory in Preview?

Discussion in 'Mac Basics and Help' started by spooner1887, Mar 12, 2012.

  1. spooner1887 macrumors newbie

    Joined:
    Oct 11, 2010
    #1
    So I have noticed this issue with when using Preview to view pdfs. If a pdf has several pictures (esp. color), Preview seems to consume extraordinarily large amounts of memory when rendering the images in these pdf's.

    Recently I generated a power point presentation with 9 graphs (originally *.eps which were converted to *.jpg and then imported into power point). I then printed it as a pdf and the resulting pdf was only 20.8MB. When I view it with Preview, Preview consumes 1.54GB of Real Mem. This is with starting Preview afresh without having viewed other files prior or at the same time.

    This is absolutely absurd, and I was wondering if there is something I can do when generating pdf's to prevent this issue from coming up? Evidently I do not understand how pdf viewers work and why this much memory would be necessary. I have also noticed this issue with other image intensive (yet relatively small) pdf's. I just find it shocking to believe that it needs that much of the system resources to render such a puny image. Thanks!
     
  2. snberk103 macrumors 603

    Joined:
    Oct 22, 2007
    Location:
    An Island in the Salish Sea
    #2
    Don't know the specific answer to your question... but don't fuss the memory thing unless it actually starts to impact your system. The OS has memory management and it may be claiming that much memory because it can ... that is to say - because you don't appear to be doing much of anything else at the time Preview may be claiming as much memory as it may need incase you decide to do something that needs RAM.

    For your next experiment, open up the Preview stuff again, but this time with a bunch of other stuff already open. See if Preview takes the same RAM.

    For comparison the rule of thumb is that for each photo you open in Photoshop you need about 7x or 8x the RAM as the file size.

    Luck.
     
  3. wlh99 macrumors 6502

    Joined:
    Feb 7, 2008
    #3
    It is probably related to rasterizing the pdf for display., or decompressing a compressed raster image.

    .eps and .pdf files are vector based, which means for example for a square, you only need to define 4 points. However to display that square on the screen, you need to know every pixel within the sqaure. So you go from 4 points to thousands, plus the overhead to make the calculations.

    Depending on the printed size of the graphics(were they meant to print 8.5 x 11?), they can get quite large quickly. As stated snberk, unless you notice your computer slowing down significantly, I wouldn't worry too much.
     

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