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Acrobat applying zip compression upon saving

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  • Acrobat applying zip compression upon saving

    Not sure if this has been happening since the introduction of Acrobat, but I am just noticing it now.

    I had a PDF of the interior of a illustrated fiction book. The PDF was 168mb. Upon first examination(through Pitstop) I could that none of the imagery was compressed. Then after saving the PDF (through acrobat 7) the file size goes down to 84mb, and all of the imagery now has ZIP compression.

    Not saying that ZIP compression is a bad, just seems odd that is being applied when I haven't instructed it to be. I went through all of the Acrobat prefs but was unable to find anything that dealt with this.

    Is there anyway of saving a PDF without ZIP compression being applied?

    Thanks in advance.
    Gregg

  • #2
    Re: Acrobat applying zip compression upon saving

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    • #3
      Re: Acrobat applying zip compression upon saving

      Hi Gregg,
      This is certainly odd. I'm able to replicate the same results.

      I tried Save, Save As without image compressed and PDF optimizer without image compressed .... all yields the same file size reduction. This is probably a question for Adobe. It seems to me they tend to change tiny things under the hood without public documentation.

      Comment


      • #4
        Re: Acrobat applying zip compression upon saving

        Yes, it's frustrating. I even turned off all of the compression setting withing PDF OPtimizer, thinking, perhaps, it would tie-in to the save option. But that did not work, still compressed all imagery.

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        • #5
          Re: Acrobat applying zip compression upon saving

          I've noticed this long ago, and it's still there... Distiller applies lossless zip compression to whatever it can: if it detects a large enough area of unchanged color in a bitmap, chance are this image will get zip-compressed AND CONVERTED TO INDEXED COLOR SPACE. The latter will also make those of such images which are grayscale uneditable in Photoshop up to CS2, as it doesn't support indexed grayscale.

          I agree, this shouldn't be hidden and undocumented.

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          • #6
            Re: Acrobat applying zip compression upon saving

            Neither Acrobat nor Distiller will convert to indexed GRAYSCALE, though we
            most certainly DO convert to indexed RGB and CMYK when we are able to do in
            order to get the file size down significantly.

            Since it is 100% lossless and reduces the size of your PDFs, while
            maintaining 100% compatibility with the original PDF 1.0 specification - I
            don't see why we need to document it.

            It is important to keep document size as small as possible while retaining
            the best fidelity of your content - and we will use all technology at our
            disposal to accomplish this.

            Leonard Rosenthol
            Adobe Systems

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            • #7
              Re: Acrobat applying zip compression upon saving

              Thanks for the reply, Leonard. It's always best to hear it straight from the source.

              Not sure if the tone of your response was called for, but appreciate the feedback nonetheless.

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              • #8
                Re: Acrobat applying zip compression upon saving

                Hello Leonard

                I was doing a search on this forum because I have a PDF file from a client that had an indexed CMYK image in it, and found your post here. We wanted to color correct the PDF, but when we got to the indexed CMYK element we were unable to work with it. We tried using Pitstop to change it, but couldn't; we tried Asura to change it; but it didn't fix it either. The last resort was to rasterize the whole PDF file with photoshop in order to be able to color correct the PDF.
                Do you know of a way to convert the indexed CMYK element into a color space that would allow us to color correct it and avoid having to rasterize the PDF file?

                Regards, Jorge

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                • #9
                  Re: Acrobat applying zip compression upon saving

                  > {quote:title=leonardr wrote:}{quote}
                  >
                  > Since it is 100% lossless and reduces the size of your PDFs, while
                  > maintaining 100% compatibility with the original PDF 1.0 specification - I
                  > don't see why we need to document it.

                  The problem is that you cannot edit an image in Indexed RGB, CMYK, or Grayscale.

                  rich

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