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https://issues.apache.org/jira/browse/PDFBOX-5852?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17882144#comment-17882144
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Andreas Lehmkühler edited comment on PDFBOX-5852 at 9/16/24 5:59 PM:
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I've replaced the map for the pre-calculated color values with a
two-dimensional array. It speeds up rendering by a factor 2 at 100%, a factor
of 5 at 200% and a factor of 10 at 400% using the pdf debugger.
I guess there is some positive effect concerning the memory consumption as
well, but not as clearly as the effect on the rendering time
[~tilman] please run some rendering tests to be sure there aren't any
regressions. I'm going to backport the changes to 3.0.x and 2.0.x if everything
works as expected
was (Author: lehmi):
I've replace the Map for the pre-calculated color values with a two-dimensional
array. It speeds up rendering by a factor 2 at 100%, a factor of 5 at 200% and
a factor of 10 at 400% using the pdf debugger.
I guess there is some positive effect concerning the memory consumption as
well, but not as clearly as the effect on the rendering time
[~tilman] please run some rendering tests to be sure there aren't any
regressions. I'm going to backport the changes to 3.0.x and 2.0.x if everything
works as expected
> Hi CPU and memory usage when converting a PDF with type 4 shading
> -----------------------------------------------------------------
>
> Key: PDFBOX-5852
> URL: https://issues.apache.org/jira/browse/PDFBOX-5852
> Project: PDFBox
> Issue Type: Wish
> Components: Rendering
> Affects Versions: 2.0.28
> Reporter: Larry Lynn
> Assignee: Andreas Lehmkühler
> Priority: Major
> Fix For: 3.0.3 PDFBox, 4.0.0
>
> Attachments: minimal.pdf
>
>
> We've observed excessive CPU and memory consumption when converting a PDF to
> images when the PDF contains type 4 shading. This is especially noticeable
> when the conversion is done with a high DPI. Can this be improved?
>
> Conversation from the PDFBox users mailing list follows
> Initial email:
> {quote}
> Hi CPU and memory usage when converting a PDF with type 4 shadingHello PDFBox
> users and maintainers,
> We have a PDF that causes performance problems when we use PDFBox to
> convert it to an image with renderImageWithDPI(). We're calling
> renderImageWithDPI()
> with 650 DPI. I realize this is a very high value - we're using it for
> high fidelity original images that will later be downsampled. On my work
> laptop which has fairly strong hardware, the conversion takes 25 minutes
> and consumes 20GB of memory. CPU and memory usage is reduced if we use a
> lower DPI.
> The PDF is 1 page long. It contains type 4 shading / Gouraud free form
> triangle meshes. We've been aware of some performance issues with type 4
> shading for a little while now, but the PDFs that contained the type 4
> shading belonged to our customers and we were not authorized to share
> them. We finally found a problem input document that is non-sensitive and
> that we are authorized to share. I've attached a copy of the problem PDF
> to this email.
> I searched the archives for the users and the developers mailing list and I
> didn't find anything specifically about this issue.
> I searched through the PDFBox jira tickets and I found a couple of tickets
> that looked similar: PDFBOX-2901 & PDFBOX-4491. PDFBOX-2901 seems to most
> closely describe what we're seeing, but that was closed in PDFBox 2.0.0,
> and our issue still reproduces with PDFBox 2.0.28.
> Should I refer this issue over to the developers mailing list or create a
> PDFBox Jira ticket for this?
> Thanks and Regards,
> Larry Lynn {quote}
> Response:
> {quote}
> Hi,
> Yes shading can be very slow, especially at high dpi. The attachment
> didn't get through, please upload to a sharehoster or create a ticket.
> If you need to register then add a meaningful text, e.g. the subject of
> this post so we know you're not a spammer. Also retry with 2.0.31 and
> 3.0.2 just to be sure. However I'm pessimistic that this can be fixed.
> Tilman {quote}
>
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