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https://issues.apache.org/jira/browse/PDFBOX-3791?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16007769#comment-16007769
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Tilman Hausherr edited comment on PDFBOX-3791 at 5/12/17 8:27 AM:
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Some thoughts after profiling... Most time is spent in
- graphics.drawImage - this we can't change, or the quality would go down
- ImageReader.read - can't change
- DCTFilter.fromBGRtoRGB - maybe write on the source raster instead of making a
copy? Won't make it faster but will lessen the memory footprint.
- ScratchFileBuffer.read - it is called with small chunks in
SampledImageReader.from8bit, the bytes for 1 pixel, thus usually only 3 bytes
at a time. This was done in PDFBOX-2301 [ https://svn.apache.org/r1684745 ] to
lessen the memory footprint. Reverting that change makes it about 20% faster
but increases the memory footprint, obviously. Maybe make a compromise by
reading one row at a time.
was (Author: tilman):
Some thoughts after profiling... Most time is spent in
- graphics.drawImage - this we can't change, or the quality would go down
- ImageReader.read - can't change
- DCTFilter.fromBGRtoRGB - maybe... maybe write on the source raster instead of
making a copy?
- ScratchFileBuffer.read - maybe... it is called with small chunks in
SampledImageReader.from8bit, the bytes for 1 pixel, thus usually only 3 bytes
at a time. This was done in PDFBOX-2301 [ https://svn.apache.org/r1684745 ] to
lessen the memory footprint. Reverting that change makes it about 20% faster
but increases the memory footprint, obviously. Maybe make a compromise by
reading one row at a time.
> Long rendering time
> -------------------
>
> Key: PDFBOX-3791
> URL: https://issues.apache.org/jira/browse/PDFBOX-3791
> Project: PDFBox
> Issue Type: Bug
> Components: Rendering
> Affects Versions: 2.0.5
> Environment: windows
> Reporter: Esteban Nicolas Ruiz
> Attachments: slowrender.pdf
>
>
> Attached pdf file takes too long (more then 9 secs) to render in PDFDebugger
> (this is a simplified version of a real life pdf that I can not publish for
> privacy reasons, it takes 57 seconds to render and it contains 56 images and
> some text).
> I have tried with the options provided in
> https://pdfbox.apache.org/2.0/getting-started.html but performance is the same
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