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https://issues.apache.org/jira/browse/PDFBOX-5229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17370187#comment-17370187
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ASF subversion and git services commented on PDFBOX-5229:
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Commit 1891077 from Tilman Hausherr in branch 'pdfbox/trunk'
[ https://svn.apache.org/r1891077 ]
PDFBOX-5229: optimize reading of masked images, by Gunnar Brand; closes #121
> Optimize reading of masked images
> ---------------------------------
>
> Key: PDFBOX-5229
> URL: https://issues.apache.org/jira/browse/PDFBOX-5229
> Project: PDFBox
> Issue Type: Improvement
> Components: Rendering
> Affects Versions: 2.0.24
> Reporter: Tilman Hausherr
> Assignee: Tilman Hausherr
> Priority: Major
> Labels: optimization
> Fix For: 2.0.25, 3.0.0 PDFBox
>
> Attachments: Alfa-p1.pdf
>
>
> From Gunnar Brand:
> {quote}There was a severe performance issue with really big masks if the
> image needs to be scaled to it (i.e. 10000*10000 pixels). Scaling bicubic can
> take 6-10 seconds. This patch tries to switch to bilinear resizing for these
> cases, although the threshold might have to be fine tuned, still.
> There was also a double allocation for the final masked image when we can
> simply use the image since applyMask() is always fed with a newly created
> one. Reference hogging and needless allocation have been removed.
> Additionally the alpha blending routines were very slow, working on pixels.
> There is now a staggered approach by:
> * direct byte masking which is very fast even for big images (right now does
> not work with padded buffers),
> * exploiting data buffer's sample system to merge the alpha component into
> the ARGB image, letting the sample model do the bit masking,
> * slow pixel expansion to reverse premultiply matte values (but using fixed
> point integer arithmetics).
> Additionally also using the interpolation flag of the mask to decide if the
> mask should be interpolated.
> {quote}
> Attached: page 1 of https://archive.org/details/AlfaWaffenkatalog1911
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