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https://issues.apache.org/jira/browse/PDFBOX-1996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13961465#comment-13961465
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John Hewson commented on PDFBOX-1996:
-------------------------------------

You're quite right, I was looking at the input value instead of the output 
value. The output is indeed an int[], so ignore the 1-element part of my 
comment above. The rest still applies, except instead of 1 1-dimensional byte 
array an n-dimensional array could be used instead. However, as 5KB is still 
tiny I see no problem with just using a HashMap.

> PDSeparation optimization
> -------------------------
>
>                 Key: PDFBOX-1996
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-1996
>             Project: PDFBox
>          Issue Type: Improvement
>          Components: Rendering
>    Affects Versions: 2.0.0
>            Reporter: Dave Smith
>            Priority: Minor
>         Attachments: pdfbox.patch, pdfbox.patch
>
>
> I have a 4 page black and white pdf that takes 32 seconds (8 seconds a page) 
> to render. It uses a Separation color space and it has to run numerous 
> functions per pixel that is causing the slow down. I have a patch where I pre 
> calculate the black and white pixels and cache them instead of calculating 
> them every time. This optimization gets the page rendering down to less than 
> a second a page. I will attach my patch. I could see going forward caching 
> all calculated colours , but floats in hash maps are tricky.



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