[jira] [Resolved] (PDFBOX-2127) Optimize calls of getPixel in SampledImageReader and PDImageXObject

["Andreas Lehmkühler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PDFBOX-2127?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andreas Lehmkühler resolved PDFBOX-2127.
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       Resolution: Fixed
    Fix Version/s: 2.0.0

I've applied the proposed patches in revision http://svn.apache.org/r1601689 and added some minor improvements based on the same idea.

Thanks for the contribution!

> Optimize calls of getPixel in SampledImageReader and PDImageXObject
> -------------------------------------------------------------------
>
>                 Key: PDFBOX-2127
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-2127
>             Project: PDFBox
>          Issue Type: Improvement
>    Affects Versions: 2.0.0
>            Reporter: Petr Slaby
>            Assignee: Andreas Lehmkühler
>             Fix For: 2.0.0
>
>         Attachments: 000048.pdf, GetPixel.patch
>
>
> When calling Raster#getPixel() in a loop, it is a good practice to make sure that the result array is allocated only once. SampledImageReader#getStencilImage() and PDImageXObject#applyMask() fail to do that. When rendering the attached example, this results in allocating 24 053 760 arrays containing 3 floats, which is about 0.5GB of data if my math is right. Also, I have noticed that SampledImageReader#getStencilImage() reads and sets the same data w/o modification if alpha of a pixel != 255. 
> After applying the attached patch, rendering time of the document drops from 8.5s to 7.4s. Not as much as I have expected - array allocation and the garbage collector seem to be fast - but still...
> Note: Rendering of the document is wrong, it does not find some of its fonts, but that is irrelevant for this issue.



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