Petr Slaby created PDFBOX-2127:
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Summary: 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
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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