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https://issues.apache.org/jira/browse/PDFBOX-1159?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13278767#comment-13278767
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Michael McCandless commented on PDFBOX-1159:
--------------------------------------------
Thanks Andreas!
On the Encoding.java change: you're right, it was unrelated to speeding up
LZWFilter. But I think it's still worth committing: it saves a redundant call
to getName.
It was just a small code improvement I came across while digging into the
LZWFilter...
> Speed up LZWFilter decoding
> ---------------------------
>
> Key: PDFBOX-1159
> URL: https://issues.apache.org/jira/browse/PDFBOX-1159
> Project: PDFBox
> Issue Type: Improvement
> Reporter: Michael McCandless
> Assignee: Andreas Lehmkühler
> Priority: Minor
> Fix For: 1.7.0
>
> Attachments: PDFBOX-1159.patch
>
>
> I noticed that the LZW decoder performance can be improved: it's
> allocating a new byte[] for every byte it visits in the stream. This
> is actually an O(N^2) cost, but N is typically fairly small.
> I changed LZWDictionary to use its own private growable byte[] to
> accumulate each added byte. I also changed it to not pre-enroll all
> initial (0-255) codes, but instead add it (lazily) on demand if the
> code is used.
> I also randomized the TestFilters test, and mixed in some
> "more predictable" patterns, so we get better testing of the filters.
> If the test fails it prints the seed used for the random numbers, so
> we can reproduce the failure.
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