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From "Tilman Hausherr (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PDFBOX-2050) Add predictor to LZW filter
Date Fri, 02 May 2014 04:16:15 GMT

    [ https://issues.apache.org/jira/browse/PDFBOX-2050?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13987307#comment-13987307
] 

Tilman Hausherr commented on PDFBOX-2050:
-----------------------------------------

I did the optimizations; The Flate filter is much faster, but the time spent in that filter
isn't very high anyway (in my test, 17ms before and 5ms after optimizations - of a rendering
of 3 PDF files that took one minute). But we're done such optimizations before (PDFBOX-1006),
so I'll do this too. Done in rev 1591811 for the trunk, and rev 1591812 for the 1.8 branch.

> Add predictor to LZW filter
> ---------------------------
>
>                 Key: PDFBOX-2050
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-2050
>             Project: PDFBox
>          Issue Type: Bug
>    Affects Versions: 1.8.4, 1.8.5, 2.0.0
>            Reporter: Tilman Hausherr
>            Assignee: Tilman Hausherr
>            Priority: Minor
>              Labels: LZW
>
> According to the PDF spec "LZW and Flate Predictor Functions", both can have post processing
with predictors. It is implemented for Flate but not for LZW. I am adding this by using the
existing code from the Flate filter, which I will be moving into a helper class.
> While looking at the Flate filter, I noticed that its footprint is higher than needed,
i.e. there is too much buffering. I will test this separately and commit only if I can measure
an improvement.



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