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From "Tilman Hausherr (JIRA)" <>
Subject [jira] [Commented] (IMAGING-126) TIFF and PNG images should not be bigger than the ones created by java ImageIO
Date Tue, 25 Feb 2014 20:45:26 GMT


Tilman Hausherr commented on IMAGING-126:

I recently improved the class mentioned in PDFBOX-1734, and one of the things I did was to
set RowsPerStrip to the maximum. The ImageIO implementation did not, but their solution wasn't
so bad, they probably had big strips. (I think I wrote this issue before that change)

I agree with your author that correctness-of-implementation has the highest priority. One
has to start from there and then try optimizations, and hopefully have many tests.

Suggestion: put the rowsperstrip as optional parameter. And set a "good" default.

Re LZW compression: It might be useful to check whether the LZW compressor does exactly what
the algorithm is about. I recently discovered an LZW encoded segment in a PDF that wasn't
optimally encoded. Very weird. (This is not so difficult to look at that code; the LZW encoder
is easier to understand than the decoder)

> TIFF and PNG images should not be bigger than the ones created by java ImageIO
> ------------------------------------------------------------------------------
>                 Key: IMAGING-126
>                 URL:
>             Project: Commons Imaging
>          Issue Type: Improvement
>          Components: Format: PNG, Format: TIFF
>    Affects Versions: 1.0
>         Environment: W7
>            Reporter: Tilman Hausherr
>            Priority: Minor
>         Attachments: pdfbox-1870-devicen3-01.png, pdfbox-1870-devicen3-01.tif, pdfbox-1870-devicen3.pdf-1.png,
> I tried to use Apache Imaging for the PDFBOX project (PDFBOX-1734) because of problems
with setting the tiff resolution in java imageio.
> While the code is pretty nice, I found that the generated images are sometimes much bigger
in size than the ones generated by java imageio.
> Example:
> pdfbox-1870-devicen3-01.png 50 KB (imageio)
> pdfbox-1870-devicen3.pdf-1.png 70 KB (imaging)
> pdfbox-1870-devicen3-01.tif 401 KB (imageio)
> pdfbox-1870-devicen3.pdf-1.tif 1063 KB (imaging)

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