[
https://issues.apache.org/jira/browse/PDFBOX-4831?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17295546#comment-17295546
]
Tilman Hausherr commented on PDFBOX-4831:
-----------------------------------------
For some reason JIRA won't let me upload the Upmeyer file, and she no longer
has her website and it's not on the web archive.
Get the source code of PDFBox and build from there, this is easier.
> Rounding errors when rendering non-interleaved binary CCITT image at 1:1
> scale cause gray pixels in output
> ----------------------------------------------------------------------------------------------------------
>
> Key: PDFBOX-4831
> URL: https://issues.apache.org/jira/browse/PDFBOX-4831
> Project: PDFBox
> Issue Type: Bug
> Components: Rendering
> Affects Versions: 2.0.19
> Reporter: Gábor Stefanik
> Priority: Major
> Attachments: 13._Korona_szallo_vegzes_13.09.26.eredeti-1.png,
> 13._Korona_szallo_vegzes_13.09.26.eredeti.pdf, outside-in.pdf
>
>
> I have a 300dpi scanned PDF file with a single CCITT-encoded black-and-white
> image in each page, spanning the whole page. The images all have a resolution
> of 2480x3504.
>
> When I try to render a page from this PDF into a PNG at 300DPI, the resulting
> PNG has some pixels with colors #010101 and #fefefe. The PNG has the same
> 2480x3504 dimensions as the embedded CCITT images, but stepping through the
> PDFBox code reveals it's trying to downscale the image by a tiny fraction of
> a pixel (e.g. to 2479.999964573x3503.9999537378) using bicubic interpolation,
> introducing these "near-black" and "near-white" pixels due to rounding
> errors. Additionally, the actual image conversion code goes to a slow path
> intended for "proper" interpolated scaling, rather than hitting the fast path
> for copying 1:1-scale images.
>
> For now, we worked around this by treating images containing only #000000,
> #010101, #fefefe and #ffffff as binary, but the performance hit from the slow
> path is still there.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
