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https://issues.apache.org/jira/browse/PDFBOX-2364?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14145130#comment-14145130
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John Hewson edited comment on PDFBOX-2364 at 9/23/14 5:57 PM:
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Ok, I've figured it out, the behaviour of the "Interpolate" flag isn't strictly
specified and is left to the "conforming reader" to choose. Page 2 of
mori-cvpr01.pdf from PDFBOX-2302 shows that Acrobat uses nearest-neighbour when
scaling up small images on the page. However, the file from PDFBOX-2338 which
this issue is about, renders smoothly in Acrobat. In both cases, the
"Interpolate" flag is not set, the difference is that the second PDF has images
which are being scaled _down_.
It seems that Acrobat honours the Interpolate flag when scaling up, but not
scaling down, which makes some sense.
was (Author: jahewson):
Ok, I've figured it out, the behaviour of the "Interpolate" flag isn't strictly
specified and is left to the "conforming reader" to choose. Page 2 of
mori-cvpr01.pdf from PDFBOX-2302 shows that Acrobat uses nearest-neighbour when
scaling up small images on the page. However, the file from PDFBOX-2338 which
this issue is about, renders smoothly in Acrobat. The difference is that the
second PDF has images which are being scaled _down_.
It seems that Acrobat honours the Interpolate flag when scaling up, but not
scaling down, which makes some sense.
> CCITT image renders incorrectly
> -------------------------------
>
> Key: PDFBOX-2364
> URL: https://issues.apache.org/jira/browse/PDFBOX-2364
> Project: PDFBox
> Issue Type: Bug
> Components: Rendering
> Affects Versions: 2.0.0
> Reporter: John Hewson
> Labels: CCITTFaxDecode, ccitt
> Attachments: PDFBOX-2338-2038866.jpg, PDFBOX-2338-p6.jpg
>
>
> The file from PDFBOX-2338 has a CCITT image on p6 which renders incorrectly.
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