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https://issues.apache.org/jira/browse/PDFBOX-2364?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14145091#comment-14145091
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John Hewson commented on PDFBOX-2364:
-------------------------------------
We don't use IndexColorModel, so that bug report doesn't apply to us, also
we're not scaling the image, Graphics2D is, so Image.getScaledInstance() isn't
really a substitute.
The image is 1bpc (i.e. binary) rather than grayscale, though the PDF colour
space is DeviceGray. Ultimately the image which is rendered by Graphics2D is
TYPE_INT_RGB because it's converted by DeviceGray#toRGBImage(). Dumping the
image returned by this method shows that it is perfect, which means that the
issues is with Java scaling a standard TYPE_INT_RGB image. Looking at the
image's dictionary the "Interpolate" flag is not set, which means that we're
using the VALUE_INTERPOLATION_NEAREST_NEIGHBOR hint to draw the image, this is
correct, but Java's nearest neighbour scaling is particularly poor.
> 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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