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https://issues.apache.org/jira/browse/PDFBOX-2681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14320784#comment-14320784
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John Hewson edited comment on PDFBOX-2681 at 2/13/15 9:30 PM:
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Agreed that the PostScript and the PDF look identical. I presume that's the
idea.
What looks different is the gradient-test-photo.pdf file when rendered by
Acrobat vs PDFBox. You need to render using the SWOP v2 profile with PDFBox,
the easiest way is to drop into the icc resources directory and change the
hardcoded filename in DeviceCMYK. Even when rendering with SWOP v2 there is a
subtle difference in the colors in Acrobat vs PDFBox. The PDFBox rendering is
more light and blue, this is only really visible when overlaying the two images
on top of each other and switching back and forth the between them.
I've attached [^acrobat-vs-pdfbox-swop.png] to show the difference.
was (Author: jahewson):
Agreed that the PostScript and the PDF look identical. I presume that's the
idea.
What looks different is the gradient-test-photo.pdf file when rendered by
Acrobat vs PDFBox. You need to render using the SWOP v2 profile with PDFBox,
the easiest way is to drop into the icc resources directory and change the
hardcoded filename in DeviceCMYK. Even when rendering with SWOP v2 there is a
subtle difference in the colors in Acrobat vs PDFBox. The PDFBox rendering is
more light and blue, this is only really visible when overlaying the two images
on top of each other and switching back and forth the between them.
> Colors inaccurate rastered CMYK source w/ gradient + photo
> ----------------------------------------------------------
>
> Key: PDFBOX-2681
> URL: https://issues.apache.org/jira/browse/PDFBOX-2681
> Project: PDFBox
> Issue Type: Bug
> Components: Rendering
> Affects Versions: 2.0.0
> Environment: Tested on OS X 10.10, Java 1.6 / 1.8
> Reporter: Jon Wu
> Attachments: Shading2Function2CMYK.pdf, Shading2Function2CMYK.ps,
> acrobat-vs-pdfbox-swop.png, gradient-test-illustrator.jpg,
> gradient-test-pdfbox.jpg, gradient-test-photo-illustrator.jpg,
> gradient-test-photo-pdfbox-us-web-coated-swop-v2.jpg,
> gradient-test-photo-pdfbox.jpg, gradient-test-photo-rgb-illustrator.jpg,
> gradient-test-photo-rgb-pdfbox.jpg, gradient-test-photo-rgb.pdf,
> gradient-test-photo.pdf, gradient-test.pdf
>
>
> In the attached gradient-test-photo.pdf, there's a photo with a gradient on
> top of it. The colors in the gradient are CMYK. When rasterizing this test
> file with PDFBox 2.0.0 SNAPSHOT 20150209, the resulting image's gradient is
> different from the original and the colors of the photo under the gradient
> look significantly different vs the display in Adobe tools like Illustrator
> or other compliant PDF readers.
> Issues:
> - Color hue is wrong. Is this a CMYK to RGB issue?
> - Opacity of gradient is wrong and much different. The jpg from Illustrator
> shows much more of the photo without a gradient over it.
> Without a photo, there's still a difference, but it's much harder to see.
> Example in gradient-test.pdf where the same gradient is drawn over a grey
> rectangle.
> If I convert the PDF to RGB in Illustrator first and rasterize the RGB PDF
> with PDFBox, the result is nearly identical between Illustrator and PDFBox so
> this seems like a CMYK conversion issue in both the general color conversion
> and maybe how the gradient is calculated.
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