[
https://issues.apache.org/jira/browse/PDFBOX-2681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14317910#comment-14317910
]
Jon Wu commented on PDFBOX-2681:
--------------------------------
Logically it makes sense that you'd calculate the gradient in the original
colorspace, but I was wondering if I somehow converted all color values to RGB
first, whether I'd come out with a gradient that looked like Adobe's rendering
since gradient-test-photo-rgb-pdfbox.jpg which was rendered from the RGB PDF
looks fine. If so, would that mean that it's the more correct way to go if
you're targeting RGB from CMYK? That said, maybe that's way off from reality -
I don't know much about the PDF internals at all.
If we're not likely to be able to fix PDFBOX-1206 officially, I'd love to get
the fix and try to build my own jar. Maybe I can switch in the Adobe ICC
profile as well to see how that works too. Can send via [my first name] at zyzz
dot com.
> 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: gradient-test-illustrator.jpg, gradient-test-pdfbox.jpg,
> gradient-test-photo-illustrator.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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
