[
https://issues.apache.org/jira/browse/PDFBOX-2681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14317925#comment-14317925
]
Tilman Hausherr commented on PDFBOX-2681:
-----------------------------------------
The gradient is calculated by having some fixed values and calculating new
values from where with a help of a function. And there are (I think) 4 types of
functions, which can have all sort of parameters. And there are 7 types of
shadings, yours is a type 2 which is a rather simple one.
I know about 2 other java based libs that offset free trial versions. I think
both are somewhat better re: transparency, but both have problems with shadings
(Try rendering the test files from PDFBOX-1915 with them :-) ).
I'll mail you the fix for PDFBOX-1206 at a later time, maybe tonight or
tomorrow night.
> 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]
