[NTG-pdftex] [ pdftex-Bugs-741 ] wrong colors for included PDF-images (page groups)

noreply at sarovar.org noreply at sarovar.org
Wed Oct 3 20:51:15 CEST 2007


Bugs item #741, was opened at 2007-03-02 00:50
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Category: PDF inclusion
Group: v1.30.0
Status: Open
Resolution: Accepted
Priority: 5
Submitted By: Uwe Stöhr (stoehr)
Assigned to: Martin Schröder (oneiros)
Summary: wrong colors for included PDF-images (page groups)

Initial Comment:
Attached is a PDF 1.4 image. When you include this to a
document the output generated by pdfetex 1.30.6 the
images looks different: The colors are much darker, see
attached PDF result.

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>Comment By: Martin Schröder (oneiros)
Date: 2007-10-03 20:51

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Fix is in the works.

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Comment By: Martin Schröder (oneiros)
Date: 2007-10-01 07:08

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Adding /Group to the /Page is not an option for us (and
probably wrong): What should we do when we have more than
one included pdf on a page and they have different /CS
entries? And why does transparency in an /XObject need an
entry in the /Page? The entry in the /XObject should suffice.

I wouldn't be surprised if AR is faulty here.

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Comment By: Adrian Johnson (ajohnson)
Date: 2007-10-01 02:04

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After adding 

/Group <<
  /CS /DeviceRGB
  /Type /Group
  /S /Transparency
>>

to the /Page object in newfile2-1.pdf it displays correctly
in Acrobat.


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Comment By: Martin Schröder (oneiros)
Date: 2007-10-01 01:04

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The attached file newfile2-1.pdf has a copied page group,
which as I now know, should be correct. Still, AR8 at Linux
shows different colours for it and TestSkizze.pdf .

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Comment By: Uwe Stöhr (stoehr)
Date: 2007-10-01 00:51

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> Why is this WONTFIX?

Sorry, this bug was once closed when this additional info
was not available. -> I reopened this bug.

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Comment By: Uwe Stöhr (stoehr)
Date: 2007-10-01 00:46

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Why is this WONTFIX?

I mean:
> The file TestSkizze.pdf specifies the color blending space
> with "/CS /DeviceRGB" in the transparency group. In
> the PDF produced by pdftex this has been stripped out.

So the bug is that pdftex strips out the color space.
If you really think it's WONTFIX, then tell me what is the
correct way of specifying the color space so that I can
forward this to the Inkscape developers.

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Comment By: Adrian Johnson (ajohnson)
Date: 2007-09-30 15:34

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The file TestSkizze.pdf specifies the color blending space
with "/CS /DeviceRGB" in the transparency group. In the PDF
produced by pdftex this has been stripped out. When the
color space is not specified Acrobat defaults to CMYK. This
results in RGB colors being converted to CMYK, blended in
CMYK color space, then converted back to RGB. This will
produce different results compared to blending the colors in
RGB space.

This problem was also reported to the cairo list:
http://lists.cairographics.org/archives/cairo/2007-September/011471.html


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Comment By: Uwe Stöhr (stoehr)
Date: 2007-03-03 19:41

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> To my eye the Harlequin results are the same for both
> file,

Yes and the result is correct.

> while Jaws has to different results.

In my eyes the Jaws results are identical but wrong.

So it seems that pdftex is not the problem here, but it
would be nice if pdftex could handle page groups in one of
the next releases:
>"PDF inclusion: Page Group detected which pdfTeX can't
> handle. Ignoring it."
So I'm not sure to close this bug or mark it as enhancement.
Thanks for your help.

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Comment By: Martin Schröder (oneiros)
Date: 2007-03-03 15:48

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I've attached the results of two professional RIPs: Global
Graphics Jaws & Harlequin. To my eye the Harlequin results
are the same for both file, while Jaws has to different
results. :-{

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Comment By: Martin Schröder (oneiros)
Date: 2007-03-02 13:16

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Your document is using Page Groups (see PDF Reference
7.3.6). Including pdfs that use this is a grey area; see the
notes in NEWS and pdftoepdf.cc. It works most of the times
and with most RIPs. I'll look into it again, but I don't
have much hope.

Btw: pdftex warns you:
"PDF inclusion: Page Group detected which pdfTeX can't
handle. Ignoring it."

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Comment By: Uwe Stöhr (stoehr)
Date: 2007-03-02 13:05

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> problem in AR7 - but only there.

But how could this be a bug in Acrobat when Adobe set the
standards? Why is this correctly shown before the
pdftex-run. The display is the same here in Acrobat 5 - 8 so
I think they would have fixed it when it's a bug since
Acrobat 5.

Hmm but OK, when I open the result with GSview besides the
GS bug, the color tones are correctly be displayed. So close
this bug report again, when you are sure that pdftex follows
here exactly the PDF-specification.

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Comment By: Uwe Stöhr (stoehr)
Date: 2007-03-02 12:57

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> It's a bug in AR;

No! Acrobat is correct: I created this image with Inkscape
0.45 and exported it the as PDF. I designed e.g. the green
as light green. And Acrobat 7 and 8 shows this exactly as
designed while the pdftex result has wrong color tones, see
the attached screenshots.

(Ghostscript is btw. not able to render the PDF-image
correctly - I reported this to the GS people who confirmed it.)

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Comment By: Martin Schröder (oneiros)
Date: 2007-03-02 01:05

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You don't say it, but I see the same problem in AR7 - but
only there. It's a bug in AR; try kpdf or ghostscript instead.

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