[ pdftex-Bugs-723 ] Pale colors when using transparency in PNG graphics
Bugs item #723, was opened at 2007-01-25 07:27 You can respond by visiting: http://sarovar.org/tracker/?func=detail&atid=493&aid=723&group_id=106 Category: Image inclusion Group: v1.40.1 Status: Open Resolution: Accepted Priority: 5 Submitted By: Mark Henning (markhe) Assigned to: Martin Schröder (oneiros) Summary: Pale colors when using transparency in PNG graphics Initial Comment: Hi@all! I hope this is the right place to report this problem: If there is any transparency definition in a PNG file (e.g. transparency by a certain color or given by a mask), then all graphics on the page show pale colors. Graphics on pages before or after this page show normal colors. This is confirmed in several versions of Adobe Acrobat Reader. Ghostview/Ghostscript does not show this behaviour. The reason for this viewer-dependency might be a missing transparency-definition in the PDF file which makes it ambiguous, as reported by Andreas Lobinger in de.comp.text.tex; thread "Blasse Farben bei transparentem PNG in pdftex". ----------------------------------------------------------------------
Comment By: Martin Schröder (oneiros) Date: 2007-01-25 18:05
Message: Logged In: YES user_id=421 Attached the results of rendering this with two professional RIPs (Jaws and Harlequin). I don't see it there... ---------------------------------------------------------------------- Comment By: Martin Schröder (oneiros) Date: 2007-01-25 16:15 Message: Logged In: YES user_id=421 Ah, now I see it. Inded, AR7.0.9 shows a difference. The problem also shows with files generated by pdftex 1.40.1 ---------------------------------------------------------------------- Comment By: Mark Henning (markhe) Date: 2007-01-25 16:08 Message: Logged In: YES user_id=4174 Sorry; I forgot to check the checkbox for uploading the file. ---------------------------------------------------------------------- Comment By: Mark Henning (markhe) Date: 2007-01-25 16:06 Message: Logged In: YES user_id=4174 I rechecked with Adobe Acrobat 7.0 and Adobe Acrobat 7.0.9 on Win2000 SP4, both showed the color differences (see the PNG file I uploaded. It shows a direct comparison.). If you checked the PDF and say that it is O.K., then there must be a bug in Adobe Reader. I will contact Adobe then. ---------------------------------------------------------------------- Comment By: Martin Schröder (oneiros) Date: 2007-01-25 14:53 Message: Logged In: YES user_id=421 I see no problems with AR 7.0.9, kpdf 0.5.1 and gs 8.54 on SUSE 10.1. ---------------------------------------------------------------------- Comment By: Martin Schröder (oneiros) Date: 2007-01-25 14:51 Message: Logged In: YES user_id=421 Pointer to the threat on dctt: http://groups.google.de/group/de.comp.text.tex/browse_thread/thread/758dcc47... An example: http://www.homolog.de/temp/PNGTransparencyBug.zip ---------------------------------------------------------------------- You can respond by visiting: http://sarovar.org/tracker/?func=detail&atid=493&aid=723&group_id=106
Hi Hans and Taco, just a question: do you use PNG transparency purely by the PDF object machinery provided by pdftex, or do you add (via ConTeXt) other dictionaries for transparency definition as well? If the latter, what's normally in there? Regards, Hartmut On Thu, 25 Jan 2007, noreply@sarovar.org wrote:
Bugs item #723, was opened at 2007-01-25 07:27 You can respond by visiting: http://sarovar.org/tracker/?func=detail&atid=493&aid=723&group_id=106
Category: Image inclusion Group: v1.40.1 Status: Open Resolution: Accepted Priority: 5 Submitted By: Mark Henning (markhe) Assigned to: Martin Schröder (oneiros) Summary: Pale colors when using transparency in PNG graphics Initial Comment: Hi@all! I hope this is the right place to report this problem: If there is any transparency definition in a PNG file (e.g. transparency by a certain color or given by a mask), then all graphics on the page show pale colors. Graphics on pages before or after this page show normal colors. This is confirmed in several versions of Adobe Acrobat Reader. Ghostview/Ghostscript does not show this behaviour. The reason for this viewer-dependency might be a missing transparency-definition in the PDF file which makes it ambiguous, as reported by Andreas Lobinger in de.comp.text.tex; thread "Blasse Farben bei transparentem PNG in pdftex".
Hartmut Henkel wrote:
Hi Hans and Taco,
just a question: do you use PNG transparency purely by the PDF object machinery provided by pdftex, or do you add (via ConTeXt) other dictionaries for transparency definition as well? If the latter, what's normally in there?
I don't think there is anything special in ConTeXt. What is going on here anyway? I do not comprehend the dctt comments enough to understand precisely what is (supposedly) missing. Taco
2007/1/25, Taco Hoekwater
I don't think there is anything special in ConTeXt. What is going on here anyway? I do not comprehend the dctt comments enough to understand precisely what is (supposedly) missing.
AR7 (only!) shows different colors on page 1 and page 2. It has been claimed that our support for transparent pngs needs some additional dictionaries etc. on the page. Could somebody please test this with AR8? Best Martin
On Thu, 25 Jan 2007, Martin Schröder wrote:
2007/1/25, Taco Hoekwater
: I don't think there is anything special in ConTeXt. What is going on here anyway? I do not comprehend the dctt comments enough to understand precisely what is (supposedly) missing.
AR7 (only!) shows different colors on page 1 and page 2. It has been claimed that our support for transparent pngs needs some additional dictionaries etc. on the page.
no idea what should be missing (no idea about Transparency either). From the PDF Ref. it looks like everything not there is optional. Maybe Blendmode BM has wrong default in AR7? And it's ok in xpdf and gs (i don't have acroread here). Regards, Hartmut
2007/1/25, Hartmut Henkel
no idea what should be missing (no idea about Transparency either). From the PDF Ref. it looks like everything not there is optional. Maybe Blendmode BM has wrong default in AR7? And it's ok in xpdf and gs (i don't have acroread here).
xpdf, kpdf and gs may be buggy in this area. But the two other rips I tested are not. And there I see no difference. Best Martin
Hartmut Henkel wrote:
Hi Hans and Taco,
just a question: do you use PNG transparency purely by the PDF object machinery provided by pdftex, or do you add (via ConTeXt) other dictionaries for transparency definition as well? If the latter, what's normally in there?
context maintains its own transparency only for text and mp graphic, not for png etc; features like this can best be handles in the macro package anyway since there is not one solution (context does a lot of optimization, sharing etc there; pretty old code btw and unrelated to graphics; well, i do manipulate graphics (duo/multitone stuff) but not transparencies) keep in mind that colors in the viewer may look different starting at the page where the first transparency is encountered; has always been the case in viewers; has to do with some interaction betwene caching, anti aliasing, complex color spaces, etc so, if i use transparencies in a document, i always make sure that on the first page i have a fake one in order to trigger the machinery Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------
participants (5)
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Hans Hagen
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Hartmut Henkel
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Martin Schröder
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noreply@sarovar.org
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Taco Hoekwater