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Scribus => PDF Generation => Topic started by: paoloquaglino on May 21, 2012, 09:52:40 pm

Title: PNG opacity not exported to PDF
Post by: paoloquaglino on May 21, 2012, 09:52:40 pm
Hi,
I have a document with many pictures, some of them are jpg, some png.
I applied to many of them some opacity (I mean Properties->Colors->Transparency settings->Opacity) to make them partially transparent.
When I export to PDF, JPGs are ok, PNGs are exported like if they were 100%. ???
The same I get if I apply transparency with Gimp and import the result!
Please note that the fully transparent pixels of a PNG stay transparent. :o
I tried different settings (eg export colors for transparent pixel, exporting from win+photoshop, and of course different PDF versions, different image compression......)
The same I get with scribus on windows.
If I "Save to Image" everything is ok. :-X
Please note that for some images I need to use PNG format because I want them "shaped".

Any ideas...??
Thanks

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Scribus 1.4.1 with Ubuntu 10.4 (x64)
Title: Re: PNG opacity not exported to PDF
Post by: paoloquaglino on May 22, 2012, 03:08:02 am
UPDATE

Actually the document IS exported correctly, since all transparencies look right with Adobe Acrobat Reader (both Linux and Windows versions)
But the Scribus Print Preview is wrong (and Evince too), so it may not be a Scribus problem...

Title: Re: PNG opacity not exported to PDF
Post by: a.l.e on May 22, 2012, 02:17:59 pm
afaik, ghostscript, which is used for the preview, does not support transparencies. (at lest not with basic settings: it can be used to flatten transparencies, so there must be ways to get gs to treat them right.)

the solution here is simple: don't use the preview (which is imo useless... except for some very specific workflows)

evince (and most free pdf reader) don't support transparencies, either.

so, the good ways to preview a document in scribus is to click on the eye button in the lower corner in the status bar or to create a pdf and check it with acrobat reader.

finally, please, make sure that your print shop will support the transparencies!

ciao
a.l.e
Title: Re: PNG opacity not exported to PDF
Post by: paoloquaglino on May 23, 2012, 02:00:08 pm
Ok, I'll follow your directions.
What is very strange to me is that with some pictures (usually jpg) it works correctly, with some other (usually png) it doesn't.
Anyway, I will pre-flatten when in doubt.
Thanks a lot!

Paolo
Title: Re: PNG opacity not exported to PDF
Post by: a.l.e on May 23, 2012, 05:36:41 pm
mmm... strange: jpg does not support transparencies at all :-)
ciao
a.l.e