# PDF Language and Specifications

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## Different font rendering depending on image transparency

### Sep 3, 2010 12:24 PM

Hi,

this is a cross-post from the Adobe Reader forum, where no one was able to help me. It is about PDF rendering issues in Acrobat Reader, concerning pdf files created with latex. I would be glad if you could help me out; I hope the "PDF language" forum is the right place to ask.

bersbers wrote:

Hi,

please take a look at this file:

http://www.jtartlabs.com/test/test.pdf (this is not my server and not my files, but they illustrate my problem)

The two pages in this file render differently on my system, as can be seen here:

Reader 9.3.4, Windows 7 x64, also on Windows XP SP3 32 bit

The file was created using tex and this minimal example:

\documentclass{book}
\usepackage{graphicx,lipsum}

\begin{document}
\lipsum[1]
Surrounding text is NORMAL
\includegraphics{singleclickbutton2}
\lipsum[5]
\newpage
\lipsum[1]
Surround text is BOLD
\includegraphics{singleclickbutton3}
\lipsum[5]
\end{document}


You see that there should be no difference in the pages except for two different image files, but obviously there is. This effect goes away as soon as I disable the "Smooth text" option, but this is ugly and I cannot expect my readers to do so.

It SEEMS that part of the problem is that singleclickbutton3 has some transparency information, while singleclickbutton2 does not. (All the files are available at http://www.jtartlabs.com/test/).

What causes this issue? More important, what can I do to prevent it - either in tex or using a postprocessor?

Thanks,

bers

Replies
• Currently Being Moderated
Sep 3, 2010 1:56 PM   in reply to bersbers

It's an aspect of the implementation of the PDF standard in Acrobat concerning the choice of default "transparency blending space" when a producer doesn't include an explicit one in the PDF.

The way to correct it is for the PDF producer to ensure that when all content on the page is in RGB, that an RGB-based blending space be specified in the page's transparency group.

I believe that the current version of PdfTeX do the right thing - but this file was produced with an older version.

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Oct 17, 2010 1:58 AM   in reply to lrosenth

Hey everybody,

i have the same problem and an update to a new version of Miktex has not solved the problem. Since nobody posts something to the thread any longer, I am wondering if that problem is fixed, and i miss the fix, or if the solution is posted somewhere else?

Could anybody give me a hint how to circumvent that problem?

Kind regards,

Ede

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Oct 17, 2010 6:37 AM   in reply to bersbers

Can someone post an updated sample and I'll investigate?

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