# [pdftex] bug with included transparent graphics

Jim Diamond Jim.Diamond at acadiau.ca
Sat Dec 29 16:55:29 CET 2007

Hi all,

Using pdftex (TeXlive 2007, pdfTeXk, Version 3.141592-1.40.3 (Web2C
7.5.6)), I am trying to create presentations using an image with a
transparent background as well as an image with an (overall) alpha
value of 1/4.

The resulting PDF file looks OK in both kpdf and xpdf (on Slackware
12.0), but in acroread 7.0.9 and 8.1.1 any page containing an image
(PNG or PDF) with transparency has the other colours on the page
screwed up a bit.

For example, here is a LaTeX example, using a example modified from
one on this list about a year ago; the referenced image can be d/l'ed
from http://www.libpng.org/pub/png/img_png/stefan_255_rgba.png

-----------------------------------------

\documentclass{beamer}
\mode<presentation>
{
\usetheme{Madrid}
\setbeamercovered{transparent}
}

\usepackage{ifpdf}
\usepackage{graphicx}
\usepackage{color}
\ifpdf
\hypersetup{%
pdfpagemode=FullScreen,
pdfpagetransition={Wipe /Di 0 /D 0.5}
}
\fi

\title[Beamer and png2pdf]{Using png2pdf with the beamer class}
\author[Krause]{D.~Krause}
\subject{png2pdf}

\begin{document}
\beamertemplateshadingbackground{yellow!50}{magenta!50}

\begin{frame}
\frametitle{NO Image over transient background}
This is some text
\end{frame}

\begin{frame}
\frametitle{Image over transient background}
\includegraphics{stefan_255_rgba.pdf}%
\end{frame}

\end{document}

-----------------------------------------

At least on my system, the colours in the second page are different
than on the first page.  Other tests show that the colours of other
included images get messed up as well.

So... assuming my system is not the only one in the world with this
problem (anyone care to let me know?), can anyone
(a) suggest a work-around, and/or
(b) confirm that this is an Acroread bug, as opposed to a pdftex bug
(which seems likely, unless xpdf and kpdf have work-arounds or
offsetting bugs already built in).

Thanks

Jim


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