[pdftex] Pdftex corrupts included pdf images

[Marco Bosch]

Hello,

I'm writing my thesis with pdftex and everythings works smoothly except the
inclusion of some scanned pictures and png files. I've converted these 
files to
eps files and used epstopdf to convert them to pdf files. The files look 
perfectly
if viewed with acroread. However, when I include them in my document with
\includegraphics, some images look like negatives of what they are 
intended to
be (and furthermore, they are distorted).

I've read that this problem has come up before and the suggestion was to 
upgrade
to a newer version of pdftex. However, I do not want to upgrade my 
version of pdftex
at the moment. The risk of something going wrong and screwing up my 
whole tex
system seems to be too big at the moment.
I know that I can include the files directly as a png file with 
\pdfimage. However,
I also want to use normal latex on the file.

Thus, I'm wondering if there is some workaround to solve the problem. 
Are there
any options I can give to includegraphics, or should I use something like
\textcolor{black} before the \includegraphics statement?

greetings,

Marco Bosch