Color problem with simple conversion from PDF to PNG

Hi everyone,

I'm trying to convert this PDF file to PNG:

http://www.bvg.de/index.php/de/binaries/asset/download/474870/file/1-1

No problem with GIMP: Just load file, save file to (different file type)

Thought should be no problem with IM as well:

convert -density 100 alexanderplatz.PDF alexanderplatz.png

Unfortunately, colors come out slightly wrong: Most visible is the dark
green line labeled with "S3 S5 S7 S75", which is kind of neon-bright in
the converted image.

As far as I can tell, none of the images contain a color profile. Both
input and output use RGB.

I am using Ubuntu Maverick Merkaat, which comes with ImageMagick 6.6.2-6
2010-12-02 Q16. I am using eog and evince for viewing PNG and PDF.

Best regards,

Andreas