[Typo3] error:imagecreate not defined, when trying to use gifbuilder

[robert rottermann]

Hi there,
I have installed typo 3 on a Linux box (SuSE 9.3).
Whenever I try to use gifbuilder I get an error stating that a call to 
an unknown method imagecreate is being executed.

On an other computer where the Lamp package is installed everything 
works fine.
I assume therefore that I just missed to install a library. but which one ??

Thanks for any advice.

Robert