Python if or not

i have a an if statement like the one below

if (not(fullpath.lower().endswith(".pdf")) or 
    not (fullpath.lower().endswith(tuple(settings.imageExtensions)))) :

The problem is that none of those works and it gets in the if function if the file endswith .pdf or one of the other extensions. What is the best way to do this? FYI i cannot put .pdf in the tuple