hello Almeida,
if there is a structure like:
/images
/2010
/thumb
/2009
/thumb
....
if i want to match all jpg files in directory images, except jpg files in every thumb directories, what should use?
i try

rewrite ^/images/[^/thumb/]*\.jpg /watermark/image.php?$request_filename;

but it can't work well....
thanks a lot.
regards
solo