PHP GD problem--not enough permission to make image?

Error:

Warning: imagejpeg() [function.imagejpeg]: Unable to open 'images/xxx/xxx.jpg' for writing: Permission denied in /usr/www/users/xxx/resources/func.createthumbs.php on line 48
images/xxx/xxx/xxx.jpg
Warning: Cannot modify header information - headers already sent by (output started at /usr/www/users/xxx/resources/updatethumbs.php:17) in /usr/ww开发者_Python百科w/users/xxx/resources/func.createthumbs.php on line 3

So... How can I change the permission? This is being run on a shared server--is it possible?

Check images' chmod and set it to 644 - via FTP client or shell. How change permissions ? Depends of your FTP client.

use your ftp client to set 0777 (or writing for everyone) for the directory images/xxx/xxx/

and it is not GD problem