为什么codeigniter会给我这个错误？

I'm trying to make thumbmails of user imaes. However, I always get 'path to the image is incorrect."

my code:

$settings = array(
            'source_image' => '/videotuts/profilepic/userimg.png',
            'create_thumb' => TRUE,
            'new_image' => '/videotuts/profilepic'
        );
$this->load->library('image_lib',$settings);

$r = $this->image_lib->resize();

Does it matter that codeigniter is not installed in my website root?

Looking at all the answers and comments, let me assume that you have codeigniter in folder /htdocs/videotuts/, notice there is a / in the starting. So you index.php is located in htdocs/videotuts/index.php. Codeigniter libraries will follow any path respective to index.php and hence there should be a path /videotuts/profilepic/userimg.png under /htdocs/videotuts/or the full path should be '/htdocs/videotuts/videotuts/profilepic/userimg.png'. If its not the same, remove the unwanted folder name from your paths. You don't need to use APPPATH or FCPATH or BASEPATH. 2ndly, if you are creating thumbnails, I hope you have correctly set read write perms for image folders.

Is that folder actually at that absolute path on your server? If not, experiment with using the APPPATH constant.

'source_image' => APPPATH.'videotuts/profilepic/userimg.png',

If you are using CI 2.0.2, your APPPATH is application folder. You should use FCPATH, try this:

'source_image' => FCPATH.'videotuts/profilepic/userimg.png',