使用codeigniter进行图像上传和操作

I'm trying to upload an image and have its thumbs immediately after uploading and get the link(path) when I click the thumbs. So I found this video in youtube that provided me exactly what I needed but I get these errors eventhough I was thorough in following the codes. Everyone in the comments seems to be not having any issues with the codes shown in the vid but me and my friends followed it individualy but we are having the same issues. I really wanted it to work.

Here is the video tutorial I was talking about: https://www.youtube.com/watch?v=RG0NAVPNvoo

And these are the errors:

A PHP Error was encountered

Severity: Warning

Message: scandir(): Directory name cannot be empty

Filename: models/gallery_model.php

Line Number: 49

A PHP Error was encountered

Severity: Warning

Message: array_diff(): Argument #1 is not an array

Filename: models/gallery_model.php

Line Number: 50

A PHP Error was encountered

Severity: Warning

Message: Invalid argument supplied for foreach()

Filename: models/gallery_model.php

Line Number: 52