Creating thumbnails?

[h4x0rmx]

I'm working on a small site that will have some picture galleries.
Each time the administrator creates a gallery, a small version of the original picture (thumbnail) is required along with the original/big picture.
These pictures are stored on a DB.
I was wondering if there's a way to create the thumbnail with the big picture as a base on the server without using any extra libraries?
You know, I'm using a shared hosting service!
Any suggestions will be appreciated!

[Weedpacket]

You could, but you wouldn't want to unless you're into parsing binary files and bit manipulation. You'll need to write a program that decodes image files into pixels, then scale the pixel array, and then write the image file. All from scratch.

Have you verified that GD-Lib is not installed?

[h4x0rmx]

OK! I have checked and I do have GD support (v.2), but now I have some other questions.
I've looked for some tutorials and there seem to be some good ones, but I haven't tried them myself. Anyways I'd like to know something before I start doing anything else:
As I said, the images are being stored on the db. As far as I understand the thumbnails are created on the fly, so there wouldn't be any need for storing them on the db. When I display the pictures on the main site, I use an external file so I have something like:
<img src="get_image.php?id=1" />
I've been trying to use functions like [FONT=Courier New]getimagesize[/FONT] on this script, but won't work ([FONT=Courier New]getimagesize("get_image.php?id=1")[/FONT]), I might be using it wrong, though.
Do you think there will be a way to use the gd functions to generate the thumbnails once the pictures are stored on the db?
or... should I generate the thumbnails at upload time and store them on the db also?

Any suggestions will be appreciated!
Thanx!