best way to upload and rename an image

[eluser]FuzzyJared[/eluser]
So here is my situation, which I don't think is all that uncommon. I am uploading an image and then creating 3 different sizes of the image through imag_library GD2 and then inserting this information into my database. I have done this much successfully.

What I would like to add into this, is renaming the uploaded image to something unique to ensure that no other image is being overwritten. In the past with other web apps I simply do a time() or other unique id generator and use that in place of the original file name.

Any suggestions on how I would accomplish this, as I don't believe that there is a new_image or new_name setting within the upload library. But as I am fairly new to this framework I could be wrong.