And so i am by using this wordpress function to obtain the customers image

the_author_meta('author_image', the_author_ID() 

and it'll either return something.jpg or something.png or something.gif whether it finds a picture otherwise it'll return an integer like 2330. Wouldso would i perform a preg_match or some conditional to tell me if the image exists. I believed to do a preg_match to ascertain if there's a period of time within the title but when someone includes a better idea that might be great..

Simpler:

if (is_numeric($author_image)){
  // this is presumably not a file
}

If all for you to do is look into the extension from the file to ascertain if it finishes with something (ex. '.jpg', '.png', etc.) you should use the answer presented here:

PHP startsWith() and endsWith() functions

I don't have knowledge of the library that you're using, but there should be an easy method to identify when the file is really a picture (some kind of meta data). Maybe reading through the documentation can help?

EDIT: I misinterpret the part concerning the function coming back integers if the image isn't found. The is_numeric() option would be most likely enough, but I'll leave my answer up to provide you with options (for instance, if you wish to separate image types).