PHP getimagesize alternative

Hi guys, There is an equivalent of getimagesize in autoit?

http://php.net/manual/en/function.getimagesize.php

I don't want to know the size of the image, but to know if a file is an image or not.

Like:

File.txt --> Renamed in File.jpg --> Check --> Not an image but TXT file

File2.html --> Renamed in File.png --> Check --> Not an image but html file

etc.

File3.jpg --> Check --> Is an image

Thanks to all