And the images I'm referring to are the ones that can be embeddable in a web browser not .tif, .psd, etc.
So the only ones I'm aware of are .png / .jpg / .jpeg / .gif / .bmp
are there any more?
Reason why I need this info is to only allow valid images to be uploaded in my php file upload script.
you can do what ever you like, its all about the headers, and the information inside the actual image that determines the type. (mime-types)
hence why <img href='http://site.com/image.php?name=file'>
could actually render an image