How to check image format?

I read from a url e.g. http://www.ietf.org/images/logos/IETF_Logo_bmp_4-24-07.bmp

how do i use php to check the image format?

 

Check out this link-- http://www.mikekunz.com/image_file_header.html

Q..

 

function exif_imagetype will work

or you can do a strstr on the extension, but that wont check if it is actually an image just that the file extension is correct

 

thanks alot for the advice.. reps given..

 

you can also use getimagesize wich returns alot of common info (like image type, x, y)

http://www.php.net/getimagesize