exif_imagetype - Determine the type of an image
- filename - The image being checked.
exif_imagetype() reads the first bytes of an image and checks its signature.
PHP 4.3.0, 5
When a correct signature is found, the appropriate constant value will be returned otherwise the return value is FALSE. The return value is the same value that getimagesize() returns in index 2 but exif_imagetype() is much faster.