getimagesize()
Returns an array with 4 elements.
Index 0 contains the width of the image in pixels.
Index 1 contains the height in pixels.
Index 2 is a flag indicating the type of the image:
1 = GIF,
2 = JPG,
3 = PNG,
4 = SWF,
imagesetthickness()
Sets the thickness of the lines drawn when using imageellipse(), imagerectangle(), imagearc() and imagepolygon(). Format:imagesetthickness( $image_resource, $thickness_in_pixels);
The index of image functions on the official PHP web site is at http://www.php.net/manual/en/ref.image.php but it is so bloated (512K) that it can cause WebTVs to crash so I made my own list: