The GetImageSize() function will determine the size of any GIF, JPG, PNG, SWF, PSD or BMP image file and return the dimensions along with the file type and a height/width text string to be used inside a normal HTML IMG tag.
Returns an array with 4 elements. Index 0 contains the width of the image in pixels. Index 1 contains the height. Index 2 a flag indicating the type of the image. 1 = GIF, 2 = JPG, 3 = PNG, 4 = SWF, 5 = PSD, 6 = BMP. Index 3 is a text string with the correct "height=xxx width=xxx" string that can be used directly in an IMG tag.
With JPG images, two extras index are returned : channel and bits. channel will be 3 for RGB pictures, and 4 for CMYK pictures. bits is the number of bits for each color.
If accessing the filename image is impossible, or if it isn't a valid picture, getimagesize() will return NULL and generate a warning.
The optional imageinfo parameter allows you to extract some extended information from the image file. Currently this will return the different JPG APP markers in an associative Array. Some Programs use these APP markers to embedd text information in images. A very common one in to embed IPTC http://www.iptc.org/ information in the APP13 marker. You can use the iptcparse() function to parse the binary APP13 marker into something readable.
Note: This function does not require the GD image library.
Note: URL support was added in PHP 4.0.5