If accessing the filename image is impossible, or if it isn' t a valid picture, getimagesize() will return FALSE and generate a warning.
The optional imageinfo parameter allows you to extract some extended information from the image file. Currently this will return the diffrent 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.