Description:
------------
Don't know, if this is a bug in the "getimagesize()" function.


The "php_getimagetype()" compares just 3 bytes of the 4-byte array.
Source code: /ext/standard/image.c


PHPAPI int php_getimagetype(php_stream * stream, char *filetype TSRMLS_DC)
{
    ...
    PHPAPI const char php_sig_psd[4] = {'8', 'B', 'P', 'S'};
    ...
    } else if (!memcmp(filetype, php_sig_psd, 3)) {
    ...
}