exif_imagetype

Because I only want to check for jpeg or png from a memory string, this is my 2 functions that are quick and don't have any dependencies :<?php  function is_jpeg(&$pict)  {    return (bin2hex($pict[0]) == 'ff' && bin2hex($pict[1]) == 'd8');  }  function is_png(&$pict)  {    return (bin2hex($pict[0]) == '89' && $pict[1] == 'P' && $pict[2] == 'N' && $pict[3] == 'G');  }?>

By trial and error, it seems that a file has to be 12 bytes or larger in order to avoid a "Read error!".  Here's a work-around to avoid an error being thrown:// exif_imagetype throws "Read error!" if file is too smallif (filesize($uploadfile) > 11)    $mimetype = exif_imagetype($uploadfile);else    $mimetype = false;

Windows users: If you get the fatal error "Fatal error:  Call to undefined function exif_imagetype()", and you have enabled php_exif.dll, make sure you enable php_mbstring.dll. You must put mbstring before exif in the php.ini, i.e.:extension=php_mbstring.dllextension=php_exif.dllYou can check whether this has worked by calling phpinfo() and searching for exif.

If the function exif_imagetype() is not available,you can try the following workaround:if ( ! function_exists( 'exif_imagetype' ) ) {    function exif_imagetype ( $filename ) {        if ( ( list($width, $height, $type, $attr) = getimagesize( $filename ) ) !== false ) {            return $type;        }    return false;    }}