标准的把图片转base64图片

$imageDetails = getimagesize($filename);
if ($fp = fopen($filename,"rb", 0)) {
   $picture = fread($fp,filesize($filename));
   fclose($fp);
   // base64 encode the binary data, then break it
   // into chunks according to RFC 2045 semantics
   $base64 = chunk_split(base64_encode($picture));
   $imageData = 'data:'.$imageDetails['mime'].';base64,' . $base64;
}