It only uses newer routines for the completely different JPEG 2000 format. It uses the IJG code for its bog-standard JFIF JPEG file handling.

--
$,="\n";foreach(split('',"\3\3\3c>\0>c\177cc\0~c~``\0cc\177cc")) {$a++;$_=unpack('B8',$_);tr,01,\40#,;$b[$a%6].=$_};print@b,"\n"