Big god PHP Generate picture problem urgent

Header ("Content-type:text/html;charset=utf-8");
Header ("Content-type:image/jpeg");
$image = Imagecreatefromjpeg ('./demo.jpg ');
$bgcolor = imagecolorallocate ($image, 0, 0, 0);
$fontcolor = Imagecolorallocate ($image, 255, 255, 255);
Header ("content-disposition:attachment;filename=demo.jpg");
Imagejpeg ($image);
Imagedestroy ($image);
?>
The above code download to the local after the picture prompt:
Windows Photo Viewer cannot open this picture because the file may be damaged, damaged, or too large.
Ask God for help

Reply to discussion (solution)

It's probably a BOM head.

I let the machine do the download, point to a little reaction is not ah, I was on the machine
Ask the great God, humbly.

