avatar eklıyordum ki

Fatal error: Call to undefined function imagecreatefromjpeg() in /home/king/public_html/forum/includes/usercp_avatar.php on line 323

boyle bir hata verdi

bu satır ise ;

$img_new = imagecreatetruecolor ($width, $height); 
         imagecopyresampled ($img_new, $img_old, 0, 0, 0, 0, $width, $height, $width_old, $height_old); 
         $image_function ($img_new, './' . $board_config['avatar_path'] . "/$new_filename"); 
         imagedestroy ($img_new);

çözemedim bi el atarmısnız?