try it with fopen()
i used once this code:
$src = fopen($webcam,"r");
$dest = fopen("pic.jpg","w");
$cont = fread ($src, 9999999);
if ($cont) echo " read. ";
else echo " not read. ";
if ($cont != null)
{
if (fwrite($dest, $cont)) echo " written. ";
else echo " not written. ";
}
fclose($src);
fclose($dest);