$host = "http://google.com";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $host);
curl_setopt($ch, CURLOPT_POST, 0);
curl_setopt($ch, CURLOPT_COOKIE, 0);
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_NOBODY, 1);
curl_setopt($ch, CURLOPT_REFERER, $host);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_exec($ch);
curl_close($ch);

$fileUrl = "http://www.examplecom/test.jpg";
$AgetHeaders = @get_headers($fileUrl);
if (preg_match("|200|", $AgetHeaders[0])) {
// file exists
} else {
// file doesn't exists
}