file_exists() returns false even if file exist (remote URL)

Question

My file_exists() returns false even if provided image to check https://www.google.pl/logos/2012/haring-12-hp.png exist. Why?

Below I am presenting full failing PHP code ready to fire on localhost:

$filename = 'https://www.google.pl/logos/2012/haring-12-hp.png';
echo "<img src=" . $filename . " />";
if (file_exists($filename)) {
    echo "The file $filename exists";
} else {
    echo "The file $filename does not exist";
}

Answer 1

$filename= 'https://www.google.pl/logos/2012/haring-12-hp.png';
$file_headers = @get_headers($filename);

if($file_headers[0] == 'HTTP/1.0 404 Not Found'){
      echo "The file $filename does not exist";
} else if ($file_headers[0] == 'HTTP/1.0 302 Found' && $file_headers[7] == 'HTTP/1.0 404 Not Found'){
    echo "The file $filename does not exist, and I got redirected to a custom 404 page..";
} else {
    echo "The file $filename exists";
}

Answer 2

A better if statement that not looks at http version

$file_headers = @get_headers($remote_filename);    
if (stripos($file_headers[0],"404 Not Found") >0  || (stripos($file_headers[0], "302 Found") > 0 && stripos($file_headers[7],"404 Not Found") > 0)) {
//throw my exception or do something
}