 <?php
header("Cache-Control: private, max-age=10800, pre-check=10800");
header("Pragma: private");
// Set to expire in 2 days
header("Expires: " . date(DATE_RFC822,strtotime(" 2 day")));
if(isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])){
  // if the browser has a cached version of this image, send 304
  header('Last-Modified: '.$_SERVER['HTTP_IF_MODIFIED_SINCE'],true,304);
  exit;
}


// Generate an image below either using GD or a file reader such as:
// readfile(), fread(), file_get_contents(), etc.

$path = "/path/to/my/image.jpg";
$info = pathinfo($path);
switch($info["extension"]){
    case "jpg":
        $mime = "image/jpeg";
        break;
    case "gif":
        $mime = "image/gif";
        break;
    case "png":
        $mime = "image/png";
        break;
}
header("content-type: $mime");
readfile($path);
?>