How to Retrieve Remote Image Headers in PHP Using get_headers, cURL, and apache_request_headers

PHP is a popular web programming language often used to develop dynamic sites and applications. In many web development scenarios, obtaining the HTTP header information of a remote image is required. This article presents three PHP methods for retrieving remote image headers, each with clear code examples and sample output.

Method 1: Using get_headers function

The get_headers function fetches the response headers of a given URL. Example code:

$url = "https://www.example.com/image.jpg";
$headers = get_headers($url, 1);
print_r($headers);

Sample output shows an associative array containing status line, date, server, content‑type, content‑length, and other header fields.

Method 2: Using cURL

cURL is a powerful PHP library for retrieving data from web servers, including header information. Example code:

$url = "https://www.example.com/image.jpg";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$headers = curl_exec($ch);
curl_close($ch);
print_r($headers);

The output displays raw HTTP header lines such as status, date, server, content‑type, and content‑length.

Method 3: Using apache_request_headers (via stream context)

This approach creates a HEAD request context and processes the returned headers. Example code:

$url = "https://www.example.com/image.jpg";
$context = stream_context_create(array('http' => array('method' => 'HEAD')));
$file_headers = get_headers($url, 1, $context);
$headers = array();
foreach ($file_headers as $key => $val) {
    if (strpos($key, 'HTTP') === 0) {
        $headers['Status'] = $val;
    } else {
        $headers[$key] = $val;
    }
}
print_r($headers);

The resulting array includes the HTTP status line and all other header fields, similar to the previous methods.

Summary

The article demonstrates several PHP techniques for quickly obtaining remote image header information, which can be useful for web development, caching strategies, and data analysis.