The following code snippet helps you to copy an image file from remote URL and save in a folder using PHP.
Make sure that you have write permission to the directory where you want to store the image; to make the folder writable you could do this:
$downloadImagePath='http://www.aboutcity.net/images/aboutcity.png';
$savePath = $_SERVER['DOCUMENT_ROOT'];
$ch = curl_init($downloadImagePath);
$fp = fopen($savePath . '/aboutcity.png', 'wb');
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_exec($ch);
curl_close($ch);
fclose($fp);
echo "Image Downloaded Successfully in ".$savePath.' Folder.';