You better off with DOMDocument
Class , Never use Regex
as a parser for parsing HTML Content.
$htmlsourceofthewebsite = file_get_contents('http://www.somewebsite.com');
$dom = new DOMDocument;
$dom->loadHTML($htmlsourceofthewebsite);
foreach ($dom->getElementsByTagName('img') as $tag) {
echo $tag->getAttribute('src');
}
}