$re = '/(?<=src=").*?\.(?:gif|jp[e]?g|png)/m';
$str = ' <p><img src="maquette_kuthawdaw.png" width="907"></p>
<p class="centered"><img src="photos/2019-11-28/large/20191128_095919_GM.bmp" width="49%">
<img src="photos/2019-11-28/large/20191128_100050_GM.jpg" width="49%"></p>
<p class="centered"><img src="photos/2019-11-28/large/2019112#_101710_GM.jpg" width="49%">
<img src="photos/2019-11-28/large/20191128_101541_GM.jpg" width="49%"></p>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php