$re = '~<img[^>]*?id=([\'"])(.+?)\1~';
$str = '<section>
<span><img id="id1" src="src" alt="alt"></span>
<span><img id="id2" src="src" alt="alt"></span>
</section>';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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