$re = '/<[^>]*?href\s*=\s*"[^>]*?blogspot\.com[^>]*>(<img[^>]*?\/>)<\/[^>]*>/mi';
$str = '<a style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" href="http://3.bp.blogspot.com/xxxxxxx.JPG"><img src="xxxxxxxxxxxxxx" alt="" width="200" height="150" border="0" /></a>
';
$subst = "$1";
$result = preg_replace($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