正则去除图片width和height部分。该怎么解决

正则去除图片width和height部分。
有许多图片，有的有width和height，有的没有width和height。

如何使用正则去除所有图片的width和height部分？我的代码无效，求助。

PHP code

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<pre class="brush:php;toolbar:false"> 
<?php $s = '<img src="/static/imghw/default1.png"  data-src="http://www.blogcdn.com/www.engadget.com/media/2010/09/x-frame-2010-09-02-600.jpg"  class="lazy"  hspace="4" vspace="4" border="1" alt="Nagoya Institute folding X-Frame car lacks S-foils, hyperdrive, rolls on a big orange ball" /> 
<img src="/static/imghw/default1.png" data-src="http://media02.hongkiat.com/speed-performance-check/pingdom.jpg" class="lazy" alt="Pingdom" border="0" title="18 Website Speed and Performance Checking Tools">
<img src="/static/imghw/default1.png" data-src="http://blog.makezine.com/upload/2010/09/vice_grip_with_more_cowbell/expand-o.jpg" class="lazy"    style="max-width:90%" height="100px" alt="expand-o.jpg">';
$img=preg_replace('/ width="\d+" height="\d+"/', '', $s);
echo $img;
?> 

------解决方案--------------------

PHP code

 <div class="clear">
                 
              
              
        
            </div>