div部分
<div class="cert_img"><p><img src="images/1.jpg" onload="fixImage(this,201,146)"/></p></div>
样式部分
.cert_img{ width:201px; height:146px; border:1px solid #bdbdbd;overflow:hidden; padding:6px;position:relative;display:table-cell;text-align:center;vertical-align:middle}
.cert_img p{ margin:0; padding:0;position:static;+position:absolute;top:50%}
.cert_img img{position:static;+position:relative;top:-50%;left:-50%;}
js部分，要先让js加载
<script type="text/javascript" language="javascript">
function fixImage(i,w,h){
var ow = i.width;
var oh = i.height;
var rw = w/ow;
var rh = h/oh;
var r = Math.min(rw,rh);
if (w ==0 && h == 0){
r = 1;
}else if (w == 0){
r = rh<1?rh:1;
}else if (h == 0){
r = rw<1?rw:1;
}
if (ow!=0 && oh!=0){
i.width = ow * r;
i.height = oh * r;
}else{
var __method = this, args = $A(arguments);
window.setTimeout(function() {
fixImage.apply(__method, args);
}, 200); ??? }
i.onload = function(){} }
</script>