[jQuery] regular expression question

[Kush Murod]

Hi guys,
I have a regular expression question
Code below returns full image path if image is png:
------
var image = $$.css('backgroundImage');
if (image.match(/^url\(["'](.*\.png)["']\)$/i)) {
   image = RegExp.$1;
}
------
If I have filter for example:
var filter = 
"progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true,sizingMethod=crop,src='images/blah.gif')";
I would like to extract src value which is images/blah.gif
How do I do that
Thanks heaps
--Kush