<public:component>
<public:attach event="onpropertychange" onevent="propertyChanged()" />
<script>

var supported = /MSIE (5\.5)|[6789]/.test(navigator.userAgent) && navigator.platform == "Win32";
var realSrc;
var blankSrc = "images/blank.gif";

if (supported) fixImage();

function propertyChanged() {
if (!supported) return;

var pName = event.propertyName;
if (pName != "src") return;
// if not set to blank
if ( ! new RegExp(blankSrc).test(src))
fixImage();
};

function fixImage() {
// get src
var src = element.src;

// check for real change
if (src == realSrc) {
element.src = blankSrc;
return;
}

if ( ! new RegExp(blankSrc).test(src)) {
// backup old src
realSrc = src;
}

// test for png
if ( realSrc && /\.png$/.test( realSrc.toLowerCase() ) ) {
// set blank image
element.src = blankSrc;
// set filter
element.runtimeStyle.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + src + "',sizingMethod='scale')";
}
else {
// remove filter
element.runtimeStyle.filter = "";
}
}

</script>
</public:component>

  img {
    vertical-align:middle;
    border:0;
    behavior: url('png.htc');
  }