The x-ray filter add the x-ray effect to the element.
#example {
filter: xray();
}
The original
<img src="image/friend.gif" alt="IMG" width="170" height="140">

<div style="font: bold 170% sans-serif; width: 100%;">
Example text
</div>
The x-ray effect
<img src="image/friend.gif" alt="IMG" width="170" height="140" style="filter: xray();">

<div style="font: bold 170% sans-serif; width: 100%; filter: xray();"> Example text </div>